|
|
Use the commands in this chapter to configure Link Access Procedure Balanced (LAPB), X.25, DDN X.25, and Blacker Front-end Encryption (BFE).
For X.25 and LAPB configuration information and examples, refer to the Communication Server Configuration Guide.
To configure an incoming access class on virtual terminals, use the access-class line subcommand.
access-class access-list-number in| access-list-number | An integer between 1 and 199 that you select for the access list. |
None
Line configuration
The access list number is used for both incoming TCP access and incoming PAD access.
In the case of TCP access, the communication server uses the IP access list defined using the access-list command.
For incoming PAD connections, the same numbered X.29 access list is referenced. If you only want to have access restrictions on one of the protocols, you can create an access list that permits all addresses for the other protocol.
The following example configures an incoming access class on virtual terminal line 4.
line vty 4
access-class 4 in
The dagger (+) indicates that the command is documented in another chapter of this manual.
x29 access-list
access-list
line vty (+)
Use the bfe EXEC command to set the communication server to participate in emergency mode or to end participation in emergency mode when your system is configured for x25 bfe-emergency decision and x25 bfe-decision ask.
bfe {enter | leave} interface-type numberEXEC
The following example illustrates how to set the communication server to participate in BFE mode:
cs# bfe enter interface serial 0
encapsulation bfex25
x25 bfe-decision
x25 bfe-emergency
Use the clear x25-vc privileged EXEC command to clear virtual circuits (VCs). This command without any arguments clears all X.25 virtual circuits at once.
clear x25-vc interface-type interface-number [lcn]| interface-type | The interface name. |
| number | The interface unit number. |
| lcn | (Optional.) A virtual circuit. |
Privileged EXEC
The following example illustrates how to clear all VCs:
cs# clear x25-vc
x25 idle
Use the encapsulation bfex25 interface configuration command to configure BFE encapsulation on a communication server attached to a BFE device.
encapsulation bfex25This command has no arguments or keywords.
The default serial encapsulation is HDLC. You must choose an X.25 encapsulation method.
Interface configuration
This encapsulation operates to map between Class A IP addresses and the type of X.121 addresses expected by the BFE encryption device.
The following example sets BFE encapsulation on interface serial 0:
interface serial 0
encapsulation bfex25
bfe
A communication server using DDN X.25 Standard Service can act as either a DTE or a DCE device. Use the encapsulation ddnx25 interface configuration command to set DTE DDN X.25 device operation.
encapsulation ddnx25This command has no arguments or keywords.
The default serial encapsulation is HDLC. You must choose an X.25 encapsulation method.
Interface configuration
This encapsulation operates to map between IP addresses and the type of X.121 addresses expected by the BFE encryption device.
The following example sets DTE DDN X.25 device operation on interface serial 0:
interface serial 0
encapsulation ddnx25
A communication server using DDN X.25 Standard Service can act as either a DTE or a DCE device. Use the encapsulation ddnx25-dce interface configuration command to set DCE DDN X.25 device operation.
encapsulation ddnx25-dceThis command has no arguments or keywords.
The default serial encapsulation is HDLC. You must choose an X.25 encapsulation method.
Interface configuration
This encapsulation operates to map between IP addresses and the type of X.121 addresses expected by the DDN.
The following example sets DCE DDN X.25 device operation on interface serial 0:
interface serial 0
encapsulation ddnx25-dce
Use the encapsulation lapb interface configuration command to run datagrams over a DTE serial interface using the LAPB encapsulation. One end of the link must be DTE and the other end must be DCE.
encapsulation lapbThis command has no arguments or keywords.
The default serial encapsulation is HDLC. You must choose an X.25 encapsulation method.
Interface configuration
The following example sets LAPB DTE encapsulation on interface serial 3:
interface serial 3
encapsulation lapb
lapb protocol
Use the encapsulation lapb-dce interface configuration command to run datagrams over a DCE serial interface using the LAPB encapsulation. One end of the link must be DTE and the other end must be DCE.
encapsulation lapb-dceThis command has no arguments or keywords.
The default serial encapsulation is HDLC. You must choose an X.25 encapsulation method.
