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Table of Contents

Protocols

Protocols

X.25

Presentation

The network processor manages the three interface levels (layers) between synchronous equipment and the public network. X.25 configuration is governed by the software license XPLS.

The levels/layers are defined in the ITU-T X.25 recommendations and in the OSI (Open System Interconnection) standard, issued by the ISO (International Standardization Organization).

These three levels/layers, managed by the FastPad equipment, are:


Table 6-1: Interface Levels (Layers)
Levels Layers according to the ISO standard X.25 ITU-T recommendations

1

Physical

Physical

2

Data-Link

Frame LAPB

2

Multi-Link

Multi-Link MLP

3

Network

Packet X.25

Physical level

This level transmits series of bits over the physical interconnection medium.

Frame level

This level is responsible for the error-free routing of data blocks over the physical line.

The operating principle of the frame level is in conformity with the LAP-B (Link Access Procedure-Balanced) modulo 8 and 128 procedure defined in the ITU-T. This procedure is equivalent to the "balanced" mode of the HDLC standard issued by the ISO, and like HDLC and supervisory, Information and Unnumbered Frame.

On this level, the network processor might be configured C12RxP1 in the following modes:

The frame level is established when the DTE-configured equipment sends an SABM frame and the DCE-configured equipment replies with a UA frame (SABM = Set Asynchronous Response Mode; UA = Unnumbered Acknowledge).

DTE mode:

The FastPad equipment takes the initiative to

DSE mode:

The local as well as the remote party of the FastPad equipment could take the initiative to connect or disconnect the frame level (as is the case in the DTE mode) by sending SABM or DISC.

DCE mode:

The FastPad equipment does not take the initiative to connect or disconnect the frame level. It issues a DM (= Disconnect mode) to indicate that it requests a mode setting command. The response could be:

SABM contention:

Whatever the type of connection (DTE, DCE or DSE), the FastPad equipment manages contention e.g. in case two SABM frames are sent, one by the DTE and one by the DCE equipment.

The Multi-link (MLP) level

The multi-link procedure is defined in ITU-T norm X.25-84. Its function is to distribute the packets among the available lines, each line operating according to the single line procedure, and restore the sequence of the packets on the remote side for further transfer to the packet layer.

To enable an MLP line to be managed, the line must be configured as belonging to an MLP bundle of the processor of the FastPad network. Configuration of the MLP bundle takes place in class 25, recurrences 0 to 8. MLP configuration is governed by the software license XPLS, XMLP.

The lines that may be configured in a bundle are of the dedicated or switched type (PSTN or ISDN). A switched line may be assigned dynamically in a bundle on the initiative of the Network Management System, a telemaintenance center or on the basis of certain load or overflow criteria.

In the case of the ISDN, a line may be shared by several bundles. In fact, the checking of the caller is possible on integrated ISDN, contrary to the case of the PSTN.

Certain foreign ISDN networks do not send the original calling number. In this case, the ISDN line cannot be shared.

The multi-link level is established after the following procedure has been executed:

For more details on MLP, refer to the section "Backup/Overflow/Dynamic Line Management (DLM)" in Chapter 7.

The Packet Level

This level assures the routing of the data packets across the network and flow control mechanism.

Logical Channel Organization (C12RxP4-15)

Signalling

The signalling of the FastPad equipment is based on X.25 standards issued in 1984. It changes with national implementation. C12RxP2 is used for doing the adaptation.

Facilities in X.25 Applications

Available facilities of the FastPad equipment are the following:

Facility markers

The response of the FastPad equipment to the facility markers mentioned in the X.25 standards can be configured (C12RxP83).

Permanent Virtual Circuit (PVC)

The FastPad equipment supports the PVC function, allowing data transmission between two subscribers at any time, without transmitting call request or clear packets (from a subscriber point of view). Data may be transmitted in full duplex.

Principle


Figure 6-1:
Diagram

On one FastPad node the PVC is configured as a calling PVC and on the other node as a called PVC.

A PVC is set up between a FastPad node and one or more subscribers.

At network level, the virtual circuits established are switched virtual circuits (SVCs).

A PVC may have two states:

These states are communicated to each device by means of reset packets.

Set-up of a PVC

Viewed from the FastPad equipment, set-up of a PVC is carried out in three phases:

  A call request packet is sent by the equipment that has the "calling" PVC configured. The PVC can not be used yet.
  The equipment that has the "called" PVC configured, responds with a call confirmation packet. The PVC on the called side changes state; it can be used now.
  The calling side receives the call confirmation packet. The PVC on the calling side can be used now; the data transmission is full duplex.

These three phases are illustrated below


Figure 6-2:
Diagram

FastPad X.25 Interfaces

The FastPad meets the requirements of the ITU-T X.25 recommendation. It offers three types of X.25 interfaces (see Figure 6-3, Figure 6-4 and Figure 6-5):

    1. an interface with an X.25 subscriber,

    2. an interface with a PSPDN public switch packet data network.

    3. an interface to another FastPad.

X.25 Interface of the FastPad


Figure 6-3: X.25 Interface of the FastPad

The behavior of the FastPad in case of a protocol error depends on the type of interface. The selection of the type of interface is made in the configuration.

X.25 Subscriber Interface

This interface is intended to connect X.25 subscribers to the FastPad. There are two profiles available:

Profile 1:

X.25 subscriber profile without additional services.

Profile 2:

X.25 subscriber profile with additional services.


Figure 6-4:
X.25 Subscriber Interface

Profile 1 offers the following services:

The call confirmation packet format and the reset sent by the FastPad are reduced (no address and no additional services).

Profile 2 has the following services available:

The call confirmation packet format and the reset sent by the FastPad are extended (additional services but no address service).

Public network interface

This interface gives the FastPad direct access to a public switched packet network or across a switched circuit network. Two profiles are available:

Profile 0:

Direct access connection to a public network with additional services; the throughput class and the packet window size are set to 2.

Profile 3:

Direct access connection to a public network without additional services; the packet window size set to 3.

Profiles to Connect to the PSPDN (PDN)


Figure 6-5: Connecting to the PDN

These types of interfaces with a PDN (Public Data Network) need special address processing.

The public network considers the FastPad as the CPE of a private PDN. At the subscriptions X.121 address is assigned to the CPE by the carrier.

A) Compacting/Decompacting (C12RxP52,1)

With the "Compacting/decompacting" tables in the FastPad, it is possible to translate a private network address (DNICZOAB) into a sub-address and vice versa.

To enable the FastPad to determine the position of the subscriber, the user must also supply the subscriber number on the public network.

So, when configuring the FastPad, the user must complete the compacting/decompacting tables (C11) and the PDN address table (C10).

The PDN address table gives information only about public networks where two addresses (called/calling) are used. The calling address then identifies the switch access point to the public network.

B) Address transport (C12RxP52,4)

The numeration over the public network can be done by using:

The private network "calling" and "called" addresses are transported across the public network in the complementary address extension service using the DTE marker (see the X.25 recommendations).


Figure 6-6: Public Network Lines

The lines with the public data network must be configured with parameter 52 = 4.

Node Zl puts the private addresses in the extension address facility field and adds the DTE marker. If the marker already exists, the addresses are inserted after the marker.

To be able to reach subscriber B, the private address of DTE B is translated into a public address using the called address inversion table for outgoing calls. This address corresponds with the public address of the node.

On the outgoing side of the public network, node Z2 re-forms the calling and called addresses, using the extension address facility. When only the facilities with the DTE marker are transmitted, the marker is suppressed.

For the operator, this procedure is transparent and compatible with the subscriber's use of the DTE marker and address extension facilities, at least when the maximum facility field size of a call packet is respected (See ITU-T X.25 recommendations).

FastPad Interface

This interface is intended to connect two FastPads to each other, directly or via a modem.

When the FastPads are connected via modems, an automatic backup via the PSTN can be made (see Figure 6-7).

The internal protocol assures the continuation of the communication in progress during the switch- over to the PSTN and back.

Backup takes place transparently for the users of the network.

The Network Management System is informed of the switch-over to the PSTN by the reception of an outstanding event, CT117 closed (CT117 = standby indicator).

Switching back is indicated by the opening of the CT117 contacts.


Figure 6-7: FastPad Interface

There are four profiles available:

Profile 4:

Inter node line, receiving clock signals (RC), circuits 114/115. The primary address = 0l and the logical channels are scanned in decreasing order.

Profile 5:

Inter node line, transmitting clock signals (TC), circuits 114/115. The primary address = 03 and the logical channels are scanned in increasing order.

Profile 20:

Inter node line with automatic backup via PSTN. The primary address = O1 and the logical channels are scanned in decreasing order.

Profile 21:

Inter node line with automatic backup via PSTN. The primary address = 03 and the logical channels are scanned in increasing order.

The X.25 protocol used between the FastPad requires that certain Parameters (primary address, scanning direction of logical channels) are in reverse on both ends of one FastPad link. Profiles 4 and 5, 20 and 21 manage these reversals.


Table 6-2: X.25 service parameters

Class 1 R1: type of line

<port #> : 1

X.25

Class 12 R <port#>

0 ?

X.25

Physical level parameters

P20,21,24,25


P26

P28

Signals requested to be present to declare the line in service.

Signals forced on the interface.

Access rate

Frame Level:

P1

P29

P32


P33


P34


P35

P36

P37

P38

Type of link

N1, frame size

T1, Time-out to receive an acknowledgment

T2, Time-out to acknowledge a frame

N2, retransmission counter

K, frame window

Modulo

Primary @

Secondary @


1 DTE, 2 DCE, 3 DSE

up to 8KB

(1-250)* 100ms


(1-127)* 100ms


(2-250)


(1-7) if modulo 8, (1-30) if modulo 128

8 for 8, 128 for 128

1 DTE, 3 DCE

1 DCE, 3 DTE

Packet Level:

P3


P4 - P15


P39

P40

P41

P42


P43



P44

P45


P46


P74

Logical Channel scanning direction

Logical Channel organization

T10, T20 restart timer

T12, T22 reset timer

T13, T23 clear timer

Nbr of retry for P39,40,41

Diagnostic code suppression for P39,40,41

Signaling type

Nbr of addresses in Call Request packet

Subscriber number, significant if P44 = 1

Call Conf packet format


0 decreasing, 1 increasing

(1-250)* 10s

(1-250)* 10s

(1-250)* 10s

(1-250)* 10s

1-250



(0 X.25 NT, 1 X.25 TE, 2 X.75

1 or 2

0 F+@, 1 F, 2 nothing

(1-250)* 10s

0 F+@, 1 F, 2 nothing

Facilities:

P48

CUG, Closed User Group

P49

RC, Reversed Charging

P54

FS,

Fast Select

P5

Throughput negotiation

P57

Def

Tx

P58

Def

Rx

P59

Max

Tx

P60

Max

Rx

P61

Packet negotiation

P62

Def

Tx

16B - 8KB

P63

Def

Rx

P64

Max

Tx

P65

Max

Rx

P66

Min

Tx

P67

Min

Rx

P68

W, window negotiation

1-7

P69

Def

Tx

P70

Def

Rx

P71

Def

Tx

P72

Def

Rx

P90

Nbr of PVC

Up to 250 per equipment

P91

Entry index for the First PVC
in C17R0

Specific:

P2

P52

P53

P81

P82

P83

P89

Type of connection

PDN link

entry index in C10r0

Call return (trunk)

Call return(subscriber)

facility marker control

@ conversion/aimed point

08 Telenet, 12 Tymnet, 52 Uninet, 64 Itapac

0 no, 1 yes, 4, yes & @ transport

to define the X.121 PDN @. Only if 45 = 2


Table 6-3: LAP-B Frame Overview

CATEGORY

COMMANDS

RESPONSES

CONTROL FIELD

HEX VALUE

I-FRAME

I

7

r

r

r

r

0

0

0

1

1

6

r

r

r

r

0

1

1

0

0

5

r

r

r

r

1

0

1

0

0

4

P/F

P/F

P/F

P/F

P

P

P

1

P

3

s

0

0

1

1

1

1

1

1

2

s

0

1

0

1

1

0

0

1

1

s

0

0

0

1

1

1

1

1

0

0

1

1

1

1

1

1

1

1

P/F = 1

even

x1 1

x1 5

x1 9

1F

1F

1F

1F

1F

P/F = 0

even

x2 1

x25

x2 9

1F

1F

1F

1F

1F

S-FRAME

RR

RNR

REJ

RR

RNR

REJ

U-FRAME

SABM

DISC

DM

UA

FRMR

r = receive counter 1 odd number

s = send counter 2 even number

P = poll bit

F = final bit

General X.25 Packet Overview


Table 6-4: X.25 Packet

7

6

5

4

3

2

1

0

BIT

BYTE

1

GENERAL FORMAT ID

LOGICAL CH. GROUP NO.

Q

D

N

N

2

LOGICAL CHANNEL NUMBER

3

PACKET TYPE IDENTIFIER

4

OTHER FIELDS

n


Table 6-5: X.25 Packet

FROM DTE TO DCE

FROM DCE TO DTE

PACKET TYPE ID. (hexadecimal)

Call set-up and clearing

Call Request

Call accepted

Clear request

DTE Clear confirmation

Incoming call

Call connected

Clear indication

DCE Clear confirmation

/0B

/0F

/13

/17

Data and interrupt

DTE data

DTE interrupt

DTE interrupt confirmation

DCE data

DCE interrupt

DCE interrupt confirmation

/even

/23

/27

Flow control and reset

DTE RR (mod 8)

DTE RR (mod 128)

DTE RNR (mod 8)

DTE RNR (mod 128)

DTE REJ (mod 8)

DTE REJ (mod 128)

Reset request

DTE reset confirmation

DCE RR (mod 8)

DCE RR (mod 128)

DCE RNR (mod 8)

DCE RNR (mod 128)

Reset indication

DCE reset confirmation

/x1

/01

/x5

/05

/x9

/09

/1B

/1F

Restart

Restart request

DTE restart confirmation

Restart indication

DCE restart confirmation

/FB

/FF

Diagnostic

Diagnostic

/F1

Registration

Registration request

Registration confirmation

/F3

/F7

Examples

X.25 SVC Configuration


Figure 6-8:
X.25 SVC Configuration


Table 6-6:

C1R1 ( type of the link)

C1R1

1 1

<trunk #> 1

1 1

<trunk #> 1

C1R1 ( type of the link)

C1R1

0 900000

0 800000

C12R1 (service parameters)

C12R1

0 1 ( X.25 DCE user profile)

1 2,0 (X.25 network)

2 5,11 (1st incoming Lcn)

3 9,1 (1st both ways Lcn)

4 11,10 (Nbr of bothways)

5 13,1 (1st outgoing Lcn)

6 28,10 (access rate 9600b/s)

7 32,30 (T1 = 3s)

8 33,10 (T2 = 1s)

9 35,7 (k = 7)

10 45,2 (mode 2 addresses)

11 48,0 (no CUG)

12 56,0 (no throughput neg)

13 74,0 (short call conf format)

default value

29,2 (frame size = 256B)

62,7 (Tx-packet size = 128)

63,7 (Rx-packet size = 128)

69,2 (Tx-window size = 2)

70,2 ( Rx-window size = 2)

0 1 ( X.25 DCE user profile)

1 2,0

2 5,3

3 9,1

4 11,2

5 13,1

6 28,10

7 32,30

8 33,10

9 35,7

10 45,2

11 48,0

12 56,0

13 74,0

default value

29,2 (frame size = 256B)

62,7 (Tx-packet size = 128)

63,7 (Rx-packet size = 128)

69,2 (Tx-window size = 2)

70,2 ( Rx-window size = 2

C12R <trunk #>

C12R <trunk #>

0 5 X.25 DCE trunk profile

default value

11,20 (Nbr of bothways)

29,2

62,7

63,7

69,3

70,3

0 4 X.25 DTE trunk profile

default value

11,20 (Nbr of bothways)

29,2

62,7

63,7

69,3

70,3

X.25 Configuration

X.25 PVC Configuration


Figure 6-9: X.25 PVC Configuration


Table 6-7: X.25 PVC Configuration

C1R1 ( type of the link)

C1R1

1 1

<trunk #> 1

1 1

<trunk #>

C1R2

C1R2

0 900000

0 800000

C12R1 (service parameters)

C12R1

0 1 ( X.25 DCE user profile)

1 2,0 (X.25 network)

2 5,13 (1st incoming Lcn)

3 9,3 (1st bothways Lcn)

4 11,10 (Nbr of bothways)

5 13,3 (1st outgoing Lcn)

6 28,10 (access rate 9600b/s)

7 32,30 (T1 = 3s)

8 33,10 (T2 = 1s)

9 35,7 (k = 7)

10 45,2 (mode 2 addresses)

11 48,0 (no CUG)

12 56,0 (no throughput neg)

13 74,0 (short call conf format)

14 90,2 (Nbr of PVC)

15 91,1 (1st entry in C17R0)

0 1 ( X.25 DCE user profile)

1 2,0

2 5,4

3 9,2

4 11,2

5 13,2

6 28,10

7 32,30

8 33,10

9 35,7

10 45,2

11 48,0

12 56,0

13 74,0

14 90,1

15 91,1

C12R<trunk #>

C12R<trunk #>

0 5 X.25 DCE trunk profile

0 4 X.25 DTE trunk profile

C17R0

C17R0

0 0,1,1,1

0 not significant

1 called side

1 local Lcn number

1 remote Lcn number

1 0,1,2,2

0 not significant

1 called side

2 local Lcn number

2 remote Lcn number

0 1,0,1,1

1 1st entry in C8

0 calling side

1 local Lcn number

1 remote Lcn number

C8R0

C8R0

0 90001001 Called address

C8R4

C8R4

0 1

X.25 PSPDN configuration

X.121 address of the FastPad is 196810. The PSPDN works in two addresses.


Figure 6-10:
X.25 PSPDN Configuration


Table 6-8: X.25 PSPDN Configuration

C1R1 ( type of the link)

1 1

<trunk #> 1

C1R2 C2R2

0 800030

6 0 (insertion of the compacted Sub @)

C12R1 (service parameters) C12R<trunk #>

0 1 ( X.25 DCE user profile)

1 2,0 (X.25 network)

2 5,1 (1st incoming Lcn)

3 9,1 (1st bothways Lcn)

4 11,4 (Nbr of bothways)

5 13,5 (1st outgoing Lcn)

6 28,10 (access rate 9600b/s)

7 32,30 (T1 = 3s)

8 33,10 (T2 = 1s)

9 35,7 (k = 7)

10 45,2 (mode 2 addresses)

11 48,0 (no CUG)

12 49,0 ( no Reverse Charging)

13 54,0 ( no Fast Select)

14 56,0 (no throughput neg)

15 74,0 (short call conf format)

16 85,2 (short clear request format)

default value

29,2 (frame size = 256B)

62,7 (Tx-packet size = 128)

63,7 (Rx-packet size = 128)

69,2 (Tx-window size = 2)

70,2 ( Rx-window size = 2)

0 1 ( X.25 DCE user profile)

1 2,0

2 5,3

3 9,1

4 11,2

5 13,1

6 28,10

7 32,30

8 33,10

9 35,7

10 45,2

11 48,0

12 56,0

13 74,0

default value

29,2 (frame size = 256B)

62,7 (Tx-packet size = 128)

63,7 (Rx-packet size = 128)

69,2 (Tx-window size = 2)

70,2 ( Rx-window size = 2

C10R0

0 196810 (PSPDN @ for the FastPad)

C11R0

C11R1

0 2 (length of the compacted Sub@)

0 3001,01 (compacting/decompacting)

1 3002,02

2 3003,03

Leased line backed-up by modem itself

In this case, profiles allow a failure of the leased line, which is transparent to users. This is possible because of the high values used for N2 and T1 at the Data Link Level.

These profiles are quite similar to profiles 4 and 5. However they must be used to indicate whether the modem uses the leased line or the PSTN network (outstanding events).

Figure 6-11 illustrates this case.


Figure 6-11: Example

When the leased line (LL) fails, the modem automatically dials a stored PSTN number. When the leased line is restored, the modem hangs up the PSTN line.

During the backup/restore interval time, the virtual circuits are not cleared. The default values for parameters 22, 23 and 34 in profiles 20 and 21 configured on the mp's, are set according to the maximum backup/restore delay.

Table 6-9 shows the corresponding configuration.


Table 6-9: Configuration

900010

900020

CLASS 1 RECURRENCE 1

0 1 X.25

0 1 X.25

CLASS 12 RECURRENCE 0

0 20 X.25 DTE PSTN automatic backup by modem

Default values

22,10 signal monitoring interval

23,128 number of signal monitoring interval

34,128 frame retransmissions (N2)

0 21 X.25 DCE PSTN automatic backup by modem

Default values

22,10 signal monitoring interval

23,128 number of signal monitoring interval

34,128 frame retransmissions (N2)

Configuration of an X.25 line

The following diagram describes the steps of the configuration process of an X.25 line, using profiles.

Additional parameters can be configured according to each user's specific needs.

Often modified parameters include the following:

The X.25 line parameters that can be modified are described in Chapter 4.


Figure 6-12:
Configuration of an X.25 Line
Figure 6-13:
Configuration of an X.25 Line (Con't.)
Figure 6-14:
Configuration of an X.25 Line (Con't.)

HDLC-T

The HDLC-T is governed by the software license (TRAN).

Overview

The FastPad allows any HDLC-compatible device using any protocol with error recovery, usually one delimited by flags, e.g. HDLC, SDLC, LAPB, PPP synch.,...to use HDLC-T features.

Principle

HDLC-T is a point-to-point connection. When the line is in service, the subscriber port uses the automatic calling behavior (C8R0, R4) to establish a logical link (C17R0) between two subscribers.


Figure 6-15: Example

Class 17 Rec 0

For each entry, there are four fields (A, B, C, D):

A: entry index in C8R0, R4
B: Type of call 0 calling
1 called
2 mixed
C: Always set to 0
D: Subscriber No.

Figure 6-16: Example



Table 6-10: Configuration

C1

R1

C1

R1

1

20

2

20

C12

R1

C12

R2

0

1

2

82

28, 15

91, 1 (find entry in C17R0)

0

1

2

82

28, 15 64tcb/s

91, 1

C17

Rec 0

C17

Rec 0

0

1, 0, 0, 68

0

1, 1, 1, 71

C9

Rec 4

C9

Rec 4

36

68

36

71

C9

Rec 5

C9

Rec 5

36

1, 1, 0, 1

36

1, 1, 0, 2

C4

Rec 7

C4

Rec 7

0

1, 1, 0, 0

0

1, 1, 0, 0

C8

R0

C8

R0

0

80000071

0

80000068

C8

R1

C8

R1

0

01, 80

0

01, 80

C8

R4

C8

R4

0

1

0

1

C8

R5

C8

R5

0

CD*

0

CD*

* refer to Chapter 4 "Encapsulation Type".

As soon as line 1 of 9000 00 is in service, port 1 will generate a call to reach 8000 00 71.

Work sheet

Project name:

Customer @:

Contact points:

Date:

Objective:

Diagram:

Node address:

Port number:


Figure 6-17:
Example
Table 6-11:

Class 1 R1: type of line

Class 1 R1: type of line

<port #> : 20

HDLC-T port # :

<port #> : 20

HDLC-T port # :

Class 12 R <port#>:

Connection parameters

Class 12 R <port#>:

Connection parameters

0

82: HDLC profile

0

82: HDLC profile

P28

speed

P28

speed

P32

P33

P91

CRC check ( ) 0 = yes, ( ) 1 = no

Nbr. of flag: 1 up to 15

Entry R in C17R0

P32

P33

P91

CRC check ( ) 0 = yes, ( ) 1 = no

Nbr. of flag: 1 up to 15

Entry R in C17R0

Class 17 R0

Class 17 R0

<R-1>

A, B, C, D: 1,0,

A: Entry Q in C8R0, R1, R4, R5

B: 0 1 calling, 1 called
2 both-way

C: always 0

D : subscriber @, y:

<R-1>

A, B, C, D: 1,0,

A: Entry Q in C8R0, R1, R4, R5

B: 0 1 calling, 1 called
2 both-way

C: always 0

D : subscriber @, z:

C9 R4

C9 R5

C9 R4

C9 R5

? y

? 1,1,0,<port #>

? Z

? 1,1,0,<port #>

C8 R0

Remote @

C8 R0

Remote @

<Q-1>

CDZ

<Q-1>

ABy:

C8 R1

C9 R4

C8 R1

<Q-1>

01, 80

<Q-1>

01, 80

C8 R4

Slow call time

C8 R4

Slow call time

<Q-1>

( ) 0, No ( ) 1-99/*10s

<Q-1>

( ) 0, No ( ) 1-99/*10s

C8 R5

Encapsulation type

C8 R5

Encapsulation type

<Q-1>

( ) CD ( ) FD

<Q-1>

( ) CD ( ) FD

Configuration

Frame Relay

General description

Frame relay (FR) is a frame mode transfer service for long distance communication (WAN: Wide Area Network). This service is based on the modified LAP-D structure (LAP-D: Link Access Procedure on D-channel). The term LAP-F stands for: LAP-for Frame mode support services. LAP-F data is multiplexed on (OSI) level 2.

Signalling relative to this service is managed by the LMI function (Local Management Interface = ITU-T Q.933 and ANSI T1.617 (See Chapters 10 and 13 of this manual).

LAP-F = ISO standard Q.922.

Description of Relayed Frames

There are two types of frames:

Information Frame


Figure 6-18: Information Frame Structure

Legend

DLCI

=

Data Link Connection Identifier

DE

=

Discard Eligibility bit

BECN

=

Backward Explicit Congestion Notification bit

FECN

=

Forward Explicit Congestion Notification bit

C/R

=

Command/Response indication bit

msb

=

Most Significant Byte

lsb

=

Least Significant Byte

CRC

=

Cyclic Redundancy Check

Signalling Frame


Figure 6-19: Signalling Frame Structure (LMI)

Local Management Interface

A local management interface of the frame service is offered. It enables a subscriber to determine the status of the PLLs (Permanent Logical Links) of the network and prohibits him from using a PLL which is not available. It supplies the procedures making it possible to detect and modify the following events:

For this purpose, the LMI of the subscriber (subscriber LMI) regularly transmits status enquiry messages. The LMI of the network (network LMI) replies with status report messages.

Two standard protocols are used for the local management interface:


Figure 6-20:
FastPad Configuration as Subscriber LMI (UNI) or Network LMI (NUI)

The FastPad can be configured as a subscriber LMI (UNI) (when it is facing a Frame Relay network), or a network LMI (NUI) (when it is facing an FR subscriber).

Definitions

PLL = Permanent Logical Link

Sub-layer FR2.0 is the relay service. It manages only the bits representing the DLCI number in the heading.

Sub-layer FR2.1 is the frame switching and network congestion service. It manages the FECN, BECN, DE and C/R bits. RT2.0 and RT2.1 represent the core of Q.922.

Sub-layer FR2.2 represents the entire protocol as defined in Q.922. This protocol is generally active in the network periphery in the subscriber terminals.

Types of Interfaces

The FastPad equipment offers several types of interfaces:

A) Subscriber Interface

B) Network Interfaces (FRTE)

Note As the FRIP function encapsulates only IP datagrams and is always called, the user call data must have the value CC or DC or FC depending on the desired encapsulation.
Note 
1) "Transparent HDLC" and "FRA" (FR2.1) protocols can be brought on-line when equipment supporting this protocol is also present on the other end of the line to guarantee end-to-end management.
2) Sub-layer FR2.0 protocol is a support service in frame relay that contributes to the establishment of a PLL between the local and the remote terminal. This protocol is put into service in FRSW. It does not allow the multiplexing of "subscriber" PLLs on the "network" PLL; this facility is offered by putting the FRA into service on the subscriber side and FRI on the network side (FR I).
3) X.25 level 2 related to the FR2.0 sub-layer are functionally identical to level FR2.2 and the related FR2.0 sub-layer. Frame relay, encapsulated in X.25 protocols, allows multiplexing of subscriber PLLs on a PLL network, but in that case the symmetrical equipment must be able to manage the same function on the remote side.

Figure 6-21: Example: Frame Relay Network

Constraints and limitations

Configuration of Frame-Relay Lines, Type "Switch" (FRSW) End Connection Voice Device

The following diagram gives the steps in the configuration process of a frame relay switch interface for an incoming and an outgoing line using the standard profile.

Additional parameters can be configured according to specific needs of the user.

Details of the parameters are described in Chapter 4.

Caution:

The two lines to be configured must be on the same module.

Reminder.


Figure 6-22: Speed versus Max. Packet Size


Figure 6-23:
Configuration of Frame Relay Lines

Configuration of an HDLC or Frame Relay Subscriber (FRA) Line

The following diagram gives the steps in the configuration process of an HDLC or frame relay subscriber Interface using the standard profiles.

Additional parameters can be configured according to specific needs of the user.

Details of the parameters are described in Chapter 4.


Figure 6-24: Configuration of a Frame Relay Subscriber (FRA) Line (Con't)
Figure 6-25: Configuration of a Frame Relay Subscriber (FRA) Line (Con't)

Configuration of PLLs multiplexed on an FRTE interface, concerns the FRI, FRSNA, FRIP and FRT protocols

As these PLLs have no implicit physical output port, at least one frame relay line in class 1, recurrence 1 must be configured 18 (frame relay) enabling the routing tables to be configured in class 32.

The frame relay physical lines have an 84 profile (DTE) or 85 profile (DCE) defined in class 12. For these two profiles, only the parameters related to the physical line level are significant and possibly an 84 profile in class 13 which defines the LMI parameters (LMI is optional). LMI is not offered for transit couples (FRSW).

In class 30, the connection parameters of levels 2 and 3 of each PLL are defined by means of profiles (see available profiles).

Class 32 represents the routing tables of all PLLs of the switch. There are two recurrences: one for incoming and one for outgoing lines. In each recurrence, the line number, the DLCI type and the DLCI number must be configured.

Recurrence 0 describes the physical lines with the different DLCI numbers and their types.

Recurrence 1 describes the physical lines of the PLL: the PLL number and the recurrence of the profile defined in class 30 of the PLL are indicated.

  Lines 1 and 2 of any protocol are multiplexed on line 3 FR. The two protocols are encapsulated in X.25 and in FR2.0 by means of the Network FR function (virtual lines must be chosen between 160 and 239 and between 65 and 124).
  On line 4, the two protocols P1 and P2 are received with two different DLCI numbers. For protocol Pl, the DLCI number is declared as "connection", enabling the frame relay to return the frames in the upper layers (Network FR).
  For protocol P2 the DLCI has been configured transit, enabling a fast passage of the frames through ZO1 for transmission on line 6.

REMARK: For simplification, it is recommended that the virtual line number and the DLCI number of the PLL should be made equal on the physical line.

This rule is applicable, for adjacent nodes in which, as in this example, line 160 should have an odd profile number. This departs from the FastPad rule.


Figure 6-26: Configuration of an Internal Frame Relay (FRI) Line (Con't).
Figure 6-27: Configuration of a Frame Relay Network with Transit and PLLs.
Figure 6-28: Configuration of Z01
Figure 6-29: Configuration of Z02
Figure 6-30: Configuration of Z03
Figure 13-12: Example of FNA/FRA Configuration

C1R1

P4 = 21

line 4 = FRA

C12R4 \xde line 4

P0 = 83

FRA profile

P1 = 90,2

2 DLCIs (101 and 88)

P2 = 91,10

rest of description in C17R0 row 10

P3 = 92,2

LMI of NUI (Network to user) type and still of network type

C17R0


Figure 13-13:
C17R0

This local (AB SA) is used to format the address of the called number in the call packet as follows:


Figure 6-31: Example of FNA/FRA Configuration (Continued)

REMARK: It is possible to choose to configure only a local (AS) in C17 with all the restrictions that this implies. The calling address in the call-request packet then has the following form:


Figure 6-32: Example of FNA/FRA Configuration (Continued)
Figure 6-33: Example of FNA/FRA Configuration (Continued)
Figure 6-34:
FRSNA Example

Practical Viewpoint on Frame Relay

First Example:

Figure 6-35: Frame Relay subscriber using FRI for encapsulation
Figure 6-36: Encapsulation proposed on FR line: number of overhead bytes in parentheses.

The SEP field of the multiframe protocol is negotiated between FRA. It is thus optional.

Second example:

Figure 6-37: Any subscriber using FRI for encapsulation
Figure 6-38: Encapsulation proposed on FR line:

REMARKS

    1. In these two examples, the X.25 VC encapsulated in FR is established end to end between two network elements via the FRA protocol.

    2. In the following cases, the internal VC is established locally on each machine between the subscriber protocol (FRA, "P", SDLC, S.25, IP) and the protocol offered on the network interface (FRSNA, FRIP, FRT).

Third example:

Figure 6-39: Frame relay subscriber using FRT.
Figure 6-40: Encapsulation proposed on FR line:
Fourth example

Figure 6-41: Any subscriber using FRT
Figure 6-42: Encapsulation proposed on FR line:
Fifth example:

Figure 6-43: SDLC Subscriber using FRSNA
Figure 6-44: Encapsulation proposed on FR line:
Sixth example:

Figure 6-45: X.25 Subscriber using FRSNA (mpSI)
Figure 6-46: Encapsulation proposed on FR line:
Seventh Example

Figure 6-47: LAN subscriber using FRIP:
Figure 6-48: Encapsulation proposed on FR line:

REMARKS

    1. The FRI, FRSNA, FRIP and FRT stacks are represented by logic lines. As there may be several types of multiplexed stacks on a physical line, routing must be via the PLL ([65, 128] and [160, 239]) initialized in Class 32 Recurrence 1.

    2. ZO (DNIC ZO AB) to PLL of normal/backup line output. The supporting VC (internal or external) is established by means of the routing tables (C9...). The end of the PLL allows the remote node to be identified by means of the associated ZO number. It is thus recommended that calls be routed by configuring the ZO of the remote equipment.


Figure 6-49: Example

Example of routing table for PLL linking switch ZO = 00 with ZO = 01.

Routing table of switch 00:

Routing table of switch 01:

When several PLLs use different protocols, it is recommended that these internal VCs be routed by using different ZOs (one ZO per PLL) or routing at the level of the AB.

FR

Two RFCs define the extension of MIB II to describe the Frame-Relay interface. RFC 1604 for DCE and RFC 1315 for DTE. Only global physical interface management is proposed and limited to the description in the MIB II of the interface group. Transmission groups is for subsequent study. One * means not used, ** means not available.


Table 6-14: FR Group Objects
Object Name Meaning Access

ifIndex

Interface number

Read only

ifDescr

Interface description

Read only

ifType

Interface type

Read only

ifMtu

Maximum octets in datagram

Read only

ifSpeed

Bandwidth in bits per second

Read only

ifPhysAddress

Lowest layer physical address

Read only

ifAdminStatus

Interface status desired

Read-write

ifOperStatus

Interface status current

Read only

ifLastChange

Value of sysUpTime on interface

Read only

ifInOctets

Total octets received on interface

Read only

ifInUcastPkts

Number of packets to n + 1 layer

Read only

ifInNUcastPkts

Non-unicast packets to n + 1 layer

Read only

ifInDiscards

Inbound discarded packets/flow control

Read only

ifInErrors

Inbound packets discarded due error

Read only

ifInUnknownProtos

Inbound packets with protocol error

Read only

ifOutOctets

Total octets transmitted on interface

Read only

ifOutUcastPkts

Transmit requests from layer n + 1

Read only

ifOutNUcastPkts

Number non-unicast transmit requests

Read only

ifOutDiscards

Outbound packets discarded/flow control

Read only

ifOutErrors

Outbound packets discarded due error

Read only

ifOutQlen *

Packet size of output queue

Read only

ifSpecific

MIB-specific pointer

Read only

IfName **

not used

IfInMulticastPkts **

nbr of multicast frames received error free

Read only

IfInBroadcastPkts **

not used

IfOutMulticastPkts **

nbr of multicast frames transmitted error free

Read only

IfOutBroadcastPkts **

not used

IfHCInBytes **

nbr of bytes received useful for .DS3 interface

Read only

IfHCOutBytes **

nbr of bytes transmitted useful .DS3 interface

Read only

IfLinkUpDownTrapEnble **

trap transmission authorization

Read only

IfHighSpeed

rate in Mbps, if lower that 1Mbps then set to 0

Read only

IfPromiscuousMode

set to False

IfConnectorPresent

set to False

Configuration structure

Class 24 Rec X(6-8) 6 for M0, 7 for M1, 8 for M2

Class 9 Rec 4 Subscriber number for VR

0

1

2

3

4

5

6

7

8

9

10

11

12

112

90,x

91,o

23,1

26,x

27,o

28,x

29,p

30,q

31,r

32,1

33,s

46,z

profile for virtual router

number of LLC up to 200 (0-200)

1st entry in C17 Rec 0 up to 200 (0-200)

intermediate routing

routing option: 0 static route; 1 static route & default one.

static route type

number of remote Ip @ range C31 Rec 14

1st entry in C31 Rec 14

entry in C31 Rec 15 for the default route (0-3)

entry index in C31 Rec 7 for the Wan Ip @

always set to 1.(number of local range of Ip@)

entry index in C31 Rec 8, 11 for the LAN Ip @ and its behavior.

subscriber number.(default one is 95).

Class 9 Rec 5 SAP (virtual line) for VR

x

1,1,0,y

y=

60 if on M0

61 if on M1

62 if on M2

Class 31 Rec 7 Recurrence for the Wan Ip address (Host Id)

Class 31 Rec 19 for Community string

r

0 for read-only

1 for read/write

2 for trap messages

Class 31 Rec 8 Recurrence for the LAN Ip address.

s

Class 31 Rec 11 Recurrence for the behavior of the LAN Ip @

s

t,0,0,0,0,0

t:

entry index in C31 Rec 12,13 for the Local range of Ip @

Class 31 Rec 12 Recurrence where is define the LOWEST Ip @ of the range.

Class 31 Rec 20 for Client @(up to 6)

X A, B, C, D, z

A, B, C, D is the IP @

z: entry index(0-2) in C31 Rec 19

Class 31 Rec 13 Recurrence where is define the HIGHEST Ip @ of the range.

Class 31 Rec 14 Mapping between the range of Ip @ and the LLC Id.

Class 31 Rec 21 for Trap DA (up to 3)

p

A,B,0

A:entry index in C31 Rec (12, 13)

B: LLC Id(1-199)

0: field not used, always 0.

Class 31 Rec 15 up to three entries

Class 8 Rec 0 Remote X.121 @

q

B

B: for the LLC Id of the default route

Class 8 Rec 1 Fast select

Class 17 Rec 0 Mapping between the LLC Id and the remote X.121 @.

x 01, 80 optional

o

A, B, C, 0

A: first entry in C8

B: LLC type; 0 calling, 1 called, 2 mixed, 3 datagramme

C: LLC Id

0: field not used always 0.