Interface configuration
The following example sets LAPB DCE encapsulation on interface serial 3:
interface serial 3
encapsulation lapb-dce
lapb protocol
For DTE operation, use the encapsulation multi-lapb interface configuration command to enable use of multiple local-area network (LAN) protocols on the same line at the same time.
encapsulation multi-lapbThis command has no arguments or keywords.
The default serial encapsulation is HDLC. You must choose an X.25 encapsulation method.
Interface configuration
With the encapsulation multi-lapb command, you can use multiple protocols such as IP, DECnet, and XNS at the same time. Both ends of the line must use the same encapsulation; one end of the link must be DCE and the other end DTE.
The following example illustrates how to set multiple protocols on a LAPB line for DTE operation:
interface serial 0
encapsulation multi-lapb
For DCE operation, use the encapsulation multi-lapb-dce interface configuration command to enable use of multiple LAN protocols on the same line at the same time.
encapsulation multi-lapb-dceThis command has no arguments or keywords.
The default serial encapsulation is HDLC. You must choose an X.25 encapsulation method.
Interface configuration
With the encapsulation multi-lapb-dce command, you can use multiple protocols such as IP, DECnet, and XNS at the same time. Both ends of the line must use the same encapsulation; one end of the link must be DCE and the other end DTE.
The following example illustrates how to set multiple protocols on a LAPB line for DCE operation:
interface serial 0
encapsulation multi-lapb-dce
A communication server using X.25 Level 3 encapsulation can act as a DTE or DCE protocol device on general X.25 networks. Use the encapsulation x25 interface configuration command to set X.25 DTE operation.
encapsulation x25This command has no arguments or keywords.
The default serial encapsulation is HDLC. You must choose an X.25 encapsulation method.
Interface configuration
The following example sets X.25 DTE operation on interface serial 0:
interface serial 0
encapsulation x25
A communication server using X.25 Level 3 encapsulation can act as a DTE or DCE device on general X.25 networks. Use the encapsulation x25-dce interface configuration command to set X.25 DCE operation.
encapsulation x25-dceThis command has no arguments or keywords.
The default serial encapsulation is HDLC. You must choose an X.25 encapsulation method.
Interface configuration
The following example sets X.25 DCE operation on interface serial 0:
interface serial 0
encapsulation x25-dce
Use the lapb hold-queue interface configuration command to define the number of packets to be held until they can be sent over the LAPB connection. Use the no lapb hold-queue command without an argument to remove this command from the configuration file and return to the default value.
lapb hold-queue queue-size| queue-size | Defines the number of packets. A hold queue limit of 0 allows an unlimited number of packets in the hold queue. This argument is optional in the no form of the command. |
12 packets
Interface configuration
The following example illustrates how to set the X.25 hold queue to hold 25 packets:
interface serial 0
lapb hold-queue 25
Use the lapb k interface configuration command to specify the maximum permissible number of outstanding frames, called the window size.
lapb k window-size| window-size | A packet count from 1 to 7. |
7 packets
Interface configuration
The following example changes the LAPB window size (the K parameter) to three packets:
interface serial 0
lapb k 3
Use the lapb n1 interface configuration command to specify the maximum number of bits a frame can hold (the LAPB N1 parameter).
lapb n1 bits| bits | Number of bits from 1088 through 32,840; it must be a multiple of eight. |
12056 bits (1500 bytes)
Interface configuration
It is not necessary to set N1 to an exact value to support a particular X.25 data packet size, although both ends of a connection should have the same N1 value. The N1 parameter serves to avoid processing of any huge frames that result from a "jabbering" interface, an unlikely event.
The Cisco N1 default value corresponds to the hardware interface buffer size. Any changes to this value must allow for an X.25 data packet and LAPB frame overhead.The software supports an X.25 data packet with a maximum packet size plus 3 or 4 bytes of overhead for modulo 8 or 128 operation, respectively, and LAPB frame overhead of 2 bytes of header for modulo 8 operation plus 2 bytes of CRC.
In addition, the various standards bodies specify that N1 be given in bits rather than bytes. While some equipment can be configured using bytes or by automatically adjusting for some of the overhead information present, Cisco devices are configured using the true value of N1.
Table 1-1 specifies the minimum N1 values needed to support a given X.25 data packet. Note that N1 cannot be set to a value less than what is required to support an X.25 data packet size of 128 bytes under modulo 128 operation. This is because all X.25 implementations must be able to support
128-byte data packets.
| Maximum Data in X.25 Packet | Minimum N1 value for X.25 Modulo 8 | Minimum N1 Value for X.25 Modulo 8 |
|---|---|---|
| 128 | 1088 | 1088 |
| 256 | 2104 | 2112 |
| 512 | 4152 | 4160 |
| 1024 | 8240 | 8256 |
| 2048 | 16440 | 16448 |
| 4096 | 32824 | 32832 |
Configuring N1 to be less than 2104 will generate a warning message that X.25 might have problems because some nondata packets can use up to 259 bytes.
The N1 parameter cannot be set to a value larger than the default without first increasing the hardware maximum transmission unit (MTU) size.
The X.25 software will accept default packet sizes and CALLs that specify maximum packet sizes greater than what the LAPB layer will support, but will negotiate the CALLs placed on the interface to the largest value that can be supported. For switched CALLs, the packet size negotiation takes place end-to-end through the Cisco communication server so the CALL will not have a maximum packet size that exceeds the capability of either of the two interfaces involved.
The following example sets the N1 bits to 9600:
interface serial 0
lapb n1 9600
Use the lapb n2 interface configuration command to specify the maximum number of times a data frame can be transmitted (the LAPB N2 parameter).
lapb n2 tries| tries | Retransmission count from 1 through 255 |
20 retransmissions
Interface configuration
The following example sets the N2 retries to 50:
interface serial 0
lapb n2 50
Use the lapb protocol interface configuration command to configure a protocol on the LAPB line.
lapb protocol protocol| protocol | Protocol choice: ip and ipx (Novell IPX) |
IP
Interface configuration
The following example sets IP as the protocol on the LAPB line:
interface serial 1
lapb protocol ip
encapsulation lapb
encapsulation lapb-dce
Use the lapb t1 interface configuration command to set the limit retransmission timer period (the LAPB T1 parameter).
lapb t1 milliseconds| milliseconds | Number of milliseconds from 1 through 64,000 |
3000 milliseconds
Interface configuration
The retransmission timer determines how long a transmitted frame can remain unacknowledged before the LAPB software polls for an acknowledgment.
To determine an optimal value for the retransmission timer, use the privileged EXEC command ping to measure the round-trip time of a maximum-sized frame on the link. Multiply this time by a safety factor that takes into account the speed of the link, the link quality, and the distance. A typical safety factor is 1.5. Choosing a larger safety factor can result in slower data transfer if the line is noisy. However, this disadvantage is minor compared to the excessive retransmissions and effective bandwidth reduction caused by a timer setting that is too small.
The following example sets the T1 retransmission timer to 20,000 milliseconds:
interface serial 0
lapb t1 20000
Use the show interfaces serial EXEC command to display information about a serial interface.
show interfaces serial number| number | Specifies the interface port number. |
EXEC
The following is sample output from the show interfaces serial command for a serial interface using LAPB encapsulation:
cs# show interfaces serial 1
LAPB state is SABMSENT, T1 3000, N1 12056, N2 20, K7,
VS 0, VR 0, RCNT 0, Remote VR 0, Retransmissions 2
IFRAMEs 0/0 RNRs 0/0 REJs 0/0 SABMs 3/0 FRMRs 0/0 DISCs 0/0
LAPB state is DISCONNECT, T1 3000, N1 12000, N2 20, K7, TH 3000
Window is closed
IFRAMEs 12/28 RNRs 0/1 REJs 13/1 SABMs 1/13 FRMRs 3/0 DISCs 0/11
Table 1-2 shows the fields relevant to all LAPB connections.