Class 8 Rec 4 Slow call timer

x 0 inactive

1 steps of 10s

Class 8 Rec 5 Encapsulation type

x CC, 08, 00 for IP and RFC 1356 or Virtual Router.

CC, 03, CC for IP and FRA

ISDN

Components

ISDN components include Terminals, Terminal Adapters, Network Termination devices, Line Termination equipment, and Exchange Termination equipment (see Figure 6-49).

Beyond the TE1 and TE2 devices, the connection point in the ISDN network are the Network Termination devices.

Beyond the NT1 and NT2, the next connection points are:

Reference Points

A number of reference points are specified in ISDN. These reference points define logical interface between functional groupings (See Figure 6-50)


Figure 6-50: Communication Equipment in connectionless Mode

The ISDN exchange terminators are interconnected via communication devices using Common Channel Signaling System Nº 7 (CCSS#7). This is a connectionless mode.

Access

Two main interface structures have been defined, the Basic interface and the Primary.


Table 6-15: ISDN
Access BRI PRI
Channel

2B + D

30 B + D

Data rate

2*64 + 16 = 144 kbps

30*64 + 64 = 1984 kps

Real rate

144 + 48 = 198 kbps

1984 + 64 = 2048 kbps

Access

The difference between real rate and data rate is due to the fact that in addition to these channels ISDN provides for framing control and other overhead bits.

Connector

The interface connector used for the TEs and NTs is an 8 pin so-called RJ connector.

This connector is specified in the ISO 8877 standard. The RJ connector for ISDN is denoted as RJ-45 connector. The layout of this connector is shown in Figure 6-51. The maximum number of wires in the interface is 8, but mostly only 4 wires are used.


Figure 6-51: ISDN
Connector
Table 6-16: Connector Pinout
Pin Signal

1

not used

2

not used

3

TD

4

TD

5

RD

6

RD

7

not used

8

not used

Via the balanced transmit and received lines, power is distributed from NT towards the TEs.This power distribution takes place via a so-called phantom circuit.

This power source has a nominal voltage of 40 volts and should supply a power of at least 420 milliwatts.


Figure 6-52: ISDN Recommendations for Protocols in Different Layers

Figure 6-52 illustrates the ISDN recommendations for the protocols in the different layers. Levels 2 and 3 are significant for D-channel.

Physical layer

For the physical layer, two protocols are possible:

These protocols describe how to transfer the information across the medium.The protocol of the physical layer is based on Time Division Multiplexing (TDM).

Basic rate interface structure

The bits are grouped together into frames of 48 bits each.

The nominal bit rate is 192 kbps. Every 250 µs one frame is transmitted. This results in a transmission of 4000 frames per second.

ISDN physical-layer frame format differs depending on whether the frame is outbound (from terminal to network) or is inbound (from network to terminal).

Primary rate interface structure

The Primary rate interface (E1) has a frame structure that consist of 32 time slots of 8 bits each.

The number of bits in a frame is 256. Every 125 µs one frame is transmitted. This results in a transmission rate of 8000 frames per second are transmitted, which results in a nominal bit rate of 2048 kbps.

DATA Link Layer

Layer 2 of the ISDN signaling protocol is Link Access Procedure, D-channel, also known as LAP-D. LAP-D is similar to High-level Data Link Control (HDLC) and Access Procedure Balanced (LAP-B).

As LAP-D's extended acronym indicates, it is used across the D-channel to ensure that control and signaling information flows and is received properly. LAP-D's frame format  (see Figure 6-53) is very similar to that of HDLC and like HDLC, LAP-D uses Supervisory, Information and Unnumbered frames. The contention mechanism used on D-channel is the Carrier Sense Multiple Access - Collision Resolution (CSMA/CR).

The LAP-D protocol is formally specified in ITU-T I.441 (= Q921).


Figure 6-53: Data Link Layer

DLCI: Data Link Control Identifier

SAPI: Service Access Point Identifier

E/A: Address Field Expansion Bit D

C/R: Command/Response Bit

TEI: Terminal End Point Identifier

DSS1 : Digital Signaling System one (D protocol).


Figure 6-54: LAP-D
Address Field

The LAP-D address field is two bytes long. The address field identifies the intended receiver of the command frame or the transmitter. The LSB of the first byte is '0' indicating an extension address of the address field. The LSB of the second byte is a '1' indicating the end of the address field.

C/R bit indicates whether a frame is a command or a response. The user side will send commands with the C/R bit set to '0' and responses with the C/R bit set to '1'. The network side will do the opposite.

SAPI

The SAPI field identifies the Service Access Point (SAP) where the Data Link Layer services are provided to the layer 3 entities. The SAPI field enables 64 different SAPs to be addressed. Table 6-17 gives an overview of the possible SAPI values.


Table 6-17: Overview of Possible SAPI Values
SAPI RELATED ENTITY

0

Call control procedure

1

Packet communication protocol Q.931

16

Packet communication protocol X.25

63

Data Link Layer management procedures

XX

Reserved for further standardization

TEI

The TEI field identifies the network entity for which the frame is intended or from which the frame is coming. The TEI field allows the addressing of 128 different TEIs.Table 6-18 gives an overview of the possible TEI values.


Table 6-18: Overview of the Possible TEI Values
TEI RELATED ENTITY

0—>63

Non automatic TEI assignment user equipment

64—>126

Automatic TEI assignment user equipment

127

Broadcast TEI

The Control field is two bytes for Information frames and Supervisory frames and one byte for Unnumbered frames. Noted that only the Set Asynchronous Balanced Mode Extended is used.

The FCS is based on a Cyclic Redundancy Check method. It is generated over the Address field, the Control field and the Information field.

Network Layer

The network layer has been described in the I.451 (Q=931) recommendation. The protocol used is D protocol. Figure 6-55 shows the general message structure.


Figure 6-55: General Message Structure

The first three parts are common to all messages and must always be present. The last part is specific for each message type.

Protocol Discriminator

The purpose of the protocol discriminator is to distinguish messages for user-network call control from other messages within this protocol and others standards. Table 6-19 gives an overview of the possible value.


Table 6-19:
VALUE USE

09—>0F

Other messages within L451

10—>3F

50—>FE

X.25 in D-channel

Overview of Possible Values

Call Reference


Table 6-20:
0 0 0 0 Length of Call Reference Value

Flag

Call Reference Value

Call Reference

The purpose of the call reference flag is to identify the call or facility registration. The call reference flag can have the values '0' and '1'. The originating side sets the call reference flag to '0'.The destination side always sets the call reference flag to '1'.

Message type element

The purpose of the message type is to specify the function of the message being sent. The message type is the third part of every message. The message type field consists of one byte. Bit 8 is reserved for extension.

ex: 05 set-up
07 connect

Information Elements

The information elements carry the actual signaling information between the subscriber and the network. For the information elements, two categories are possible.

Single Byte


Table 6-21: Single Byte

1

Information
Identifier

Contents of Information
Elements

Information Element

The MSB is set to 1.This indicates a single byte information element.

Variable length


Table 6-22: Variable Length Information Element

0

Information Identifier

Length (Byte)

Contents

The MSB is set to 0. This indicates a variable length information element.

The information elements are relative to:

Numbering plan

Figure 6-56 shows the numbering plan. I.330 defines the dialing and addressing rules, I.331 defines the numbering plan (E.164).


Figure 6-56:
Numbering Plan

Prefix

The prefix must be used when making an international connection.

Country Code

The country code is used to select the country of destination.

National Destination

The national destination is used to select a geographical location within the selected country.

Subscriber number

The subscriber number is used to identify the user within the selected geographical place.

ISDN Subaddress

The ISDN sub-address is used to identify the user within a certain subscriber number.

FastPadmp and ISDN

Configuration of ISDN is governed by optional software licenses. Corresponding codes are CD (D-channel), CBAS (B-channel with signaling) and PAQD (packet mode on D).

What is supported?

In X.25, the ISDN function (profile 47) connects, in X25, the terminals of the FastPad switches with subscribers via the ISDN and provides a back-up solution when the main line (LL) is out of order or when there is no more LC available. ISDN stack mixed with others functions provides services as Multiple back-up, Dynamic allocation of bandwidth according to overflow thresholds.

By Leased Line, the reader should imagine a direct line between FastPads or over an IPX Frame-Relay network (one LL is composed of network PVC segments). In the second case, the Frame-Relay stack used in front of the IPX is an FRI one since, on the B-channels, only the X.25 protocol is allowed by the FastPad.

Figure 6-57 and Figure 6-58 illustrate different connection types.


Figure 6-57:
Different Connection Types
Note  The terminal adapter must be in transparent mode at 64Kb/s.

Figure 6-58:
Different Connection Type

The ISDN equipment meets the ITU-T requirements concerning ISDN:

Calling Line Identification Presentation (CLIP)-Q.951.3

With this supplementary service, the called party can "see" the ISDN number of the calling party during an incoming call.

Direct Dial In (DDI)-Q.951.1

This supplementary service enables a user to make a direct call to another user on a ISPBX or other private system, without operator intervention.

Sub Address (SA)-Q.951.8

Used to address a specific terminal equipment connected to a bus in multipoint configuration.

Interface

There are two kinds of ISDN kits in the FastPadmp range. One for FRX series and another one for the rest of the range.

For the FRX the S0 plug is a part of the equipment and the kit is composed of two elements which are:

For the rest of the range the ISDN kit has three components:

Note The two kits do not have the same IFS0 interface.

The interface board is plugged on the port in use for the D-channel. The following port numbers (12 modulo) are assigned for the D-channel connection: 0, 3, 6, 9. If n is the number of the D-channel port, then n+1 and n+2 are reserved for the B-channels. If only one B-channel is used then the n+2 port is available for other protocols. In all cases (except for mp6, FRX 3W and 4W), with the external adapter box, the n+1 port is not available even if no B-channel is used (X.25 packet switching on D-channel), because of the physical connection with the back-panel. The following table shows a summary.

Equipment Type

Port Number

S0 / module

S0 / unit

mp6

0

1

-

mp

0, 3, 6, 9

4

-

mp12

0, 3, 6, 9(12 modulo)

4

12

mpr

0, 3(12 modulo)

2 or 4(m2)

8

The S0 interface is in service when power is detected on the phantom circuit is detected. Service parameter 35 (0-255)*200ms is the scanning time, and 36 (0-255) the number of attempts.

Activation is done by parameter 37 (0-255)*200ms. The stand-by mode is done by parameters 38(0-255)*200ms if NT and 39 if TE.

Parameter 56 specifies how many B-channels are used on the BRI:zero when only packet mode is used on D-channel, otherwise one or two. The default value is two.

X.25 Packet-switching on B-channels (X.31case A)

Subscribers, as defined previously, can establish connection with private subscribers behind FastPad devices using X.25 packet-switching on B-channels. This mode of information transfer can also be used to interwork with the PSPDN to connect or to be connected with an X.121 subscriber, by using a specific gateway which assumes the necessary translation between the two networks.

Identification

A device is fully identified according to service parameters. Some of them can be managed by users others depending on the protocol and are assigned and managed by the network.

Protocol Identification at layer 1 must be X.31.This means that for a connection with a TE2 using a TA, this one has always to be in transparent mode at 64Kb/s because no other rate adaptation than X.31 is supported, such as ECMA 102, V110/X30 etc.

Protocol Identification at layer 2 can be either X.25 SLP (single link procedure) or X.25 MLP (multi-link procedure) if the S0 interface, belongs to or is defined within a bundle.

Protocol Identification at layer 3 must be X.25.

Values for LLC are fixed and can not be changed. However, the user is able to act on the behavior of the device according to parameter 74, which defines if LLC is transmitted and/or checked. Its different values are shown in Table 6-23.


Table 6-23: Action on LLC.

Par 74

Different Values

Behavior

transmit

checked

00

no

no

01

yes

no

02

no

yes

03

yes

yes

The user can act on the HLC (parameter 71), as for LLC and more, by choosing which features of tele-services (parameter 73) will be present in the IE's (information elements) according to both standard coding types (parameter 72). The following tele-services are or can be taken into account by the equipment and are illustrated in Table 6-24.


Table 6-24: Tele-Services Taken into Account by the Equipment

Par 73

Par 72

value

feature

value

coding

193

ISO

145

ITU-T

128

unknown

209

national

255

not defined

209

national

Note The values assigned to parameters 72 and 73 depend on each other.

Table 6-25 shows different actions that can be done, concerning the HLC, which are the same as for LLC.


Table 6-25: HDLC Actions That Are the Same for LLC

Par 71

different values

Behavior

transmit

checked

00

no

no

01

yes

no

02

no

yes

03

yes

yes

Parameter 64's value is an index used to define which address in class 10 is assigned to the S0 interface (see Figure 6-59). Up to 36 addresses can be defined.


Figure 6-59:
Parameter 64 Defines Which address is Assigned to SO Interface

When more that one device is connected on the same bus it is useful and better to be able to identify each device. For that there are two possibilities:

    1. SA, can be used by everybody and can have up to 4 digits. The specific character(:) is used as prefix for the SA. A FastPad device can be identified as follows:

    2. by the E.164 address of the basic rate access

    3. by the E.164 and a sub-address

    4. by the sub-address

These three cases are shown in Figure 6-60.

On BRI 41079340, mp A has one S0 connection via port 0 and its SA is 10. mp B has also one connection, but without SA, via its port 0.

On BRI 46299390, mp B has another S0 connection via port 3. It is identified by its own SA which is 1890.


Figure 6-60: Example

The corresponding configuration is the following (See Table 6-26).


Table 6-26:

M c x A

M c x B

Class 12 rec 0

0 47 default profile

1 64,0 raw 0 in C10

2 62,1 SA used

0 47

1 64,0

2 62,0 SA not used (default value)

Class 12 rec 3

0 47

1 64,1 raw 1 in C10

2 62,1

Class 10 rec 0

0 41079340:10

0 41079340

1 :1890

Configuration

The next sheet shows a Set-up capture.

SAPI TEI FType Q921 Ty Q931 Msg *

0 64 INFO SETUP

08000000008910892086048333333337

010081154280813E410CA00462993900

Chan SAPI c TEI FType Ns Nr P *

r F *

TE 0 0 64 INFO 0 0 0

PrD CRL Ref CF Q931 Msg FrTime F*

8 1 0 0 SETUP 9506 G

1

0089 Len CS

4280

Bearer Capability 2 0

Coding Std.................ITU-T

Info Trans Cap.....Unres Digital

Transfer Mode............Circuit

Transfer Rate..........64 Kbit/s

108 Len CS

813

Channel Identification 1 0

Interface Id Present..Implicitly

Interface Type.............Basic

Channel................Preferred

D-channel.....................No

Channel Selected.............Any

9 Len CS

E

Shift 0

Shift Type...........Non-Locking

Codeset........................6

208 Len CS

410

Undefined Element 1 6

604833333333 Len CS

CA0046299390

Calling Party Number 10 0 Set-up sent by the FastPad with default

Number Type...........Subscriber HLC & LLC

Number Plan..............Unknown

Presentation.............Allowed

Screening...User Prov Unscreened

Number Digits

46299390

70833333333 Len CS

09041079340

Called Party Number 9 0

Number Type..............Unknown

Number Plan..............Unknown

Number digits

41079340

7089ACE Len CS

C580966

Low Layer Compat. 5 0

Coding Std.................ITU-T

Info Trans Cap.....Unres Digital

Transfer Mode............Circuit

Transfer Rate..........64 Kbit/s

Layer Id.................Layer 1

Proto Id....................X.31

Layer Id.................Layer 2

Lay 2 Proto......X.25 Link Layer

Layer 2 information

E

6

709C Len CS

D211

High Layer Compat. 2 0

Coding Std.................ITU-T

Interpret....First High Lay Used

Pres Method...Hi Lay Prot Profil

Hi Lay Char.............OSI Appl

A Len CS

    1. Sending Complete 0

    2. DDI, can be used only if the user subscribes to this supplementary service (Telecom company, ISPBX). The last digits, one or more according to the subscription, of the ISDN number can be different.

Suppose now, the ISDN number of a basic rate access is 46299390 and the DDI behavior is subscribed for five; the following E.164 address will identify a single BRI (See Figure 6-61).


Figure 6-61:
E.164 Address Identifies a Single BRI

The configuration for this example is:


Table 6-27: Configuration

M P

Class 12 rec 0

0 47

1 64,0

2 63,1 DDI behavior

Class 10 rec 0

0 46299391

In fact DDI is useful behind an "intelligent" NT2, such as ISPBX. For example see Figure 6-62.


Figure 6-62: Example

DDI's numbers are assigned to the Primary rate interface from the point of view of the network. The ISPBX is able to send the incoming Set-up on the correct BRI. Each device connected in a multipoint configuration can use the sub-addressing system to be identified.

Note The E164 address, when configured in Class 10, becomes the calling address of the TE. It means that two calling address fields will be present in the Set-up. One provided by the network and another one provided by the TE.

Principle

Mapping table

To establish a connection over ISDN network between two entities, it is necessary to map two different numbering plans. An X.121 address (max 15 digits) in (C22 rec0) with an E.164 address (max 28 digits) in (C22 rec 1), as shown in Figure 6-63.


Figure 6-63: Example

The corresponding mapping table in the configuration will be:

mp A

mp B

Class 22 rec 0

0 800010

0 900000

Class 22 rec 1

0 46299390

0 41079340

Behavior

Each remote ISDN point is linked to a behavior (C22 rec2) and an X.25 profile (C30 rec (0-15)). It is also possible to define up to five optional actions. The structure of Class 22 rec2 is the following:

Class 22 rec 2

0 Byte 0, Byte 1, Byte 2, and up to five optional actions.

Byte 0.

Defines the way the connection can be established. The three different values that can be used are:

Byte 1.

This byte is in fact an index, used to define which recurrence will be used in Class 30. In this way a X.25 profile is assigned dynamically on a B-channel according to the remote ISDN number. An X.25 profile can be used by different ISDN numbers as soon as the X.25 service parameters are compatible. Up to 16 different connection profiles can be defined in class 30.

Byte 2.

This byte is not used and is always set to 00.

The example in Figure 6-63 could be now as followed in Figure 6-64. The configuration could be as shown in Table 6-28.


Figure 6-64: Example

From 9000 00 it is only possible to reach 8000 10.

From 8000 10 it is impossible to reach 9000 00.

Between 1005 68 and 80010 the establishment phase can be initiated by both.


Table 6-28: Configuration

mp A

mp B

mp C

Class 1 rec 2

0 900000

0 800010

0 100568

Class 10 rec 0

0 41079340

0 46299390

0 54891204

Class 22 rec 0 - X.121 @ -

0 800010

1 100568

0

0 800010

Class 22 rec 1 - E.164 @ -

0 46299390

1 54891204

0 41079340

0 46299390

Class 22 rec 2

0 60,00,00

60 for outgoing

00 for rec 0 in C30

00 because not used

0 50,00,00

50 for incoming

00 for rec 0 in C30

1 70,00,00

0 70,01,00

70 for both-way

01 for rec 1 n C30

Class 30 rec 0

0 4

DTE logical profile

0 5

DCE logical profile

Class 30 rec 1

0 4

As explained previously, for node 8000 10 two different ISDN remote points use the same X.25 profile, here profile 5.

When there is no more switched virtual circuit on a B-channel, this one is disconnected after a time-out defined by parameter 60(1-250)*1s. The default value is zero and means no time out.

For an outgoing call, the most important address is the X.121 address (Class 22 rec0).

For an incoming Set-up, the most important address is the E.164 address (Class 22 rec1).

Up to 250 different mappings can be defined in class 22.

Optional actions.

An action is a one byte coded by quartet. The MSB quartet defines the action type, the LSB quartet defines the value assigned to the action. There are six different actions for ISDN, some of its refer to specific paragraph. When an action is not mentioned, the behavior is the default one.

Specific characters

Certain characters can be used instead of some digits within an address or to replace a complete one. Table 6-29 lists characters and their meanings.


Table 6-29: Specific Characters Used Instead of Digits Within an Address

Characters

meaning

> *

indicates an offset and is used for extraction

=

used to mask any digits within an address

;

used to replace any address

:

used as a separator, prefix to indicate a SA

* For more information on extraction refer to next sheet.

As seen in the behavior; one can choose the manner of a Set-up: incoming, outgoing, or both-way. The use of these characters depends on this behavior, as shown in the following example.


Figure 6-65:
Example


Table 6-30:

Class 22 rec 0

Class 22 rec 1

Class 22 rec 2

0 12345678

0 41079340

0 60,00,00

1 378

1 99891604:0001

1 70,00,00

2 456= = =

2 46299390

2 70,00,00

3 ;

3 36122018

3 70,00,00

4

4 12 = =

4 50,00,00

5

5 ;

5 50,00,00

Configuration

0 = Mapping between a X.121 @ and an E.164 @, for an outgoing Set-up.

1 = Any X.121 @ beginning with the digits 378 will generate a Set-up with the corresponding E.164 @. Incoming Set-ups, for the specified E.164 address, are accepted. The length of the X.121 address does not matter.

2 = Same behavior as in case(b) but here the length is checked.

3 = Any X.121 @ will generate the Set-up. Incoming Set-ups, for the specified E.164 address, are accepted.

4 = Any E.164 @ beginning with 12 followed by two more digits will be accepted.

5 = Any E.164 @ will be accepted.

Extraction case. The E.164 address is built from a part of or the complete X.121 address.This can be useful when the user is building his or her own network from scratch. Otherwise, for a network already having a numbering plan, it is more tricky to use.

The extraction uses two tools:

1 = >, which is a specific character and indicates an offset position within an X.121 address.

2 = A4 or Action 4x, is used to specify, from the offset, the number of digits (value of x(0-f)) to extract, to form the E.164 address.

Table 6-31 illustrates some examples.


Table 6-31: Examples

Class 22 rec 0

Class 22 rec 1

Class 22 rec 2

0 9025>

0 4512

0 70,00,00,44

1 41079340

1

1 60,00,00,48

2 12345>

2 462993

2 70,00,00,42

3 ;

3

3 60,00,00,48

0 = Extraction of four digits after the offset. If the called X.121 address is 902512345, the called E.164 address will be 45121234.

1 = Extraction of eight digits from the beginning because no offset is specified. The E.164 address will be 41079340.

2 = Extraction of two digits after the offset. For this X.121 address,1234578, the E.164 address will be 46299378.

3 = Extraction of eight digits from the beginning of any X.121 address. If the called X.121 address is 1789101012, the E.164 address will be 17891010.

Note Extraction works for an outgoing call, using an X.121 address as the basis for building the E.164 address. In the case of zero and two, the incoming Set-up is accepted respectively for the E.164 addresses 4512 and 462993.

Table 6-32 shows in which cases it can be used. DC means Do not Care.


Table 6-32:

Specific character

Incoming

Outgoing

C22 rec0

C22 rec1

C22 rec0

C22 rec1

>

DC

/

yes

/

=

DC

yes

yes

DC

;

DC

yes

yes

DC

:

/

yes

/

yes

Cases

Multiple backup

Sometimes the remote ISDN point can be busy, or out of order. That is why it is useful to have more than one E.164 address for each X.121 address. This principle is called multiple backup. For one X.121 address there is a list of a maximum of 10 E.164 addresses.

To use multiple backup, it is necessary:

1 = To add action types, in the behavior(C22 rec 2).

2 = To use parameters 65,66,67,68 of the ISDN profile (profile 47).

When, for a X.121 address, the call request must be sent towards the ISDN network, the system looks for the corresponding E.164 address and checks if action five is present. If yes, it means there is a list for this X.121 address and the mapping table is scanned from top to bottom.

Each E.164 address is stored in a temporary table according to its priority and its position during the scrolling of the mapping table.

With the priority, the order within a list can be changed at any time.

Figure 6-66 illustrates this principle.


Figure 6-66: Principle

From 9000 00, the user can reach a subscriber "Z" via node 7000 10 and then 7000 20 using the leased line 0. If a problem appears on line 0, there are backup solutions over ISDN with two E.164 addresses to reach the subscriber "Z" which belongs to the area 7000.

From 9000 00, it is also possible to reach area 6000 and 5001 via ISDN number X and Y.

The mapping table in node 9000 00 would be, as follows.

Class 12 rec 3

Class 22 rec 0

Class 22 rec 1

Class 22 rec 2

0 47

1 65,5

2 66,10

3 67,3

4 68,100

0 7000

1 7000

2 6000

3 5001

0 B

1 D

2 X

3 Y

0 70,00,00,5

1 70,00,00,61

2 70,00,00

3 70,00,00

The list for backup over ISDN is:

1) address B, with 2 attempts.

2) address D, with 1 attempt. A Set-up will be sent only if the two B-channels of the BRI "B" are busy or if the node 7000 10 is out of order. A backup of nodes or parts of network is possible, as for a leased line.

After sometimes another ISDN number is included in the list and the first choice is changed, it will be number D. Always for node 9000 00 the configuration would be now the following.


Table 6-33: Configuration

Class 12 rec 3

Class 22 rec 0

Class 22 rec 1

Class 22 rec 2

0 47

0 7000

0 B

0

1 65,5

1 7000

1 D

70,00,00,52,70

2 66,10

2 6000

2 X

1

3 67,3

3 5001

3 Y

70,00,00,52,71

4 68,100

4 7000

4 C

2 70,00,00

3 70,00,00

4 70,00,00,61

The list to back up the connection with 7000 will be:

1) D, with two attempts. D is first because it has the highest priority.

2) B, with two attempts.

3) C, with one attempt.

The general parameters are the default ones and are not changed. There will be 5s between each attempt, 3 cycles with 10 s between each.

Incoming process

On an incoming call the following processes are executed, when Bearer, Low layer Compatibility and High Layer Compatibility are accepted.

The process is shown in Figure 6-67.

If DDI is specified in the subscription and the FastPad doesn't use it, we accept all the ISDN numbers and check only the sub-address.


Figure 6-67: Incoming Process

Outgoing process

Hypothesis: one B-channel is already used.

The decision to multiplex a call is made on an outgoing call, according to the E.164 address.

The called address is compared with the remote user address of the B-channels already connected.

If the comparison is right, the sub-addresses are compared, otherwise another B-channel is opened.

If there is no sub-address within the called address, we think we want to reach a device connected to the first remote ISDN point and we do not care about a previous Sub-address in the first call.

If both sub-addresses are present and identical, or both absent, we multiplex the call on the same B-channel.

In all others cases another B-channel is opened.

Routing

The port which defines the D-channel is used by the routing function to send the Set-up. It is also possible to define the first choice as being one port used by a B-channel. However, in this case you must note the destination of the first call, so as to be able to activate back-up.

Internetworking with PSPDN (using X.31 case A)

There is a way to use X.25 packet switching on B-channels to interconnect FastPad's subscribers or PVDN over ISDN and PSPDN networks.The condition is the existence of a gateway between both networks.

A common E.164 address can be used by everybody to make a call from ISDN towards PSPDN. Specific addresses, for specific customers, can be assigned on request by the Telecom company if need be. Anyhow the called site must subscribe to the reverse charging facility.

For a call from PSPDN towards ISDN, the called address, in deed the E.164 address of the remote ISDN point, is preceded by a prefix which indicates this call must be routed towards the gateway. Just a sub-address will be present in the called address field of the X.25 call request generated by the gateway on the B-channel.

Figure 6-68 illustrates this kind of connection.


Figure 6-68: Connection Illustration

If subscriber A wants to reach B, there will be two steps in the network:

1) Set-up over ISDN with the address is 36086464. A point-to-point connection is established with the gateway.

2) A call request is sent with the address 1921309102.

If subscriber B wants to reach A, there will be three steps in the network.

1) B sends a call request with the address 43 41079340 05.

2) The gateway sends a Set-up over ISDN with the address 41079340.

3) The gateway sends a call request on a B-channel with the address 05.

For the node 196810 the configuration would be:

Class 22 rec 0

Class 22 rec 1

Class 22 rec 2

0 19213= =

0 36086464

0 70,00,00

Before going too far

Type of line, are the following: 14 for D-channel, 15 for B-channels

Type of profile, are the following: 47 for D-channel in C12

Anyone for B-channel in C12 because those are dynamically assigned in function of the remote E.164 address and are defined in C30. However as soon as more than one logical group channel is used those ones will must be defined also in C12 because the buffers are reserved at the initialization of the equipment according to C12.

Type of access, the access is always a BRI with TE behavior.

Type of ISDN. ISDN has not been implemented at the same time and does not follow all the specifications of ITU-T. Within a country the ISDN network is changing step-by-step and sometimes BRI doesn't have the same level of implementation (Digital Version). That is why in the ISDN profile there are two parameters to specify in which country and with which Digital Version the equipment must be configured.

In Europe, countries try to have a network meeting the requirements of ETSI. In some countries it is necessary to pass tests to be allowed to be connected on its ISDN networks, when ETSI's requirements are not met. There are specific values to set in the ISDN profile where FastPad equipment has been approved.

0 for France

1 for United Kingdom

2 for Switzerland or Netherlands

3 for ETSI

0 DN2 in France

1 DN3 in France

Switzerland

Netherlands

2,2

44,0

48,4

49,30

51,10

2,2

44,0

48,4

49,30

51,60

TEI assignment on In & Out set-up

T303

T305

T310

Normally we do not must change the parameter's value of LAP-D and D protocol.

Examples

Point-to-point connection

The connection between Paris, France and Nijmegen, the Netherlands, using a leased line, is backed up using the ISDN network.The Basic Rate Interface in France follows the ETSI requirements and the national ones in Netherlands. The access node in Nijmegen will used the sub-address 1005. Each access can use two B-channels if need be and the connection can be established by both sites. The length of the X.121 address will be checked.


Figure 6-69:
Point-to-Point Connection

The complete address for the node located in Nijmegen is: 19 0931 80 884026:1005.

Prefix 19, for outgoing call from France to a foreign country.

Prefix 0931, to identify the Netherlands.

Prefix 80, to indicate the town of Nijmegen.

Address of the BRI is 804026.

Sub-address 1005 identifies the device connected on the bus.

The complete address for the node located in Paris is: 09 33 1 46299390.

Prefix 09, for an outgoing call from Netherlands to a foreign country.

Prefix 33, to identify France.

Prefix 1, to indicate the Parisian area.

Address of the basic BRI is 46299390.

Table 6-34 shows this configuration.


Table 6-34: point-to-point configuration

Node: 9000 00

Node: 8000 10

Class 1 rec 1

0 14 Type of line for D-channel

1 15 Type of line for B-channels

2 15

3 1

0 14

1 15

2 15

3 1

Class 12 rec 0

0 47 ISDN profile

1 2,3 Country; Euro-ISDN(ETSI)

2 64,0 Raw in C10 for the E.164 @

default values

56,2 Number of B-channels

0 47 ISDN profile

1 2,2 Country; 2 for Netherlands

2 44,0 TEI allocation at START up

3 48,4 t 303

4 49,30 t 305

5 51,60 t 310

6 62,1 Sub-address is used

7 64,0 Raw in C10

default values

56,2

Class 12 rec 3

0 4

0 5

Class 10 rec 0

0 46299390

0 884026:1005

Class 22 rec 0

0 8000 = = = =

0 900000 = =

Class 22 rec 1

0 19093180884026:1005

0 0933146299390

Class 22 rec 2

0 70,00,00

70: Set-up in the both way.

00: Rec 0 in C30

00: Not used

0 70,00,00

Class 30 rec 0

0 5

1 22,1

2 23,2

0 4

1 22,1

2 23,2

Class 9 rec 0

0 8000

0 9000

Class 9 rec 1

0 2,2,0,3,0

0 2,2,0,3,0
Note In a digital network such as ISDN, the scanning time (by default 6s) to declare an analog line in service, can be decreased and set to 200ms.

Multipoint connection

TE1 can reach both nodes. For Paris, the connection can be established from both sites. For Nijmegen only from TE1. TE1 is located outside the Parisian area. The B-channel is cleared after a time out of 10s. See Figure 6-70.


Figure 6-70: Multipoint Connection

The X.25 TE1 works in two addresses mode. The X.25 profile number 2 is used. The configuration is the following (See Table 6-35).


Table 6-35: Configuration

Node: 9000 00

Node: 8000 10

Class 1 rec 1

0 14 Type of line for D-channel

1 15 Type of line for B-channels

2 15

3 1

0 14

1 15

2 15

3 1

Class 12 rec 0

0 47 ISDN profile

1 2,3 Country; Euro-ISDN(ETSI)

2 64,0 Raw in C10 for the E.164 @

3 60,10 Time out for 0cv on B.

default values

56,2 number of B-channels

0 47 ISDN profile

1 2,2 Country; 2 for Netherlands

2 44,0 TEI allocation at START up

3 48,4 t 303

4 49,30 t 305

5 51,60 t 310

6 62,1 Sub-address is used

7 64,0 Raw in C10

8 60,10

default values

56,2

Class 12 rec 3

0 4

0 5

Class 10 rec 0

0 46299390

0 884026:1005

Class 22 rec 0

0 8000 = = = =

1 1379

0 900000 = =

1

Class 22 rec 1

0 19093180884026:1005

1 41079340

0 0933146299390

1 093341079340

Class 22 rec 2

0 70,00,00

70: Set-up in the both way.

00: Rec 0 in C30

00: Not used

1 70,01,00

01: Rec 1 in C30

0 70,00,00

1 50,01,00

50: Incoming Set-up

01: Rec1 in C30

Class 30 rec 0

0 5

1 22,1

2 23,2

0 4

1 22,1

2 23,2

Class 30 rec1

0 2

1 2,0

2 22,1

3 23,2

2 45,2

0 2

1 2,0

2 22,1

3 23,2

4 45,2

Class 9 rec 0

0 8000

1 1379

0 9000

1 1379

Class 9 rec 1

0 2,2,0,3,0

1 1,1,0,0

0 2,2,0,3,0

1 1,1,0,0

Multiple Back-Up

There is already a back-up solution over ISDN when the leased line is out of order. But if the remote access of node 800010 or the node itself is also out of order, another back up solution is possible with node 800020 (see Figure 6-71).

The number of attempts for the first E.164 address of the list will be equal to 2 and 1 for the last one.

The values for the time-out and number of cycles are the default ones.


Figure 6-71: Multiple Back-up

The configuration is now as follows.


Table 6-36:

Node: 9000 00

Node: 8000 10

Class 12 rec 0

0 47 ISDN profile

1 2,3 Country; Euro-ISDN(ETSI)

2 64,0 Raw in C10 for the E.164 @

3 60,10 Time out for 0cv on B.

default values

56,2 number of B-channels

65,5 time out between attempts

66,10 time out between cycle

67,3 number of cycle

68,100 max time out for the multiple back up

0 47 ISDN profile

1 2,2 Country; 2 for Netherlands

2 44,0 TEI allocation at START up

3 48,4 t 303

4 49,30 t 305

5 51,60 t 310

6 62,1 Sub-address is used

7 64,0 Raw in C10

8 60,10

default values

56,2

Class 22 rec 0

0 8000 = = = =

1 1379

2 8000 = = = =

0 900000 = =

1

Class 22 rec 1

0 19093180884026:1005

1 41079340

2 19093180884232

0 0933146299390

1 093341079340

Class 22 rec 2

0 70,00,00,52

70: Set-up in the both way.

00: Rec 0 in C30

00: Not used

52: 2 attempts for the E.164 @ in raw 0 rec1

1 70,01,00,

01: Rec 1 in C30

2 70,00,00,61

61: 1 attempt for the last E.164 @ of the list

0 70,00,00

1 50,01,00

50: Incoming Set-up

01: Rec1 in C30

Class 30 rec 0

0 5 X25 DCE trunk

1 22,1

2 23,2

0 4 X25 DTE trunk

1 22,1

2 23,2

Class 30 rec1

0 2 X25 private

1 2,0

2 22,1

3 23,2

2 45,2 2 @ mode

0 2

1 2,0

2 22,1

3 23,2

4 45,2

Class 9 rec 0

0 8000

1 1379

0 9000

1 1379

Class 9 rec 1

0 2,2,0,3,0

1 1,1,0,0

0 2,2,0,3,0

1 1,1,0,0

Configuration

For node 800020 it will be:

class 12 rec 0

0 47

1 2,3

2 64,0 raw 0 in C10

3 63,1 DDI behavior

class 10 rec 0

0 884230

Internetworking with PSPDN

The E.164 address of the gateway(G) is 36086464. According to the way of the call the gateway uses two different profiles as follows:

From ISDN to PSPDN a DCE logic.

From PSPDN to ISDN a DTE logic.

The interworking is allowed only with node 900000. Node 7000 is located in PARIS.

See Figure 6-72 for an example.


Figure 6-72:
Example

When subscriber A would like to reach the internal function of node 7000, he will must call with the address 19213037499Dxxyy.

From node 7000 subscriber B will must call with the address 4314629939099Dxxyy.

In the configuration the following has been added (bold).


Table 6-37: Configuration

Class 22 rec 0

0 8000 = = = =

1 1379

2 8000 = = = =

3 192

4

0 900000 = =

1

Class 22 rec 1

0 19093180884026:1005

1 41079340

2 19093180884232

3 36086464

4 36086464

0 0933146299390

1 093341079340

Class 22 rec 2

0 70,00,00,52

70: Set-up in the both way.

00: Rec 0 in C30

00: Not used

52: 2 attempts for the E.164 @ in raw 0 rec1

1 70,01,00,

01: Rec 1 in C30

2 70,00,00,61

61: 1 attempt for the last E.164 @ of the list

3 60,02,00

02: Rec 2 in C30 ISDN to PSPDN

4 50,03,00

03: Rec 3 in C30 PSPDN to ISDN

0 70,00,00

1 50,01,00

50: Incoming Set-up

01: Rec1 in C30

Class 30 rec 0

0 5 X25 DCE trunk

1 22,1

2 23,2

1 22,1

2 23,2

0 4 X25 DTE trunk

Class 30 rec1

0 2 X25 private

1 2,0

2 22,1

3 23,2

2 45,2 2 @ mode

0 2

1 2,0

2 22,1

3 23,2

4 45,2

Class 30 rec2

0 0 PSPDN profile(DTE)

1 11,16 16 both-way Svc

2 13,17

3 48,0 No CUG

4 49,0 No reverse charging

5 54,0 No fast select

6 56,1 Throughput negotiation

Class 30 rec3

0 1 X25 DCE profile

1 11,1 1 bothway Svc

2 5,1

3 48,0 No CUG

4 49,0 No reverse charging

5 52,1 PSPDN behavior

6 54,0 No fast select

7 56,1 Throughput negotiation

Class 9 rec 0

0 8000

1 1

0 9000

1 1379

Class 9 rec 1

0 2,2,0,3,0

1 1,1,0,0

0 2,2,0,3,0

1 1,1,0,0

Routing is done for the TE1 and node 7000 on the first digit of the X.121 address.