| Parameter | Description |
|---|---|
| LAPB state is | State of the LAPB protocol. |
| T1 3000, N1 12056, ... | Current parameter settings. |
| VS | Modulo 8 frame number to give to the next outgoing I-frame. |
| VR | Modulo 8 frame number to give to the next I frame expected to be received. |
| RCNT | Number of received I-frames that have not yet been acknowledged. |
| Remote VR | Number of the next I-frame the remote expects to receive. |
| Retransmissions | Count of I-frames that have been retransmitted. |
| Window is closed | No more frames can be transmitted until some outstanding frames have been acknowledged. |
| IFRAMEs | Count of Information frames in the form of sent/received. |
| RNRs | Count of Receiver Not Ready frames in the form of sent/received. |
| REJs | Count of Reject frames in the form of sent/received. |
| SABMs | Count of Set Asynchronous Balanced Mode commands in the form of sent/received. |
| FRMRs | Count of Frame Reject frames in the form of sent/received. |
| DISCs | Count of Disconnect commands in the form of sent/received. |
The following is sample output from the show interfaces command for a serial X.25 interface:
cs# show interfaces serial 1
X25 address 000000010100, state R1, modulo 8, idle 0, timer 0, nvc 1
Window size: input 2, output 2, Packet size: input 128, output 128
Timers: T20 180, T21 200, T22 180, T23 180, TH 0
(configuration on RESTART: modulo 8,
Window size: input 2 output 2, Packet size: input 128, output 128
Channels: Incoming-only none, Two-way 5-1024, Outgoing-only none)
RESTARTs 3/2 CALLs 1000+2/1294+190/0+0/ DIAGs 0/0
The stability of the X.25 protocol requires that some parameters not be changed without a RESTART of the protocol. Any change to these parameters will be held until a RESTART is sent or received. If any of these parameters will change, the configuration on RESTART information will be output as well as the values that are currently in effect.
Table 1-3 describes significant fields shown in the display.
| Field | Description |
|---|---|
| X25 address 000000010100 | Calling address used in the Call Request packet. |
| state R1 | State of the interface. Possible values include:
If the state is R2 or R3, the device is awaiting acknowledgment for a Restart packet. |
| modulo 8 | Modulo value; determines the packet sequence numbering scheme used. |
| idle 0 | Number of minutes the communication server waits before closing idle virtual circuits. |
| timer 0 | Value of the interface timer, which is zero unless the interface state is R2 or R3. |
| nvc 1 | Maximum number of simultaneous virtual circuits permitted to and from a single host for a particular protocol. |
| Window size: input 2, output 2 | Default window size (in packets) for the interface. The x25 facility interface configuration command can be used to override these default values for the switched virtual circuits originated by the communication server. |
| Packet size: input 128, output 128 | Default packet size (in bytes) for the interface. The x25 facility interface configuration command can be used to override these default values for the switched virtual circuits originated by the communication server. |
| Timers: T20 180, T21 200, T22 180, T23 180, TH 0 | Values of the Request packet timers:
|
|
Channels: Incoming-only none | Displays the channel sequence range for this interface. |
| RESTARTs 3/2 | Shows RESTART packet statistics for the interface using the format Sent/Received. |
| CALLs 1000+2/1294+190/0+0 | Shows CALL packet statistics for the interface using these formats:
|
|
DIAGs 0/0 | Shows DIAG packet statistics for the interface using the format Forwarded+Failed forwarded. |
Use the show x25 map EXEC command to display information about configured virtual circuits.
show x25 mapThis command has no arguments or keywords.
EXEC
The following is sample output from the show x25 map command:
cs# show x25 map
Serial0: IP 131.108.170.1 1311001 PERMANENT BROADCAST, 2 LCN: 3 4*
The display shows that three virtual circuits have been configured for the communication server, two for the Serial0 interface, and one for the Serial1 interface.