Call in loop

Some times to check a BRI, a call-in loop can be very useful (Figure 6-73).


Figure 6-73: Call In Loop

The mp address is 900000.

Subscriber A will call its own traffic generator with the X.121 @ 80000099D00GG. This call will be sent towards port 0. The mapping for 8000 will be its own E.164 @.

On the BRI two B-channels will be used, one for the outgoing set-up, the second one for the incoming set-up. For the B-channel used for the incoming set-up there is an address conversion of the called address (8000 in 9000).

Two different X.25 trunk profiles are used, as shown in Table 6-38.


Table 6-38: X.25 Trunk Profiles

class 1 rec 1

class 9 rec 7

0 14

1 15

2 15

0 1,1,0,0

class 12 rec 0

class 9 rec 11

0 47

1 2,3

2 64,0

0 8000

1 9000

class 22 rec 0

class 10 rec 0

0 8000

1

0 41079340

class 22 rec 1

0 41079340

1 ;

class 22 rec 2

0 60,00,00

1 50,01,00

class 30 rec 0

0 4

1 22,1

2 23,1

class 30 rec 0

0 5

1 22,1

2 23,1

3 89,2

tab I3.26

The next picture (Figure 6-74) is a diagram of the establishment phase on D-channel for a call between to devices connected on the same bus. One device is calling the other one. We have a call-in loop, but between to different devices.


Figure 6-74: Diagram of Establishment Phase on D-channel

Both devices A and B have been already connected to the bus and the network checks the TEI assignment with a Check-Request. Devices A and B answer with respectively TEI 66 and 64. A wants to reach B and sends an outgoing Set-up. There is a incoming broadcast Set-up. B detects that this Set-up is for it and establishes the Data Link Level for answering the NT. The next two pages are a screen capture of this exchange.

**** HP 4952 Printer Output ****

SAPI TEI FType Q921 Ty Q931 Msg *

63 127 UI ChkReq *

FF00000F *

EF3F004F *

63 127 UI ChkRes

FF002808

CF3F7151

63 127 UI ChkRes

FF000F08

CF3F2E55

0 66 SABME

087

05F

0 66 UA *

087 *

053 *

0 66 INFO SETUP

08000000008992086083333333360853

050081154280E410C9046299390D3001

0 66 RR *

0800 *

0512 *

0 66 INFO CALL PROC*

08000080108 *

25028112819 *

0 66 RR

0800

2512

0 127 UI SETUP *

0F000000089108608333333336028333*

2F381154280812C9046299390CB03146*

0 64 SABME

087

01F

0 64 UA *

087 *

013 *

0 64 INFO CONNect

080000809208

01008117E410

0 64 RR *

0800 *

0112 *

0 64 INFO CONN ACK *

08000000 *

2102811F *

0 64 RR

0800

2112

0 66 INFO CONNect *

08000080 *

25228117 *

0 66 RR

0800

2514

0 64 RR *

0800 *

2113 *

X.25 Packet Switching on D-channel (X.31 case B)

Principle

This service offered by the Telecom companies provides a point-to-point connection, a so-called Permanent Logical Link (PLL), between the BRI and the Packet Handler (PH). The PH can route any X.121 call request coming from a BRI or PSPDN subscriber.


Figure 6-75:
X.25 Packet Switching on D-channel

Several PLL can be defined on BRI, up to four in France and up to eight in Spain. But only 9,6Kb/s of the D-channel's bandwidth, which is 16kb/s, can be used for PLL's.

Users must subscribe to this service and a PLL is defined as followed:

In fact, each PLL is like a PSPDN access multiplexed on BRI. On D-channel the frame format is:

LAPD

X25

DATA

FCS

The Service requested is Packet Mode on D, so the Service Access Point must be identified and the corresponding SAPI's value is 16.

Before being processed by the PH, each frame passes through the Frame Handler. The FH will do the translation between the two different Data Link Levels.

This kind of connection is useful for transactional applications.

Configuration

On the FastPad the routing function uses the line number to know which one it must send a call on. That is why a PLL is always linked to a Virtual Line. The virtual line uses a X.25 profile which follows the X.25 service parameters defined at subscription.

As mentioned previously, a BRI can provide several PLL. Parameter 43 in the ISDN profile (47) defines the number of PLL for one S0 interface connection. This parameter refers to numbers of TEI by SAPI 16. Numbers of TEI because one PLL has its own TEI defined at the subscription and SAPI 16 to identify the SAP. Figure 6-76 shows how PLL connection can be represented on the FastPad.


Figure 6-76: PLL Connection Represented on the FastPad

After that the number of PLL to use on a S0 has been set, each PLL must be fully defined. For that, an extension profile is used in class 13 of the port used for the D-channel. This profile is also number 47. The PLL's connections are managed by a function called DLM, which stands for Dynamic Line Management. It is necessary to activate this function in class 3 rec 15.

Within this profile each PLL is identified by:

The structure of profile 47 in C13 is the following:

Where n corresponds to the number of PLL defined according to the value of parameter 43.

The following example illustrates an mp having two PLL accesses on an S0 connection.


Figure 6-77:
mp with Two PLL Accesses on an SO Connection

Here, no B-channel can be used on the S0 access. To reach the mp, located in Paris, the first choice is over PLL1 and PLL2 is the back-up. The configuration is the following (Table 6-39)


Table 6-39: Configuration

Class 12 rec 0

Class 13 Rec 0

Class 30 rec 0

Class 30 rec 1

0 47

1 43,2 2 PLL

2 56,0 no B-channel

0 47

2 160 VL

3 1 TEI of PLL1

4 0 Rec 0 in C30

10 161 VL

11 2 TEI of PLL2

12 1 REC 1 in C30

0 0 PSPDN

profile

1 53,0 Raw 0 in C10

2 45,2 2 @ mode

0 0

1 53,1 Raw 1 in C10

2 45,2

Class 10 rec 0

Class 9 rec 0

Class 9 rec 0

Class 3 rec 15

0 12345678

1 87654321

0 192

0 4,2,0,160,161

0 1,GL

The PLL setting phase can be established in two ways. At start-up or upon an incoming or outgoing call request.This choice is made according to parameter 70. If set to zero, it means at start-up, if set to one it means upon outgoing or incoming call request.

The setting phase diagram (Figure 6-78) is as follows:


Figure 6-78: Setting Phase Diagram

The PLL remains in Data Tansfer Mode.

However, there is an option that makes the PLL be a Half Permanent Logical Link. For that, there is time-out. This is parameter 69 (1-250s). When there is no more switched virtual circuit established, the PLL is in disconnect mode, as shown in Figure 6-79.


Figure 6-79: Phase Diagram

When 69 is set to 0, the timer is not activated. If 69 is not set to zero, parameter 70 will must be set to one.

Management functions

Telemaintenance

In case of an ISDN S0 interface, only loop L0 on D-channel can be tested.

On a B-channel, the loop tests can not be used.

The syntax is T LIxx B0 where xx corresponds to the D-channel.

It is also possible to use the disconnect and disconnect option.

The syntax is T LIxx D or T LIxxC.

Ex:

*90006899D12MM

COM

CALL CONNECTED

T LI00D

9000 680A 2D0F 11B5 B11A FF0C 0000 0000 0000 0000 0000 0000 0000 0000 0000

TEST ENDED WITH NO ERROR

T LI00C

9000 680A 2D65 11B5 B11A FF0C 0000 0000 0000 0000 0000 0000 0000 0000 0000

TEST ENDED WITH NO ERROR

To test a switched connection or back-up solution, there is the possibility to open a connection by using this command: CIyyX@X.121

Ex: to reach node 8000 towards S0 access on port 0.

CI00X80000099

9000 0010 24C4 117F B142 FF0C 0000 0000 0000 0000 0000 0000 0000 0000 0000

TEST ENDED WITH NO ERROR

Statistics

On D-channel EI / HI . In the display EI 000 is shown for a connection with B-channels and EI xxx if packet mode on D used, where xxx indicates the sum of all Svc established on PLL's.

On B-channels EI / HI.

Example 1 shows a connection within one B-channel.

Example 2 shows a connection on D-channel.

Example 1

*90006899D14SS

COM

CALL CONNECTED

I

EQT No : 900068

D: 29/05/92 H: 09/38/14

BUFC:5215

BUFF:4814

COM : 0001

PKTS SWITCHED:0001

FR SWITCHED : 0000

PROG:V 11.1.1.05

CONF:V 26

MODULE STATE M0:ES-OP M1:HS M2:HS

LINE STATE AND NO. OF LCS

00 EI 000 01 EI 001 02 HI 03 ES 000

04 NC 05 HA 06 NC 07 NC

08 NC 09 NC 10 NC 11 NC

12 NC 13 NC 14 NC 15 NC

16 NC 17 NC 18 NC 19 NC

20 NC 21 NC 22 NC 23 NC

24 NC 25 NC 26 NC 27 NC

28 NC 29 NC 30 NC 31 NC

32 NC 33 NC 34 NC 35 NC

Example 2

*90006899D14SS

COM

CALL CONNECTED

I

EQT No : 900068

D: 29/05/92 H: 09/38/14

BUFC:5215

BUFF:4814

COM : 0001

PKTS SWITCHED:0001

FR SWITCHED : 0000

PROG:V 11.1.1.05

CONF:V 26

MODULE STATE M0:ES-OP M1:HS M2:HS

LINE STATE AND NO. OF LCS

00 EI 001 01 HI 02 HI 03 HS

04 NC 05 HA 06 NC 07 NC

08 NC 09 NC 10 NC 11 NC

12 NC 13 NC 14 NC 15 NC

16 NC 17 NC 18 NC 19 NC

20 NC 21 NC 22 NC 23 NC

24 NC 25 NC 26 NC 27 NC

28 NC 29 NC 30 NC 31 NC

32 NC 33 NC 34 NC 35 NC

Observation

Observation on the D-channel is possible. Example 1 is an observation of a connection over ISDN using B-channels. Example 2 is for a connection in packet mode using D-channel.

On B-channels, it is like an X.25 line.

On a Virtual Line, it is like an X.25 line

Example 1:

*70001099D04OO0099

COM

CALL CONNECTED

7000 1009 7DA4 16CA B10B FF04 0000 0008 FCFF 030F 6B46 01FF

7000 1009 7DA4 16CA B10B FF04 0001 0008 FEFF 030F 6B46 0283

7000 1009 7E19 16CA B10B FF04 0000 0003 0083 7F

7000 1009 7E19 16CA B10B FF04 0001 0003 0083 73

7000 1009 7E19 16CA B10B FF04 0000 0042 0083 0000 0801 0105 A104 0288 9018 0183

6C0A 2180 3436 3239 3933 3930 6D06 8050 3139 3638 7009 8134

7000 1009 7E1A 16CA B10B FF04 0001 0004 0083 0102

7000 1009 7E1D 16CA B10B FF04 0001 000B 0283 0002 0801 8102 1801 8A

7000 1009 7E1D 16CA B10B FF04 0000 0004 0283 0102

7000 1009 7E25 16CA B10B FF04 0001 0008 0283 0202 0801 8107

7000 1009 7E25 16CA B10B FF04 0000 0004 0283 0104

7000 1009 7E89 16CA B10B FF04 0001 0004 0283 0103

7000 1009 7E89 16CA B10B FF04 0000 0004 0283 0105

7000 1009 7EB1 16CA B10B FF04 0001 0008 FEFF 030F 41C6 0287

7000 1009 7EED 16CA B10B FF04 0001 0004 0283 0103

7000 1009 7EED 16CA B10B FF04 0000 0004 0283 0105

7000 1009 7F51 16CA B10B FF04 0001 0004 0283 0103

7000 1009 7F51 16CA B10B FF04 0000 0004 0283 0105

7000 1009 7FB5 16CA B10B FF04 0001 0004 0283 0103

7000 1009 7FB5 16CA B10B FF04 0000 0004 0283 0105

7000 1009 8019 16CA B10B FF04 0001 0004 0283 0103

7000 1009 8019 16CA B10B FF04 0000 0004 0283 0105

7000 1009 807D 16CA B10B FF04 0001 0004 0283 0103

7000 1009 807D 16CA B10B FF04 0000 0004 0283 0105

7000 1009 80BE 16CA B10B FF04 0001 001E 0283 0402 0801 8145 0802 8790 2007 0032

342A 0100 0020 0700 3438 2A00 0000

7000 1009 80BE 16CA B10B FF04 0000 0004 0283 0106

7000 1009 80BE 16CA B10B FF04 0000 000C 0083 0206 0801 014D 0802 80E3

7000 1009 80BE 16CA B10B FF04 0001 0004 0083 0104

7000 1009 80C1 16CA B10B FF04 0001 000C 0283 0604 0801 815A 0802 8790

7000 1009 80C1 16CA B10B FF04 0000 0004 0283 0108

7000 1009 80C1 16CA B10B FF04 0001 0003 0283 53

7000 1009 80C1 16CA B10B FF04 0000 0003 0283 73

Example 2

90000099D04OO0099

COM

CALL CONNECTED

9000 000C 18E3 1176 A209 FF04 0080 0003 4003 7F

9000 000C 18E4 1176 A209 FF04 0081 0003 4003 73

9000 000C 18E4 1176 A209 FF04 0080 0009 4003 0000 1000 FBC7 00

9000 000C 18E4 1176 A209 FF04 0081 0009 4203 0002 1000 FB07 99

9000 000C 18E4 1176 A209 FF04 0080 0004 4203 0102

9000 000C 18E4 1176 A209 FF04 0080 0021 4003 0202 1004 0B2B 1932 0145 9990 5008

02AA 4207 0743 0203 0100 0000 3030 4747 4D

9000 000C 18E5 1176 A209 FF04 0081 0004 4003 0104

9000 000C 18E6 1176 A209 FF04 0081 0021 4203 0204 1001 0BB2 9919 3201 4590 5008

02AA 4208 0843 0202 0100 0000 3030 4747 4D

9000 000C 18E6 1176 A209 FF04 0080 0004 4203 0104

9000 000C 18E6 1176 A209 FF04 0080 0011 4003 0404 1001 0F00 0802 AA42 0707 4302

02

9000 000C 18E6 1176 A209 FF04 0081 0004 4003 0106

9000 000C 18E7 1176 A209 FF04 0081 0011 4203 0406 1004 0F00 0802 AA43 0203 4207

07

9000 000C 18E7 1176 A209 FF04 0080 0004 4203 0106

9000 000C 18ED 1176 A209 FF04 0081 0008 FEFF 030F 0000 04FF

9000 000C 18ED 1176 A209 FF04 0080 0009 FCFF 030F 0ABD 0586 03

9000 000C 194B 1176 A209 FF04 0081 0004 4203 0107

9000 000C 194B 1176 A209 FF04 0080 0004 4203 0107

9000 000C 1993 1176 A209 FF04 0080 0009 4003 0606 1004 1300 80

9000 000C 1993 1176 A209 FF04 0081 0004 4003 0108

9000 000C 1994 1176 A209 FF04 0081 0007 4203 0608 1004 17

9000 000C 1994 1176 A209 FF04 0080 0004 4203 0108

9000 000C 1994 1176 A209 FF04 0081 0009 4203 0808 1001 1300 80

9000 000C 1994 1176 A209 FF04 0080 0004 4203 010A

9000 000C 1994 1176 A209 FF04 0080 0007 4003 080A 1001 17

9000 000C 1994 1176 A209 FF04 0081 0004 4003 010A

9000 000C 19F8 1176 A209 FF04 0081 0004 4203 010B

9000 000C 19F8 1176 A209 FF04 0080 0004 4203 010B

9000 000C 1A28 1176 A209 FF04 0080 0003 4003 53

9000 000C 1A29 1176 A209 FF04 0081 0003 4003 73

Outstanding event

Family 12.

Line level from event 00 to 0E: 02 S0 is activated; 03 is deactivated; 00 S0 in service; 01 S0 out of order.

LAP-D from event 30 to 4F: 4E to indicate S0 is within a bundle.

Command management 90 to B2: B0 a B-channel is disconnected; B1 a B-channel is connected (locally initiated); B2 a B-channel is connected (remote request).

D-protocol 60 and an appendix D (within the configuration manual)

Front panel

The status of an S0 interface in terminal mode (TE) is numbered from F1 up to F8, it concerns the D-channel.

These states are coded in BCD (binary coded decimal) on the Led 105(1), 106(2), 107(4), 108(8).

They have the following meanings:

F1: inactive; no connection to network.

F2: detection of the energy source.

F3: inactivation; following detection.

F4: waiting for a signal.

F5: input identification.

F6: synchronization.

F7: activation; data transfer state.

F8: frame locking lost.

For the B-channels, it is like for X.25.

Synchronous PSTN/X.32

General description

The FastPad can be connected to a packet switching network and to a circuit switching network. There are three connection possibilities:

EBS: Synchronous Standardized Input. An X.25 subscriber is connected across the switching circuit network to the FastPad. Only incoming X.25 calls are accepted. The modem operates in automatic answering mode.


Figure 6-80:
Modem Operation
Figure 6-81:
Modem Operation

Conversion of the numeration between the FastPad and the PSTN is necessary.

These services offer many applications.

Note the following two examples:


Figure 6-82: Access to a Public Packet Switching Network Across Switching


Figure 6-83: Backup on Congestion of a Packet Switching Network

Wth the FastPad three different possibilities are offered on PSTN trunk connections. The purpose of the PSTN function is to provide a back-up solution. This function can be used with others like MLP or DLM. For more details refer to "Backup/Overflow/Dynamic Line Management (DLM)" in Chapter 7.

Profile in class 12 are used for the data transfer phase whereas those in Class 13 define behavior during the command mode period

In command mode, one can choose between V.25 bis and Hayes. An explanation of the configuration will be done with two examples and the command diagrams.

Synchronous PSTN stack 108/2 can also be used to allow remote users using X.25 to enter the network.

Since a PSTN network does not provide the calling address, ITU-T has defined a recommendation called X.32. This is a procedure specially based on XID exchange. This exchange take place before the LAP-B establishment.

This procedure can be handled by the modem itself or by the FastPad.

Another option is to use the facility offered by the address translation. In that case, an X.25 call will be accepted only, and only if the calling address is defined within the translation table. This option is not particular to PSTN but is a way to secure the access to the network especially if X.32 or CUG are not used.

The following 2 cases illustrate how, in a general way, what it is possible to do with the synchronous PSTN and the FastPad.

Diagrams in command mode


Figure 6-84: Example 1: Initialization


Figure 6-85: Example 1: Call setting phase in 108/2


Figure 6-86: Example 3: The calling modem is disconnected


Figure 6-87: Example 4: The called modem is disconnected


Figure 6-88: Example 5: The remote part is a phone


Figure 6-89: Example 6: Remote modem is busy

Management

Note For more details about the management function refer to the management manual.

Outstanding events

The same as for X.25.

Maintenance (V54)

To get line status, use the following syntax: T LSxxS.
xx represents the line number.

It is possible to make the different loop defined within the V54 requirements.

There are: B0 or local interface loop (no control through the DB25)

B2 or remote interface loop (with RIL(140) and TI (142).

B3 or local line loop (with LL(141) and TI(142).

The syntax is: T LSxxBy xx is the line number
y is the loop type.

X.32

Overview

The X.32 ITU-T recommendation is used in a circuit switch network such as PSTN, ISDN to secure access to the private network or system and to identify the calling party.

Interworking between CSPDN and PDN network uses this procedure. A remote user will establish a connection with a PDN subscriber through a PSTN network using X.32.

Principle

The identification procedure is based on the exchange of XID frames, which take place before the establishment of the Data Link Layer. There are:

Request and Reply XID frames.
X.32 and Teletex XID format.

See section XID Frame format

Behavior

The behavior during the identification phase is for:

The calling part, like for a DTE.

The called part, like for a DCE.

The level one Identification Procedure is executed when the Data Link Layer is in Disconnect Mode, as follows:


Figure 6-90:
Level One Identification Procedure When Data Link Layer in Disconnect Mode

When the DIAG is positive, the Data Link Layer establishment starts-up, otherwise the physical PSTN connection is disconnected.

When the Data Link Layer is up any incoming XID frame is ignored.

The XID reply to the XID DIAG is optional and the calling party can directly answer with a SABM frame.

When there is no answer to a transmitted XID frame, the time-out and retransmission of LAP(N2*T1) is used. After N2 retries the physical PSTN connection is disconnected.

FastPad and the Identification procedure

Fastpad allows Both XID frame formats (X.32 and Teletex).

As a calling party, it always answers with a XID reply to a XID DIAG.

As a called party, it answers with a positive DIAG and accepts a XID reply or SABM as acknowledgment.


Figure 6-91: XID Frame Format

Back-up with modem in 108/2

There will be a mapping table as for ISDN. In this case, both sites can initiate and accept a call (See Figure 6-92)

The SVC function can also to be used if the PSTN line does not belong to a bundle (see "Backup/Overflow/Dynamic Line Management (DLM)" in Chapter 7 and that user wants to have a transparent back-up solution without loosing the current session.


Figure 6-92: Example

When the leased line (LL) fails, the PSTN backup line is established from mp 900010, when receiving a call request packet for a destination on mp 900020. A dialing command is automatically sent to the modem (Hayes or V.25bis command). Only one side is configured to initiate the backup.

If the Dynamic Line Management (DLM) feature is configured, the PSTN line is automatically disconnected when the leased line is restored.

If the Multi-Link Protocol (MLP) is used in conjunction with the DLM function, the virtual circuits are not cleared during the backup/restore time.

An initialization string must be defined in Class 20 Rec 0. The parameter 9 in the connection profile is an index which specifies which string to use.

ConfigurationTable 6-40 shows the configuration of the above example.


Table 6-40:

900010

9

00020

CLASS 1 RECURRENCE 1

0 1 X.25

3 1 X.25

3 1 X.25

0 1 X.25

CLASS 12 RECURRENCE 0

0 4 X.25

0 5 X.25

CLASS 12 RECURRENCE 3

0 40 X.25

0 41 X.25

CLASS 13 RECURRENCE 3

0 40 X.25

Default values (V10.1)

1 1 V.25bis asynchronous modem

2 2 108/2 call mode (addressed mode)

3 180 Supervision timer (x 1 sec)

4 10 Inactivity timer (x 10 sec)

5 10 Modem data rate in command mode

6 3 Call retry timer (x 1 sec)

7 3 Call retries

8 2 Outgoing call

9 1 Row of modem initialization string in class 20

10 0 XID frame on transmission

11 0 XID frame on reception

12 1

13 1

0 40 X.25

Default values (V10.1)

1 1 V25bis asynchronous modem

2 2 108/2 call mode (addressed mode)

3 180 Supervision timer (x 1 sec)

4 10 Inactivity timer (x 10 sec)

5 10 Modem data rate in command mode

6 3 Call retry timer (x 1 sec)

7 3 Call retries

8 1 Incoming call

9 1 Row of modem initialization string in class 20

10 0 XID frame on transmission

11 0 XID frame on reception

12 1

13 1

CLASS 20 RECURRENCE 0

0 AAAAT Modem initialization string

0 AAAAT Modem initialization string

CLASS 22 RECURRENCE 0

0 900020 X25 remote address

Not used on called side

CLASS 22 RECURRENCE 1

0 7070 PSTN remote number

Not used on called side

CLASS 22 RECURRENCE 2

0 30,00,00 Backup behavior (PSTN outgoing call)

Not used on called side

CLASS 9 RECURRENCE 2

0 20 Known ZO number

0 10 Known ZO number

CLASS 9 RECURRENCE 3

0 4,2,0,0,3 Routing for ZO number 20

0 4,2,0,0,3 Routing for ZO number 10

Configuration

Back-up with modem in 108/1

In this mode, the modem is in charge of dialling over PSTN. The number is stored inside the modem.

In this case, mp's ports do not accept an incoming call.

This mode can be used for hierarchical and security aspects in the network.

The following example (Figure 6-93) illustrates this case.


Figure 6-93:
Example

When the leased line (LL) fails, the PSTN backup line is established from the mp 900010, when receiving a call request packet for a destination on the mp 900020. When the mp raises the DTR control signal, the modem automatically dials a stored PSTN number (Nº 7070 in this example). Only one side is configured to initiate the backup.

When using the 108/1 call procedure, no parameter is configured in class 22. No X.121 addresss is mapped to a particular PSTN number. The 108/1 call procedure cannot be configured to accept incoming call (Parameter 8 in class 13). Therefore, the 108/2 call procedure is configured on the called side.

If the Dynamic Line Management (DLM) feature is configured, the PSTN line is automatically disconnected when the leased line is restored.

If the Multi-Link Protocol (MLP) is used in conjunction with the DLM function, the virtual circuits are not cleared during the backup/restore time.

Table 6-41 shows the configuration.


Table 6-41:

900010

900020

CLASS 1 RECURRENCE 1

0 1 X.25

3 1 X.25

0 1 X.25

3 1 X.25

CLASS 12 RECURRENCE 0

0 4 X.25

0 5 X.25

CLASS 12 RECURRENCE 3

0 40 X.25

0 41 X.25

CLASS 13 RECURRENCE 3

Default values (V10.1)

1 1 V25bis asynchronous modem

2 2 108/2 call mode (addressed mode)

3 180 Supervision timer (x 1 sec)

4 10 Inactivity timer (x 10 sec)

5 10 Modem data rate in command mode

6 3 Call retry timer (x 1 sec)

7 3 Call retries

8 2 Outgoing call

9 1 Row of modem initialization string in class 20

10 0 XID frame on transmission

11 0 XID frame on reception

12 1

13 1

0 41 X.25

Default values (V10.1)

1 1 V25bis asynchronous modem

2 2 108/2 call mode (addressed mode)

3 180 Supervision timer (x 1 sec)

4 10 Inactivity timer (x 10 sec)

5 10 Modem data rate in command mode

6 3 Call retry timer (x 1 sec)

7 3 Call retries

8 1 Incoming call

9 1 Row in c 20

10 0 XID frame on transmission

11 0 XID frame on reception

12 1

13 1

CLASS 20 RECURRENCE 0

0 AAAAAAAAAT Modem initialization string

0 AAAAAAAAAT Modem initialization string

CLASS 9 RECURRENCE 2

0 20 Known ZO number

0 10 Known ZO number

CLASS 9 RECURRENCE 3

0 4,2,0,0,3 Routing for ZO number 20

0 4,2,0,0,3 Routing for ZO number 10

Configuration

Overview Configuration

Structure

Class 1 Rec 1

value

1 synchronous

Class 12 Rec x X physical line number

connection profile

40 DTE backup by V.25 bis or Hayes modem
41 DCE backup by V.25 bis or Hayes modem

Class 13 Rec x

extension profile

40 incoming/outgoing call
41 incoming call
42 incoming/outgoing + XID
43 incoming + XID

Class 22 Mapping table & behavior

rec0 X.121 address
rec1 PSTN number
rec2 behavior
is must be : 30,00,00
30 for in & out call
00 for reserved.

Class 20 Rec 0 Initialization string table

Class 201Rec 0-3 XID frame table

Service Parameters

The following concerns the service parameters for the extension profile used in Class 13.

1 1, V25bis 2,hayes

2 1,direct (108/1) 2,addressed mode(108/2)

3 Supervision timer(1-250)*1s Time within which the PSTN connection must be established.

4 Inactivity timer(0-250)*10s, When this timer expires the PSTN is disconnected.

5 Modem rate in Command mode

6 Time-out between each PSTN dial-up attempt.

7 Numbers of dial-up attempts

8 1, incoming call, 2, incoming/outgoing call

9 index in class 20 rec0 for the initialization string.

10 transmit of XID frame. Rec x in C21

11 reception of XID frame

12 number of XID attempts by the remote.

13 reference values for the inactivity timer 0=1s 1=10s

Value assigned to 6 times value assigned to 7 must be less than value assigned to 3.

(6*7)'s values < 3's values.

SDLC

General Description

It is possible to connect equipment of the type SNA to an X.25 network. SNA (System Network Architecture) is a system introduced by IBM.

The FastPad assures the transport of the SDLC protocol (SNA, level 2) in the X.25 network.

The implementation of that transport is in accordance with the one accepted by IBM. This means that a "Logical Link Control" layer (LLC) is used under SDLC to transport the controller information.

There are two LLC protocols available:

That is why it is possible to have, for example, on one side a cluster controller (SNA node, type T2.0 or T2.1) connected in SDLC to a FastPad and on the other side an SDLC host (SNA node, type T4) or X.25-NPSI.

Figure 6-94 shows an example of the standard architecture for this type of network


Figure 6-94: Example of Standard Architecture

To assure the transport of this protocol there are two types of interfaces available in the FastPad:

Interface to the Primary SNA Node

This interface is intended to connect an IBM front-end Host computer (primary SNA node). It is called "SDLC Front-end". It can emulate a multipoint controller connection. The profile available for this type of interface is:

This interface is intended to connect the terminal controllers (Clusters; secondary SNA nodes). It is called "SDLC Remote". Each interface of this type can serve several multipoint controllers.

The profile available for this type of interface is:

Remote Attachment Via an mp's Network

In a configuration using a remote attachment via an mp's private network, the SNA traffic is carried via X.25 Switched Virtual Circuits (see Figure 6-95). Two standard protocols are used over X.25:

Note Since the PSH procedure is rarely used now, this chapter only deals with the QLLC procedure.

Physical Services Header (PSH)

All X.25 data packets carrying SNA traffic contain a two-byte header followed eventually by SNA data. Two types of PSH messages are exchanged:

Control messages : Used for Mode Setting/Resetting procedures. These messages are identified as PS-CONTACT, PS-DISC, PS-XID, PS-TEST.

Data messages : Carry the actual SNA data to be transferred.

Qualified Logical Link Control (QLLC)

X.25 data packets carrying SNA traffic do not contain any particular header. The following control packets are exchanged with the Qualified (Q) bit set: QXID, QSNRM, QUA, QDISC.

They are used for Mode Setting/Resetting procedures.


Figure 6-95: Remote Attachment via an mp's Network


\xfa

SNA to X.25 Adaptation

An X.25 adaptation is provided on SNA PU4 and PU2 nodes for remote attachment. It is therefore possible to connect such types of SNA nodes to X.25 public or private networks. Permanent Virtual Circuits (PVC) or Switched Virtual Circuits (SVC) are used for that purpose.

Note The remote attachment through X.25 requires the NPSI (X.25 NCP Packet Switching Interface) software on the PU4 Communication Controller.

Figure 6-96: X.25 Remote Attachment Configurations


SNA Interconnection Examples

This section describes some configuration examples of SNA remote attachments via an mp's network.

The following case studies are shown:

PU4 - PU2.0 Point-to-Point Connection

Figure 6-97 shows an SDLC remote attachment between PU4 and PU2.0 SNA nodes via a private mp's network.


Figure 6-97: PU4 to PU2.0 Remote SDLC Point-to-Point Connection


Figure 6-98 shows the data link control messages exchanged to set up the Normal Response Mode. After this, the Mode Setting phase exchange of information can take place. An X.25 call is placed by the mp which faces to the PU2.0 when the latter responds to a UA to the initial SNRM poll of the mp. The exchange of the XID-command between PU4 and PU2.0 is optional and may be skipped. The mp is able to respond to the XID-command in case the PU2.0 is not able to do so.


Figure 6-98: PU4-PU2.0 Normal Response Mode Setting Phase on a Point-to-Point Connection


Figure 6-99:
Example
Table 6-42: Configuration

c1,r1 ( type of the link)

c1,r1

1 4

1 4

c12,r1 (service parameters)

c12,r1

0 18 ( primary sdlc profile)

1 1,16 (PU2.0 emulation)

2 28,10 (data rate 9600b/s)

3 46,1 (subsriber number)

4 90,1 (number of cluster)

5 91,1 (Row of the first cluster in c19r0)

default values

P29,3 (frame size = 384 bytes)

P32,50 (T1, no answer timer, time 100ms)

P34,10 (N2, retry counter)

P35,7 (K,frame window)

P41,1 (QLLC protocol)

P62,8 (Tx-packet size=256)

P63,8 (Rx-packet size)

0 17 ( secondary sdlc profile)

1 1,17 (PU4 emulation)

2 28,10 (data rate 9600b/s)

3 46,1 (subsriber number)

4 90,1 (number of cluster)

5 91,1 (Row of the first cluster in c19r0)

default values

P29,3 (frame size = 384 bytes)

P32,50 (T1, no answer timer, time 100ms)

P33,1 (T0,polling timer,time 100ms)

P34,10 (N2, retry counter)

P35,7 (K,frame window)

P37,200 (Polling counter)

P41,1 (QLLC protocol)

P62,8 (Tx-packet size=256)

P63,8 (Rx-packet size)

c19.r0 ( cluster @ table)

c19,r0

0 0,193

0: not used

193: cluster address in dec

1: Row of the X25 remote FastPad @ in c8r0

193: cluster @ in dec

0 1,193

c8,r0

c8,r4

c9,r7

c8,r0

c8,r4

0 90000001

c8,r0

c8,r4

0 90000001

0,1 (call time-out retransmission * 10s)

c9,r7   (routing for unknown DNIC)

c9,r7 (routing for unknown DNIC)

c9,r7

0 1,1,0, <trunk #>

0,1  (call time-out retransmission * 10s)

PU4 - PU2.0 Multipoint Connection

Figure 6-100 shows a SDLC multipoint configuration with three remote PU2.0 nodes. Note that up to 8 cluster controllers may be remotely attached on one mp's line configured for SDLC multipoint operation.


Figure 6-100: PU4 to PU2.0 Remote SDLC Multipoint Connection


Figure 6-101 shows the data link control messages exchanged to set up the Normal Response Mode. Note that the Normal Response Mode is set for each PU2.0. If one of these fails to respond to the SNRM, it remains in Disconnected Mode. Another SNRM command is repeated periodically until the PU2.0 reacts with the UA response. In Figure 6-101 each PU2.0 has a specific data link address (C1, C2, C3). Figure 6-101 shows the timing between two successive polls for the cluster controller C2, before the reception of a QSNRM packet from the host and the adjacent RR polling for cluster controllers C1 and C3.


Figure 6-101: PU4-PU2.0 Normal Response Mode Setting Phase on a Multipoint Connection

PU4 - PU2.1 Point-to-Point Connection

Figure 6-102 shows an SDLC remote attachment between PU4 and PU2.1 SNA nodes via a private mp's network.


Figure 6-102: PU4 to PU2.1 Remote SDLC Point-to-Point Connection


The following illustrates an example of SDLC connection between a PU4 and a PU2.1

The FastPAD is not able to have an adaptation regarding the result of the negotiation between the two PU's. It means that the PU4 must be Primary and the PU2.1 the Secondary (which is the case most of the time).

Figure 6-103 shows the data link control messages exchanged to set up the Normal Response Mode. In Figure 6-103 the PU2.1 cluster controller refuses the SNRM command by answering a DM response. Usually this is the case since the PU2.1 expects a XID command to start-up the data link. In general the first XID command of the PU4 is a report to the PU2.1, followed by 1 or 2 more XID commands before setting up the Normal Response Mode.


Figure 6-103: PU4-PU2.1 Normal Response Mode Setting Phase on a Point-to-Point Connection
Figure 6-104:
Example
Table 6-43: Configuration

c1,r1 ( type of the link)

c1,r1

1 4

1 4

c12,r1 (service parameters)

c12,r1

0 18 ( primary sdlc profile)

1 1,20 (PU2.1 emulation)

2 28,10 (data rate 9600b/s)

3 46,1 (subsriber number)

4 90,1 (number of cluster)

5 91,1 (Row of the first cluster in c19r0)

default values

P29,3 (frame size = 384 bytes)

P32,50 (T1, no answer timer,time 100ms)

P34,10 (N2, retry counter)

P35,7 (K,frame window)

P41,1 (QLLC protocol)

P62,8 (Tx-packet size=256)

P63,8 (Rx-packet size)

0 17 ( secondary sdlc profile)

1 1,21 (PU4 emulation)

2 28,10 (data rate 9600b/s)

3 46,1 (subsriber number)

4 90,1 (number of cluster)

5 91,1 (Row of the first cluster in c19r0)

default values

P29,3 (frame size = 384 bytes)

P32,50 (T1, no answer timer,time 100ms)

P33,1 (T0,polling timer,time 100ms)

P34,10 (N2, retry counter)

P35,7 (K,frame window)

P37,200 (Polling counter)

P41,1 (QLLC protocol)

P62,8 (Tx-packet size=256)

P63,8 (Rx-packet size)

c19.r0 ( cluster @ table)

c19,r0

0 0,193

0: not used

193: cluster address in dec

1: Row of the X25 remote FastPad @ in c8r0

193: cluster @ in dec

0 1,193

c8,r0

c8,r0

0 90000001

c8,r4

c8,r4

0,1 (call time-out retransmission * 10s)

c9,r7 (routing for unknown DNIC)

c9,r7

0 1,1,0,<trunk #>

0 1,1,0,<trunk #>

PU4 - PU4 Connection

SDLC protocol can also be used to connect two SNA PU4 nodes as shown in Figure 6-105. The Normal Response Mode is also used on such a type of connection. The role of Primary and Secondary station is usually negotiated after 2 or more XID frame exchanges.

Note The negotiation of the Primary and Secondary station role is not negotiable between two PU4 interconnected through mps. This role is determined by the subarea number configured on each PU4 node.

Figure 6-105: PU4 to PU4 Remote SDLC Connection


Figure 6-106 shows the Normal Response Mode setting phase between the two PU4 nodes. Two or more XID frames are usually exchanged before the Primary station sends the SNRM command. Frames sent by the Secondary station have the MSB bit of the data link address set to '1'.

Note In Figure 6-106 that the X.25 call is issued by the mp which faces the Secondary Station as soon as the physical level is in service (control signals present on the serial interface). XID frames received from the Primary and Secondary stations are ignored by the mp until the X.25 Switched Virtual Circuit is established.