Table 1-4 describes significant fields shown in the first line of output in the display.
| Field | Description |
|---|---|
| Serial0 | Interface for which this X.25 virtual circuit has been configured. |
| IP | Type of higher-level address that has been configured for this virtual circuit using the x25 map command. |
| 131.108.170.1 | Higher-level address that has been configured for this virtual circuit. |
| 1311001 | X.121 address that has been configured for this virtual circuit. |
| PERMANENT | Address-mapping type that has been configured for the interface in this entry. Possible values include:
|
|
BROADCAST | If broadcasts are enabled for an address mapping, the word BROADCAST also appears on the output line. |
| 2 LCN: | If the number of logical circuit numbers (LCNs) is greater than zero, the line of output also includes the LCN numbers. |
| 3 4 | Indicates the LCNs, if one or more exists. |
| * | Marks the current LCN. |
Use the show x25 remote-red EXEC command to display the one-to-one mapping of the host IP addresses and the remote BFE device's IP addresses.
show x25 remote-redThis command has no arguments or keywords.
EXEC
The following is sample output from the show x25 remote-red command:
cs# show x25 remote-red
Entry REMOTE-RED REMOTE-BLACK INTERFACE
1 21.0.0.3 21.0.0.7 serial3
2 21.0.0.10 21.0.0.6 serial1
3 21.0.0.24 21.0.0.8 serial3
Table 1-5 describes significant fields shown in the display.
| Field | Description |
|---|---|
| Entry | Address mapping entry. |
| REMOTE-RED | Host IP address. |
| REMOTE-BLACK | IP address of the remote BFE device. |
| INTERFACE | Name of interface through which communication with the remote BFE device will take place. |
Use the show x25 vc EXEC command to display active X.25 virtual circuit parameters and statistics. To examine a particular virtual circuit, add an LCN argument to the show x25 vc command.
show x25 vc [lcn]
| lcn | (Optional.) Logical channel number (LCN), from 1 to 4095. |
EXEC
For PVCs, the syntax of the third and sometimes fourth lines of show x25 vc output varies depending on whether the PVC is in a connected or disconnected state, and whether the connection is locally switched.
If the PVC is locally switched and connected, the syntax for the third line of output follows:
Switched PVC to interface name PVC #, connected
If the PVC is locally switched and not connected, the syntax for the third line of output follows:
Switched PVC to interface name PVC #, not connected, PVC state string
The following is sample output from show x25 vc command for an SVC that carries encapsulated IP diagrams:
cs# show x25 vc
LC1: 1, State: D1, Interface: Serial0
Started 0:55:03, last input 0:54:56, output 0:54:56
Connected to IP [10.4.0.32] <->000000320400 Precedent: 0
Window size input: 7, output: 7
Packet size input: 1024, output: 1024
PS: 2 PR: 6 Remote PR: 2 RCNT: 1 RNR: FALSE
Window is closed
Retransmits: 0 Timer (secs): 0 Reassembly (bytes): 0
Held Fragments/Packets: 0/0
Bytes 1111/588 Packets 18/22 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0
Table 1-6 describes significant fields shown in the output.
| Field | Description |
|---|---|
| LCI | Virtual circuit number. |
| State | State of the virtual circuit (which is independent of the states of other virtual circuits); D1 is the normal ready state. (See the CCITT X.25 recommendation for a description of virtual circuit states.) |
| Interface | Interface used for the virtual circuit. |
| Started | Time elapsed since the virtual circuit was created. |
| last input | Time of last input. |
| output | Time of last output. |
| Connected to | Network-protocol address, in brackets, and the X.121 address of the machine to which the communication server is locally connected. |
| Precedent | IP precedence (appears only if you have specified DDN encapsulation). |
| Window size | Window size for the virtual circuit. |
| Packet size | Packet size for the virtual circuit. |
| PS | Current send sequence number. |
| PR | Current receive sequence number. |
| Remote | Last PR number received from the other end of the circuit. |
| RCNT | Count of unacknowledged input packets. |
| RNR | State of the Receiver Not Ready flag; this field is true if the network sends a receiver-not-ready packet. |
| Window is closed | Communication server cannot transmit any more frames until the remote node has acknowledged some outstanding packets. |
| Retransmits | Number of times a supervisory packet (RESET or CLEAR) has been retransmitted. |
| Timer | A nonzero time value if a packet has not been acknowledged or if virtual circuits are being timed for inactivity. |
| Reassembly | Number of bytes received for a partial packet (a packet in which the more data bit is set). |
| Held Fragments/Packets | Number of X.25 packets being held. (In this case, Fragments refers to the X.25 fragmentation of higher-level data packets.) |
| Bytes | Total number of bytes sent and received. The Packets, Resets, RNRs, REJs, and INTs fields show the total sent and received packet counts of the indicated types. (RNR is Receiver Not Ready, REJ is Reject, and INT is Interrupt.) |
Use the x25 accept-reverse interface configuration command to instruct the communication server to accept all reverse charge calls. The no x25 accept-reverse command disables this facility.
x25 accept-reverseThis command has no arguments or keywords.