Figure 6-106: PU4-PU4 Normal Response Mode Setting Phase
Figure 6-107:
Example
Table 6-44: Configuration

c1,r1 ( type of the link)

c1,r1

1 4

1 4

c12,r1 (service parameters)

c12,r1

0 18 ( primary sdlc profile)

1 1,25 (Secondary PU4 emulation)

2 28,10 (data rate 9600b/s)

3 46,1 (subsriber number)

4 90,1 (number of cluster)

5 91,1 (Row of the first cluster in c19r0)

default values

P29,3 (frame size = 384 bytes)

P32,50 (T1, no answer timer,time 100ms)

P34,10 (N2, retry counter)

P35,7 (K,frame window)

P41,1 (QLLC protocol)

P62,8 (Tx-packet size=256)

P63,8 (Rx-packet size)

0 17 ( secondary sdlc profile)

1 1,26 (Primary PU4 emulation)

2 28,10 (data rate 9600b/s)

3 46,1 (subsriber number)

4 90,1 (number of cluster)

5 91,1 (Row of the first cluster in c19r0)

default values

P29,3 (frame size = 384 bytes)

P32,50 (T1, no answer timer,time 100ms)

P33,1 (T0,polling timer,time 100ms)

P34,10 (N2, retry counter)

P35,7 (K,frame window)

P37,200 (Polling counter)

P41,1 (QLLC protocol)

P62,8 (Tx-packet size=256)

P63,8 (Rx-packet size)

c19.r0 ( cluster @ table)

c19,r0

0 0,193

0: not used

193: cluster address in dec

1: Row of the X25 remote FastPad @ in c8r0

193: cluster @ in dec

0 1,193

c8,r0

c8,r0

0 90000001

c8,r4

c8,r4

0,1 (call time-out retransmission * 10s)

c9,r7 (routing for unknown DNIC)

0 1,1,0,<trunk #>

c9,r7 (routing for unknown DNIC)

0 1,1,0,<trunk #>

SDLC PU2.1 - PU2.1

The FastPad does not manage the negotiation for the primary function.

XID Polling timer value must be higher than T0 from the mp.


Figure 6-108:
Example
Table 6-45: Configuration

c1,r1 ( type of the link)

c1,r1

1 4

1 4

c12,r1 (service parameters)

c12,r1

0 18 ( primary sdlc profile)

1 1,22 (Secondary PU2.1 emulation)

2 28,10 (data rate 9600b/s)

3 46,1 (subsriber number)

4 90,1 (number of cluster)

5 91,1 (Row of the first cluster in c19r0)

default values

P29,3 (frame size = 384 bytes)

P32,50 (T1, no answer timer,time 100ms)

P34,10 (N2, retry counter)

P35,7 (K,frame window)

P41,1 (QLLC protocol)

P62,8 (Tx-packet size=256)

P63,8 (Rx-packet size)

0 17 ( secondary sdlc profile)

1 1,23 (Primary PU2.1 emulation)

2 28,10 (data rate 9600b/s)

3 46,1 (subsriber number)

4 90,1 (number of cluster)

5 91,1 (Row of the first cluster in c19r0)

default values

P29,3 (frame size = 384 bytes)

P32,50 (T1, no answer timer,time 100ms)

P33,1 (T0,polling timer,time 100ms)

P34,10 (N2, retry counter)

P35,7 (K,frame window)

P37,200 (Polling counter)

P41,1 (QLLC protocol)

P62,8 (Tx-packet size=256)

P63,8 (Rx-packet size)

c19.r0 ( cluster @ table)

c19,r0

0 0,193

0: not used

193: cluster address in dec

1: Row of the X25 remote FastPad @ in c8r0

193: cluster @ in dec

0 1,193

c8,r0

c8,r0

0 90000001

c8,r4

c8,r4

0,1 (call time-out retransmission * 10s)

c9,r7 (routing for unknown DNIC)

0 1,1,0,<trunk #>

c9,r7 (routing for unknown DNIC)

0 1,1,0,<trunk #>

PU4/NPSI (using PVC) - PU2.0 in SDLC


Figure 6-109:
Example
Table 6-46: PU4/NPSI (using PVC) - PU2.0 in SDLC

c1,r1 ( type of the link)

c1,r1

1 1 X.25

1 4

c12,r1 (service parameters)

c12,r1

0 1 (X.25 user line(DCE))

1 2,0 ( Standard X.25)

2 5,2 (1st incoming)

3 9,2 (1st bothways)

4 11,0 (Nbr of bothways)

5 13,2 (1st outgoing)

6 28,10 (data rate 9600b/s)

7 32,30 (T1 = 3s)

8 33,10 (T2 = 1s)

9 35,7 (K = 7)

10 45,2 (mode 2 addresses)

11 48,0 (no CUG)

12 56,0 (no Throughput neg)

13 90,1 (Nbr of PVC)

14 91,1 (1st entry in C17R0)

default values

P29,2 (frame size = 256 bytes)

P34,10 (N2, retry counter)

P62,7 (Tx-packet size=128)

P63,7 (Rx-packet size=128)

P69,2 (Tx-window size)

P70,2 (Rx-Window size)

0 17 ( secondary sdlc profile)

1 1,19 (PU4 emulation)

2 28,10 (data rate 9600b/s)

3 46,1 (subsriber number)

4 90,1 (number of cluster)

5 91,1 (Row of the first cluster in c19r0)

default values

P29,3 (frame size = 384 bytes)

P32,50 (T1, no answer timer,time 100ms)

P33,1 (T0,polling timer,time 100ms)

P34,10 (N2, retry counter)

P35,7 (K,frame window)

P37,200 (Polling counter)

P41,1 (QLLC protocol)

P62,8 (Tx-packet size=256)

P63,8 (Rx-packet size)

c17r0

c19,r0

0 0,1,1,1

0: not used

1 called side

1 local Lcn

1:remote Lcn

0 1,193

1: Row of the X25 remote FastPad @ in c8r0

c8,r0

193: cluster @ in dec

c8,r0

0 90000001

c8,r4

0,1 (call time-out retransmission * 10s

c9,r7

0 1,1,0,<trunk #>

PU4/NPSI(using SVC) - PU2.0 in SDLC


Figure 6-110:
Example

TCU @ = C1hex


Table 6-47: Configuration

c1,r1 ( type of the link)

c1,r1

1 1 X.25

1 4

c12,r1 (service parameters)

c12,r1

0 1 (X.25 user line(DCE))

1 2,0 ( Standard X.25)

2 5,11 (1st incoming)

3 9,1 (1st bothways)

4 11,10 (Nbr of bothways)

5 13,1 (1st outgoing)

6 28,10 (data rate 9600b/s)

7 32,30 (T1 = 3s)

8 33,10 (T2 = 1s)

9 35,7 (K = 7)

10 45,2 (mode 2 addresses)

11 48,0 (no CUG)

12 56,0 (no Throughput neg)

default values

P29,2 (frame size = 256 bytes)

P34,10 (N2, retry counter)

P62,7 (Tx-packet size=128)

P63,7 (Rx-packet size=128)

P69,2 (Tx-window size)

P70,2 (Rx-Window size)

0 17 ( secondary sdlc profile)

1 1,19 (PU4 emulation)

2 28,10 (data rate 9600b/s)

3 46,1 (subsriber number)

4 90,1 (number of cluster)

5 91,1 (Row of the first cluster in c19r0)

default values

P29,3 (frame size = 384 bytes)

P32,50 (T1, no answer timer,time 100ms)

P33,1 (T0,polling timer,time 100ms)

P34,10 (N2, retry counter)

P35,7 (K,frame window)

P37,200 (Polling counter)

P41,1 (QLLC protocol)

P62,8 (Tx-packet size=256)

P63,8 (Rx-packet size)

c19,r0

0 1,193

1: Row of the X25 remote FastPad @ in c8r0

193: cluster @ in dec

c8,r0

0 90000001

c8,r4

0,1 (call time-out retransmission * 10s)

c9,r7

0 1,1,0,<trunk #>

Work Sheet

Project name: ..........................................................................................................

Customer @: ...........................................................................................................

Contact points: ........................................................................................................

Date: .......................................................................................................................

Objective:................................................................................................................

Diagram:.................................................................................................................

Node address:..........................................................................................................

Port number:............................................................................................................


Figure 6-111: Example
Table 6-48:

1r1: type of line

C1r1: type of line

port#>: 4 (sdlc type)

port#>: 4 (sdlc type)

12r<port#>:

service parameter

C12r<port#>:

service parameter

profile 18 for Primary sdlc

profile 17 for Primary sdlc

P1 PU's type

16 PU4

PU2.0

18 PU4

PU2/NPSI

P1 PU's type

17 PU4

PU4

19 PU2.0,2.1

PU4/NPSI

20 PU4

PU2.1

22 PU2.1

PU2.1

21 PU2.1

PU4.1

22 PU2.1

PU2.1

25 PU4

PU4

24 PU2.1

PU2.1 1/NPSI

25 PU4

PU4

P16 Encoding type:

0 NRZ     0 NRZI

P16 Encoding type:

0 NRZ     0 NRZI

P29 Frame size:

P29 Frame size:

P32T1 (no answer time):

in steps of 100ms

P32T1 (no answer time):

in steps of 100ms

P34 N2 (retry number):

P33TO (polling interval)

n steps of 100ms

P35 K frame windows):

P34 N2 (retry number):

P40 PSH segment:

P35 K frame windows):

P41 Procedure type:

0 PSH        1 QLLC

P40 PSH segment:

P42 (# of calls transmitted):

P41 Procedure type:

0 PSH        1 QLLC

P46 Subscriber number:

P42 (# of calls transmitted):

P62 Default packet size:

P46 Subscriber number:

P90 Number of cluster:

P62, P63 Default packet size:

P91 Row R of the first cluster in C19r0:

P90 Number of cluster:

P40 PSH Encoding type:

P91 Row R of the first cluster in C19r0:

P41 Encoding type:

19r0:

Cluster @ table

C19r0:

Cluster @ table

R-1>:0<cluster @ in Dec>

<R-1:0>cluster @ in Dec>

P41 Encoding type:

C8r0:

X25 remote FastPAD address

<Q-1>:

X25 address, X

C8r4:

Retransmission time-out

<Q-1>:

in steps on 10 s

C8r2:

Xld transmission if need be

<Q-1>:

Configuration
Note The routing information is not present here since its principle is the same for all the protocols.

SDLC Frame Structure

In SDLC, data between two Logical Stations is transmitted in the form of "frames". All information sent via the data link, including real data and control information, is put in a frame. A frame comprises the following fields (see Figure 6-102):


Figure 6-112: SDLC Frame Structure

Description of SDLC Commands and Responses

The different SDLC frame types are cataloged in three groups. These three groups apply to commands as well as to responses. These three groups are:

An overview of the possible commands and responses is given in Table 6-49.


Table 6-49: SDLC Commands and Responses on Multipoint and Point-to-Point Configurations

CATEGORY

COMMANDS
3

RESPONSES
3

CONTROL FIELD

HEX VALUE

7

6

5

4

3

2

1

0

P/F = 1

P/F = 0

I-FRAME

I

r

r

r

PF

s

s

s

0

even

even

S-FRAME

RR

RR

r

r

r

P/F

0

0

0

1

x1 1

x2 1

RNR

RNR

r

r

r

P/F

0

1

0

1

x1 5

x2 5

REJ

REJ

r

r

r

P/F

1

0

0

1

x1 9

x2 9

U-FRAME

SNRM

1

0

0

P

0

0

1

1

93

83

SNRME

1

1

0

P

1

1

1

1

DF

CF

DM

0

0

0

P/F

1

1

1

1

1F

0F

DISC

RD

0

1

0

P/F

O

O

1

1

53

43

UA

0

1

1

P

O

O

1

1

73

63

SIM

RIM

0

0

0

P/F

O

1

1

1

17

07

TEST

TEST

1

1

1

P/F

O

O

1

1

F3

E3

XID

XID

1

0

1

P/F

1

1

1

1

BF

AF

UI

UI

0

0

0

P/F

O

O

1

1

13

03

FRMR

1

0

0

F

O

O

1

1

97

87

r = receive counter 1 odd number
s = send counter 2 even number
P = poll bit
F = final bit

BSC 3270

General description

Equipment of the type BSC 3270 can be connected to the FastPad. Configuration of BSC is governed by the software license (BSC).

The FastPad assures the local emulation of the character synchronous BSC 3270 procedure (BSC = Binary Synchronous Communication) and the transport of the data messages.

The FastPad network is transparent to the multipoint BSC link. Figure 6-113 gives the standard architecture for this type of network.


Figure 6-113: BSC 3270 Connection in a Network

TCU

=

Terminal Controller Unit.

Station

=

Terminal (screen or printer)

To assure the data transport of this protocol, a virtual circuit is established between the two types of interface available on the FastPad equipment:

Host Interface

The interface, connecting the host interfaces, is called HPAD.

It emulates a multipoint connection of the controllers.

The available profile for this type of interface is:

TCU Interface

This interface, connecting the terminal controllers, is called TPAD. Each interface of this type supports several controllers in a multipoint connection.

The available profile for this interface type is:

Profile 60 in class 12: BSC controller (TPAD).

The address list for the terminals present on the BSC line must thus be configured in C13 profile 60 (predefined station address list).

Each terminal controller that wants to connect to a host, must know the X.25 address of the corresponding HPAD interface, to be able to establish a virtual circuit for each station or for each controller.

For this reason, the user must configure the controller address table in class 19 and the automatic calling table in class 8.

BSC 3270 Parameter:


Table 6-50: BSC 3270 Parameter

HPAD

TPAD

Profile 61

Profile 60

28

Access rate

28

Access rate

32

No host polling timer

33

polling ? timer

36

type of coding

34

type of coding

39

WACK transmission

if start print bit in WCC is turned on

36

WACK transmission

if start print bit in WCC is turned on

40

ACK reply if no SVC

41

no reply timer

41

no reply timer

42

retry, reenter

42

retry, reenter

62

block length

62

block length

46

subscriber no.

46

subscriber no.

37

parity

37

parity

35

ingress queue depth

35

ingress queue depth

90

number of cluster

90

number of cluster

91

entry index in C19R0

91

entry index in C19R0

Remark:

Maximum number of clusters per port is 32.

Maximum number of stations per port is 32.

*(1) start print bit

(2) WCC write control character

(3) RVI reverse interrupt

(4) ITB Intere transmission block


Figure 6-114: Configuration example
Table 6-51:

C1, R1

C1, R1

Par. 1 : 8 (line type = BSC)

Par. 1 : 8 (line type = BSC)

C12, R1

C12, R1

Profile : 61

Par. 28 : 6 (Data rate 2400 bit/s)

Par. 32 : 6 (Host polling time out)

Par. 40: 1 (Answer to poll/select only if VC exist)

Par. 90 : 1 (Co. of cluster controllers)

Par. 91 : 1 (Row of first cluster)

Default values

Par. 29 : 5 (BSC clock sie = 640 bytes)

Par. 32 : 3 (Host polling time out)

Par. 36 : 0 (EBCDIC code)

Par. 62 : 10 (Tx packet size = 1024 bytes)

Par. 63 : 7 (Rx packet size = 128 bytes, don't change)

Profile : 60

Par. 28 : 6 (Data rate 2400 bit/s)

Par. 33 : 6 (mp polling interval)

Par. 46: 1 (Answer to poll/select only if VC exist)

Par. 90 : 1 (Co. of cluster controllers)

Par. 91 : 1 (Row of first cluster)

Default values

Par. 29 : 5 (BSC clock sie = 640 bytes)

Par. 33 : 3 (mp polling interval)

Par. 36 : 0 (EBCDIC code)

Par. 62 : 10 (Tx packet size = 1024 bytes)

Par. 63 : 7 (Rx packet size = 128 bytes, don't change)

C13, R1

C13, R1

Profile : 60

Profile : 60

C19, R0

C19, R0

Par. 0 : 0 , 0 , 1 , 1

0 = Not used
0 = Cluster address (=40)
1 = Number of stations for this cluster
1 = First station indexin C13 (=40)

Par. 0 : 0 , 0 , 1 , 1

0 = Row of automatic call in class 8
0 = Cluster address (=40)(*)
1 = Number of stations for this cluster
1 = First station indexin C13 (=40)(*)

C8, R0

C8, R0

---

Par. 0 : 9000 00 01 (Called address)

C8, R4

C8, R4

---

Par. 0 : 1 (Called time-out retransmission)

C9, R2

C9, R2

Par. i : 10 (zone number)

Par. i' : 00 (Zone number)

C9, R3

C9, R3

Par. j : 1 , 1 , 0 , 0 (Routing for zone 10)

Par. i' : 1 , 1 , 0 , 0 (Routing for zone 00)

C9, R4

C9, R4

Par. i : 01 (Subscriber number)

Par. i' : 01 (Subscriber number)

C9, R5

C9, R5

Par. i : 1 , 1 , 0 , 1 (Routing for subscriber 01)

Par. i : 1 , 1 , 0 , 1 (Routing for subscriber 01)

Configuration

(*) Table in Chapter 9 "Extension Profile and Parameters" for complete survey of addresses.

BSC 2780/3780

General description

Equipment of the type BSC 2780/3780 can be connected to the FastPad.

The FastPad assures the local emulation of the character synchronous BSC 2780/3780 procedure (BSC = Binary Synchronous Communication) and the transport of the data messages.

The FastPad network is transparent to the multipoint BSC link.

Figure 6-116 gives the standard architecture for this type of network.


Figure 6-115: Case (1)
Figure 6-116: Standard Architecture

PSTN = Public Switched Telephone Network

CPU = Control Processor Unit

To assure the data transport of this protocol, a virtual circuit is established between the two types of interface, available on the FastPad equipment:

"Calling" interface

This interface connects the BSC 2780/3780 equipment that requests a transfer. With BSC 3780, it is possible to emulate several terminals via the PSTN; in that case the identification of the terminal must be managed.

The available profiles for these types of interfaces are:

"Called" interface

This interface is used to connect the BSC 2780/3780 equipment that receives the transfer request. The identification of the terminal must be managed when the "calling" side connects several BSC 3780 terminals via the PSTN.

The available profiles are:

To enable the establishment of a virtual channel, it is necessary for the BSC 2780/3780 "calling as well as "called" side to know the X.25 address of the corresponding interface.

For that reason, the user must configure this in the "automatic calling table" (classes 8 and 19) and if the terminal identification must also be managed, they must be configured in class 13, profile 70.

Configuration of a BSC 2780/3780 Line

The following diagram gives the steps in the configuration process of an SSC 2780/3780 line, using the standard profiles.

Additional parameters can be configured according to specific needs of the user.

Details of the parameters are described in Chapter 4.


Figure 6-117:
Configuration of a BSC 2780/3780 Line
Figure 6-118: Configuration of a BSC 2780/3780 Line (Con't.)

Transparent BSC

General Description

The transparent BSC (BSC-T) function is used to connect most variants of the BSC protocol through an X.25 network.

The chosen principle consists of detecting frames on the physical connection, packetizing them, directing them to an X.25 network, and transmitting them as they are to the remote BSC-T connection.

No local emulation of the BSC protocol takes place; hence there is no sensitivity to procedure variations and only the format of the frame must be recognized.

Similarly, cyclic redundancy is not checked, and is carried without transformation in order to optimize the processing time in the concentrator.

What remains then is to ensure the possibility of recognizing the frame formats of the varying BSC standard protocol. This is achieved by the configuration of class 13 which, within the limits of the adapted structure, enables the recognition of most BSC type frames.

The configuration of this class is of primary importance for frame recognition, as configuration errors could lead to non-recognition of certain frames or erroneous interpretations of frames resulting in truncated frames.

Profiles exist; their suitability for the connected protocol must simply be ascertained.

It is possible to depart from the values given in the profiles. It is recommended that the validity at a profile of a modification for a given case should be checked out with the Cisco user support department.

In any case, responsibility for the selection of profiles, or modifications in relation to profiles falls on the person making the configuration choices.


Figure 6-119:
BSC-T Connection in a Network

Configuration of BSC-T connections

Two parts may be distinguished in the configuration of BSC-T connections:

These configurations follow the plan given in the block diagram below.

It is possible to modify the parameters of the connection given by the profiles, in Class 12 and 13.

Details about the parameters of Classes 12 and 13 are given in Chapter 4.


Figure 6-120: Configuration of a BSC-T Connection
Figure 6-121: Configuration of a BSC-T Connection (Con't.)


Figure 6-122:
Line x BSC- T Connection
Table 6-52:

Main Frame Side:

DNIC Z0

: 200030

C17, R0 P.V.C or LLP tables, 250P

Port 01

0 1, 1, 0, 1

C1 Configuration identification

C8 automatic call numbers

C1, R1 type of lines, 42P

C8, R0 called address (16 char.), 200P

0 14401002

C8, R4 CALL retrans. time-out (200P),

0 1

1

7

C12 connection: synchronous parameters

C12, R1 connection param. of line 2, 41P

0

1

2

3

5

6

11

12

13

14

15

16

17

102

91,1

29, 16

28, 10

1, 2

33, 0

92, 0

20, 0

21, 1

24, 0

25, 1

26, 5

46, 1

Reserved (profile)

Position if connection (C17)

NB of buffers/frame

Interface clock rate

Type of link

Additional syns.

One pad suppression

I/O Interface status def.

I/O Interface status def.

Interface sign rec.

Interface sign rec.

Interface sign trans.

No. of calling subscribe

* 1 to 250

* 1 = DTE, 2 = DCE

* 0 or 2

* 0 = No, 1 = yes

* 8 = 105

* 8 = 105

* states defined

* states defined

*

*

C13 connection: extension parameters

C13, R1

extens. param. of line 2, 22/32P

0

100 Reserved (profile)

C17 P.V.C. or DLCI tables

Remote Side:

DNIC Z0

: 144010

C17, R0 P.V.C or LLP tables, 250P

Port 02

0 1, 1, 0, 1

C1 Configuration identification

C8 automatic call numbers

C1, R1 type of lines, 42P

2

7

C12 connection: synchronous parameters

C12, R2 connection param. of line 2, 41P

0

102

Reserved (profile)

1

91,1

Position if connection (C17)

* 1 to 250

2

29, 16

NB of buffers/frame

* 1 = 128 * 1 to 256

3

28, 10

Interface clock rate

* 6 = 2400 8 = 4800

5

1, 2

Type of link

* 1 = DTE, 2 = DCE

6

33, 0

Additional syns.

* 0 or 2

7

62, 11

Def. pkt. size on trans.

* 5 = 32, 6 = 64

11

92, 0

One pad suppression

* 0 = No, 1 = yes

12

20, 0

I/O Interface status def.

* 8 = 105

13

21, 1

I/O Interface status def.

* 1 = 111, 2 = 140

14

24, 0

Interface sign rec.

* states defined

15

25, 1

Interface sign rec.

* states defined

16

26, 5

Interface sign trans.

*

17

46, 2

No. of calling subscribe

*

C13 connection: extension parameters

C13, R2

extens. param. of line 2, 22/32P

0

100 Reserved (profile)

C17 PVC or DLCI tables

C17, R0 PVC or LLP tables, 250P

0

1, 0, 0, 2

C8 automatic call numbers

C8, R0

called addresses (16 char.), 200P

0

20003001

C8, R4

CALL retrans. time-out, 200P

0

1

Configuration

VIP

Overview


Table 6-53: Table

OSI

BULL

7

application

6

DSA

5

4

3

2

VIP

1

1

Figure 6-123 illustrates the different components of a DSA Network.


Figure 6-123: Different Components of a DDSA Network

TERMINOLOGY:

DSA: Distributed System Architecture.

Host: Main-frame such as Min6, DPS6000/7000.

Datanet: Front-end processor providing concentration and switching function.

TCU: Terminal Control Unit such as Questar F/T, Questar 1410/1420 ATM.

DKU: Display Keyboard Unit.

Station: DKU or DKU + printer.

VIP SPECIFICATIONS:

Allows point-to-point and multipoint connections.

The data link procedure is Half-Duplex.

The coding type is ASCII 7bits plus ODD parity.

The checksum use the LRC method.

VIP is Character Oriented Protocol (COP) such as BSC from IBM.

Synchronization is done on SYN character.

FASTPAD and VIP:

Figure 6-124 illustrates a standard set-up.


Figure 6-124: Standard Set-up for VIP and FastPAD


The FastPads locally emulate VIP protocol and does spoofing.

The port connected to the front-end processor is called HPAD.

The port connected to the remote side is called a TPAD.

Since there is spoofing, the network is transparent for the end devices. Only text messages pass through the network.

Physical Connection Type:

Direct lines, dedicated lines, PSTN (Datanet calls the HPAD, TCU calls the TPAD)

The Logical Link is done from the TPAD to the HPAD. As soon as the station answers to the polling, the TPAD will send the call request using automatic calling behavior.

VIP PARAMETERS:

HPAD

TPAD

51

connection profile number

50

connection profile number

29

frame size

29

frame size

32

interpolling timer

32

no reply polling timer

33

delay for ack printer

33

inter cycle polling timer

35

ingress queue depth

34

no reply polling counter

37

No EOT if NO cv

35

ingress queue depth

39

no reply screen messg timer

39

no reply screenmessg timer

40

no reply printer messg timer

40

no reply printer messg timer

42

retry counter for messg

42

retry counter for messg

43

local mgmt of printer messg

43

local mgmt of printer messg

62

message length

62

message length

90

number of polled addresses

90

number of polled addresses

91

1st entry in c19r0

91

1st entry in c19r0

Note for the HPAD:

If parameter 43 is turned on, then 33 is not significant. Value of parameter 32 needs to be greater than or equal to the polling timer of the host. The Ingress queue value needs to be greater than or equal to the message length send by the TCU.

For the TPAD

The ingress queue value needs to be greater than or at least equal to message length sent by the HPAD.

The extension profile number to use in Class 13 <port #> is : Profile 50

A maximum of 8 clusters per TPAD line

A Maximum of 32 stations per TPAD line.

Ex: a TCU with 8 stations each
1 TCU with 32 stations

Cluster/Station addresses are defined in C19R0.

C19R0

For each entry there are four fields (A,B,C,D)

row

x A,B,C,D

A: entry in C8 for the X.121 @ of the Hpad.

B: TCU @ or Station @ if polling station

C: number of stations attached behind the TCU. If 0, it means polling station.

D: Entry in C13.

The extension profile 50 used in C13Rx and contents VIP addresses.

Configuration example:


Figure 6-125: Example


Access rate on HPAD is 19,2kb/s and 9,6kb/s on TPAD. TCU 1 behind the TPAD has three stations (addresses:1,2,3).TCU 3 behind the TPAD has 3 stations (addresses:5,6,27). There is a polling station for the address 27. Local management for printer is turned on. The HPAD does not answer to the host polling if there is no SVC. No reply polling timer (TPAD) is 1s. Message length up to 4Kb.


Table 6-54: Configuration

C1 R1

1 6 VIP

1 6 VIP

C12 R1

0 51 VIP connection profile HPAD

0 50 VIP connection profile TPAD

1 28,11 19,2kb/s

2 29,32 for 4KB message

3 35,40 Ingress queue depth

4 37,0 No EOT answer if no SVC

5 43,1 Local mngt t for PRN messg

6 46,1 Subscriber number

7 62,12 messg length up to 4KB

8 90,3 Tree polling addresses

9 91,1 First entry in C19R0

1 28,10 9,6kb/s

2 29,32 for 4KB message

3 32,10 no reply polling timer

4 35,40 Ingress queue depth

5 43,1 Local mngt for PRN messg

6 46,1 Subscriber number

7 62,12 messg length up to 4KB

8 90,3 Tree poling addresses

9 91,1 First entry in C19R0

other default values

32,30 interpolling timer time out

33,30 delay for ack printer

39,1 no reply screen messg timer

40,7 no reply printer messg counter

42,5 retry counter for messg

33,3 inter cycle polling timer

34,6 no reply polling counter

36,0 polling type after a select

41,0 the transmit request is ignored

40,7 no reply printer messg counter

C13 R1

0 50 VIP extension profile

0 50 VIP extension profile

C19 R0

0 1,1,3,2



1 1,3,2,6




2 1,27,0,28

1: First entry in C8

1: TCU 1

3: Tree stations behind TCU 1(polling cluster)

2: 2nd entry in C13R1


1: First entry in C8

3: TCU 3

2: Two stations behind TCU 3(polling cluster)

6: 6th entry in C13R1

1: First entry in C8

27: Station 27

0: Polling station

28: 28th entry in C13R1

0 1,1,3,2



1 1,3,2,6

2 1,27,0,28

C8 R0

0 90000001 TPAD calling address

0 80000001 HPAD remote address

C8 R4

0 0 no slow call

0 1 slow call of 10 s

Asynchronous

OVERVIEW

  Pad devices: such as TTY, HP terminal, SLIP/PPP terminal, LSCP.
  VAP devices: for videotext terminal such as French Minitel, Teletel.
  PAD-M: for multistandard videotext terminal such as VDNX, BTX, Prestel.
  X.28plus: for terminal with Telenet and Sprintnet behavior.

This function is the interface between the Asynchronous device procedure and the X.25 protocol. It meets the following requirements:

X.3 recommendation: specifies a set of 22 PAD parameters that determine how the PAD adapts the Asynchronous DATA stream from the DTE into X.25 packets and vice versa.

X.28 recommendation: describes the DTE/DCE interface between a synchronous DTE and a PAD such as: procedure to establish a call, to exchange data between the asynchronous device and a PAD, to exchange control information.

X.29 recommendation: defines the procedures for exchanging control information between a PAD and a remote PAD.


Figure 6-126: Asynchronous


PHYSICAL CONNECTIONS:

Figure 6-127 gives an overview of the different main connection profiles used.


Figure 6-127: Overview of Different Main Connection Profiles Used


Note For X.3 (C13R<port #>) parameters, refer to the Extension profile and parameters chapter.

C14R0 is used to define a specific customer profile that does not follow X.3
recommendation. (Profile number 80).

PAD

Virtual circuit principle establishment,

Three possibilities are offered to do this.

    1. addressed call:

The X.121 address is indicated by the terminal according to the X.2b recommendations.

* Presentation of a Network User Identifier (NUI)

Nxxxxxx- Called address or mnemonic. The NUI allows up to six characters and is not echoed

Ex: if the user NUI is "naoned" and the remote address is 19681005.

Nnaoned - 19681005

NUI ON/ NUI OFF case:

When the request for the identification of a remote PSTN terminal is configured (C12RxP39,10); the user must enter an NUI ON or NUI OFF command before sending the call.

The NUI ON allows the entry of an identification (up to 15 digits) which become the calling address of the remote terminal and is transported in the corresponding facility field of the Call Request.

The NUI OFF is used to turn on the Reverse Charging facility in the Call Request.

If the user tries to set-up a call without using first these commands the PSTN connection is disconnected.

* Using the Reverse Charging (RC):

Syntax: R-Called address or mnemonic.

* Using the Closed User Group (GUG):

Syntax: Gxx-Called address or mnemonic. Xx is the CUG value.

    2. Abbreviated call:

The user types a mnemonic instead of standard address. The mnemonic is defined

in C7R0,R1,R2,R3.

    3. Automatic call:

When the port goes up the PAD function will send a call which is predefined in

C8R0,R1,R2.

X.28 Procedure

The X.28 procedure determines the commands accessible via an asynchronous terminal intended for the PAD to which it is directly connected. These commands are the following:


Table 6-55: X.28 Commands
Commands Function Response of PAD

STAT

Request for status of virtual call between PAD and terminal

ENGAGED = VC established FREE = VC not established

CLR

Request to clear call

CLR = call cleared

PAR? No. of parameters

Request for value of one or more parameters

EX: PAR? 1, 2, 5

Note: To determine the values of all the parameters, simply type PAR?

Parameters followed by their value

EX: PAR 1: 0.2 : 1.5 : 1

SET? No. of parameters new values, etc.

Modification of value of one or more parameters

EX: SET? 1: 0.2 : 0.4 : 3

Parameters followed by their new value

EX: PAR 1: 0.2 " 0.4 : 3

PROF Profile number

Choice of a standard profiles

RESET

Resetting of a call

INIT

Sending of an interrupt

MSET? No. of parameters

Generation of PAD message for positioning of parameter

None or ERROR if refused by far end

mpAR No. of parameters

Generation of PAD message for positioning of parameter, reading of parameter of far end

Parameters followed by their values

RSET? No. of parameters

Generation of PAD message for positioning of parameter

Non or ERROR if refused by far end

RPAR No. of parameters

Generation of PAD message for positioning of parameter, reading of parameter of far end

Parameter followed by their value
Note Modifications of X.3 parameters by X.28 or X.29 commands are valid only while user is on communication. After the line goes down the X.3 parameters values are those define in C13Rx.

Examples:

Default TTY.

By default port 5 (12 modulo) uses the following configuration.

C1R1

5 2 Asynch type

C12R5 C13R5

0 7 Asynch connection profile 0 89 TTY extension profile

1 27,3 indication.

Profile 7 uses the RAV and RAP. The user must type H carriage return to get the welcome page.

TTY without RAV, RAP and mnemonic.

C1R1

5 2 Asynch type

C12R5 C13R5

0 8 Asynch connection profile 0 89

1 27,3 11 14 9600b/s

C7R0 C7R1 C7R3

0 NY 0 70000099 0 00GG call used data

User A to reach the traffic generator function of node 7000 00 can type;

70000099D00GG or NY

SLIP/PPP

Extension profile 48 for SLIP (Serial Link Internet Protocol).

Extension profile 49 for PPP (Point-to-Point Protocol)

The data forwarding character (X.3P3) is /C0 for SLIP and /7E for PPP. Only the second one of each block is taken into account to forward message.

Note Except X.3P2 and X.3P6 all other X.3 parameters cannot be changed.

Figure 6-128: SLIP/PPP


There is an automatic call to reach the remote router when port 5 goes up.

C1R1

0 2 Asych type

C12R5 C13R5

0 9 Asych connection PSTN profile 0 49 Extension profile for PPP

1 27,3

2 32,10 Inactivity time-out(100s)

3 46,5 Subscriber number

4 38,1 Entry in C8

C8R0

0 X.121 @

C8R4

0 1 Call retransmission time-out *10s

PAD overview configuration


Figure 6-129:
Configuration of an Asynchronous Line

VAP

The Welcome page for the device is defined in C15R0

Error Correction Procedure (ECP)

The error correction procedure is a service offered by the VAP (Videotex Access Point) function. It corrects errors which are introduced by the network (PSTN) on the 1200 bauD-channel of the VAP-terminal (minitel) connection.

There are two types of error corrections. Which one is used depends on the mode of the modem

ECPN is activated (inactivated) on request of:

The ECPI is activated (inactivated) on request of:

The error threshold can be set with a configuration parameter: C12P90

The transmission time-out of a re-transmission request (ECPN) is set with configuration parameter, C12P91.

VAP overview configuration.

C1R1

<port #> 2 asynch type

C12R<port#> C12R<port#>

0 15 direct connection profile 0 35 PSTN (ECP)

16 PSTN connection profile

36 PSTN 75/1200 connection profile

C13R<port#> C13R<port#>

0 30 Videotext 0 46 PSTN videotext

P1 to P22

C6R0,R1 NUI/NUA table

C7R0-R3 mnemonic table

C8R0-R2 Automatic calling table

C12<port #>

P93 type of mnemonic

P90 Threshold error for ecp

P91 Threshold time-out nack for ecp

C15R0,R1 Welcome page

PAD-M

This function is used to connect over PSTN network a multistandard videotext terminal to a server via a gateway (groom).


Figure 6-130: PAD-M


The mp is in charge of determining the identity of the terminal and establishing a logical connection with the groom giving the identity of the terminal.

During communication, the mp is transparent to X.29 indications. However it manages one X.29 message (before the communication takes place). This is the

ID request: TFI, ENQ, TER (seeC12RxP18,P19).

Note The PAD-M uses only automatic call to establish the Logical link with groom.

PAD-M overview configuration.

C1R1:

< port #> 2 Asynch type.

C12R<port #>: C13R<port#>

0 37 Multistandard connection profile 0 32 Pad-M

\QP18,P19 Identification phase

P38 Entry in C8R0,R4

C8R0 Automatic calling number to reach the groom

C8R4 Call retransmission timer*10s

X.28 PLUS:

Configuration of X28Plus is governed by optional software license (X.28+)

Used to connect an asynchronous device following Sprintnet and Telenet behavior.

If the user is set with Autospeed detection (so-called RAVC12RxP43), the user needs to enter the following sequence:

See also parameter 105-112 and 115-122 in Chapter 9, "Connection Profiles and Parameters."

Virtual Circuit establishment principle.

Three possibilities are offered:

Addressed call case:

Call number-facilities*Call User Data

Call number: 1 to 10 digits.

Facilities: R for reverse charging

Gxx for Closed User Group

Nxxxxxx for NUI

Note Facilities are separated by a coma.

Call User Data: Up to 12 characters.

X.28 Plus Commands

These commands are accessible via an asynchronous terminal intended for the PAD to which it is directly connected.


Table 6-56: X.28+ Commands
Commands Functions PAD Response

STAT

Request for status of virtual call between PAD and terminal

ENGAGED = VC established FREE = VC not established

LIB or CLR

Request to clear the call

LIB or CLR = call cleared

PAR? Parameter numbers

Request for value of one or more parameters

Example: PAR? 1, 2, 5

Note: To determine the values of all the parameters, type PAR?

Parameters followed by their value

Example: PAR 1: 0.2 : 1.5 :1

SET? Parameter numbers: new values,

Modification of a value of one or more parameters

Example: SET? 1: 0.2 : 0.4 : 3

Parameters followed by their value

Example: PAR 1: 0.2 : 1.5 : 1

PROF Profile Number

Choice of a standard profile available in the PAD

RESET

Reset of a call

INT

Transmission of an interrupt

MSET? No. of new parameter values

Generation of PAD parameter positioning message

None or ERROR if refused by the remote

mpAR Parameter number

Generation of PAD parameter positioning message, reading of parameter from remote

Parameters followed by their value

RESET? No. of new parameter values

Generation of PAD parameter positioning message

None or ERROR if refused by the remote

RPAR Parameter numbers

Generation of PAD parameter positioning message, reading pf parameter by the remote

Parameters followed by their value

D or DISC

Clearing of VC

CONT

Return to transfer

TPAR? Parameter number

Request for a value of one or more TELENET parameters

Note: To determine the value of all the parameters, type TPAR?

Parameters followed by their value

Example: TPAR 1: 0.2 : 1.5 : 1

ID (up to 15 digits)

Identification of PSTN network user

ERROR if string is wrong: alpha characters, plus 15 digits

IDOFF

PSTN network user identification facility not used

X.28 plus overview configuration.

C1R1

<port #>: 30 X.28+ type

C12r<port#>

0 27 direct

28 PSTN

29 dedicated line

C13R<port#>

0 ITU-T X.3 profile

C18r<port#> CUG.

C8R0,R4 automatic calling number.

C6R0,R1 NUI/NUA table.

C7R0-R3 Mnemonic table,

C16R0,R1 Welcome page.


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Posted: Thu Jan 25 14:17:23 PST 2001
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