Disabled
Interface configuration
This command causes the interface to accept reverse charge calls by default. This behavior also can be configured on a per-peer basis using the x25 map interface configuration command.
The following example illustrates how to set acceptance of reverse charge calls:
interface serial 0
x25 accept-reverse
x25 map
Use the x25 address interface configuration command to set the X.121 address of a particular network interface.
x25 address X.121-address| X.121-address | Variable-length X.121 address. The address is assigned by the X.25 network service provider. |
None
Interface configuration
The following example sets the X.121 address for the interface:
interface serial 0
x25 address 00000123005
The address must match that assigned by the X.25 network service provider.
Use the x25 bfe-decision interface configuration command to direct how a communication server configured for x25 bfe-emergency decision will participate in emergency mode.
x25 bfe-decision {no | yes | ask}| no | Prevents the communication server from participating in emergency mode and from sending address translation information to the BFE device. |
| yes | Allows the communication server to participate in emergency mode and to send address translation information to the BFE when the BFE enters emergency mode. The communication server obtains this information from the table created by the x25 remote-red command. |
| ask | Configures the communication server to display an onscreen request to enter the bfe EXEC command. |
no
Interface configuration
The following example shows how to configure interface serial 0 to require an EXEC command from the administrator before it participates in emergency mode. The host IP address is 21.0.0.12, and the address of the remote BFE unit is 21.0.0.1. When the BFE enters emergency mode, the communication server will prompt the administrator for EXEC command bfe enter to direct the communication server to participate in emergency mode.
interface serial 0
x25 bfe-emergency decision
x25 remote-red 21.0.0.12 remote-black 21.0.0.1
x25 bfe-decision ask
bfe
x25 bfe-emergency
x25 remote-red
Use the x25 bfe-emergency interface configuration command to configure the circumstances under which the communication server participates in emergency mode.
x25 bfe-emergency {never | always | decision}never
Interface configuration
The following example shows how to configure interface serial 0 to require an EXEC command from the administrator before it participates in emergency mode. The host IP address is 21.0.0.12, and the address of the remote BFE unit is 21.0.0.1. When the BFE enters emergency mode, the communication server will prompt the administrator for EXEC command bfe enter to direct the communication server to participate in emergency mode.
interface serial 0
x25 bfe-emergency decision
x25 remote-red 21.0.0.12 remote-black 21.0.0.1
x25 bfe-decision ask
bfe
x25 bfe-decision
Use the x25 default interface configuration command to set a default protocol. Use the no x25 default command to remove the protocol specified.
x25 default protocol| protocol | Specifies the protocol; can only be IP, specified by the ip keyword. |
None
Interface configuration
This command specifies the protocol assumed by the communication server to interpret incoming calls with unknown Call User Data. If you do not use the x25 default interface configuration command, the communication server clears any incoming calls with unknown Call User Data.
The following example illustrates how to establish IP as the default protocol for X.25 calls:
interface serial 0
x25 default IP
x25 map
Use the x25 facility interface configuration command to override the default facility settings on a per-call basis for calls originated by the communication server. Use the no x25 facility command to disable the facility.
x25 facility facility-keyword value| facility-keyword | User facility.; see Table 1-7 for a list of supported facilities and their values. |
| value | Facility value; see Table 1-7 for a list of supported facilities and their values. |
No facility sent
Interface configuration
The following example illustrates how to specify a transit delay value in an X.25 configuration:
interface serial 0
x25 facility transit-delay 24000
The following example illustrates how to set an RPOA name and then send the list via the X.25 user facilities:
x25 rpoa green_list 23 35 36
interface serial 0
x25 facility rpoa green_list
x25 map ip 131.108.170.26 10 rpoa green_list
x25 rpoa
Use the x25 hic interface configuration command to set the highest incoming-only virtual circuit number.
x25 hic circuit-number| circuit-number | Virtual circuit number from 1 through 4095, or 0 if there is no incoming-only virtual circuit range. |
0
Interface configuration
This command is applicable only if you have the X.25 switch configured for incoming only. Incoming is from the perspective of the X.25 DTE. If you do not want any outgoing calls from your DCE, configure the lic and hic values and set the ltc and htc values to 0.
The following example illustrates how to set a valid incoming-only virtual circuit range of 1 to 5:
interface serial 0
x25 lic 1
x25 hic 5
x25 ltc 6
x25 lic
Use the x25 hoc interface configuration command to set the highest outgoing-only virtual circuit number.
x25 hoc circuit-number| circuit-number | Virtual circuit number from 1 through 4095, or 0 if there is no outgoing-only virtual circuit range. |
0
Interface configuration
This command is applicable only if you have the X.25 switch configured for outgoing only. Outgoing is from the perspective of the X.25 DTE. If you do not want any incoming calls from your DTE, configure the loc and hoc values and set the ltc and htc values to 0.
The following example illustrates how to set a valid outgoing-only virtual circuit range of 2000 to 2005:
interface serial 0
x25 loc 2000
x25 hoc 2005
x25 loc
Use the x25 hold-queue interface configuration command to modify the maximum number of packets that can be held until a virtual circuit is able to transmit. Use the no x25 hold-queue command without an argument to remove this command from the configuration file and restore the default value.
x25 hold-queue queue-size| queue-size | Defines the VC packet hold queue size. A hold queue value of 0 allows an unlimited number of packets in the hold queue. This argument is optional for the no form of this command. |
10 packets
Interface configuration
If you set the queue-size to 0 when using the no x25 hold-queue command, there will be no hold queue limit. An unlimited hold queue might be appropriate if the interface is configured with a maximum transmission unit (MTU) and IP MTU larger than the X.25 input packet size and X.25 output packet size. If you have configured an MTU and IP MTU larger than the these packet sizes, our X.25 software will fragment the encapsulated IP packet into multiple X.25 frames. This fragmentation might cause the X.25 window to close and the hold queue to become full.
The following example illustrates how to set the X.25 hold queue to hold 25 packets:
interface serial 0
x25 hold-queue 25
A dagger (+) indicates that the command is documented in another chapter.
ip mtu (+)
x25 ips
x25 ops
Use the x25 hold-vc-timer interface configuration command to prevent overruns on some X.25 switches caused by Call Request packets. This command uses the Ignore Destination timer to prevent additional calls to a destination for a given period of time. The no x25 hold-vc-timer command restores the default value for the timer.
x25 hold-vc-timer minutes| minutes | Number of minutes to prevent calls from going to a previously failed destination. Incoming calls still will be accepted. |
0
Interface configuration
Only Call Requests that the communication server originates will be held down; routed X.25 Call Requests are not affected by this parameter.
Upon receiving a Clear Request for an outstanding Call Request, the X.25 support code immediately tries another Call Request if it has more traffic to send, and this action might cause overrun problems.
The following example illustrates how to set the Ignore Destination timer to 3 minutes:
interface serial 0
x25 hold-vc-timer 3
Use the x25 host global configuration command to define a static host name-to-address mapping. Use the no x25 host command to remove the host name.
x25 host name X.121-address [cud call-user-data]| name | Host name. |
| X.121-address | The X.121 address. |
| cud call-user-data | (Optional.) Sets the Call User Data (CUD) field in the X.25 Call Request packet. |
None
Global configuration
The following example illustrates how to specify a static address mapping:
x25 host Willard 4085551212
The following example illustrates how to remove a static address mapping:
no x25 host Willard
Use the x25 htc interface configuration command to set the highest two-way virtual circuit number.
x25 htc circuit-number| circuit-number | Virtual circuit number from 1 through 4095, or 0 if there is no two-way virtual circuit range. |
1024 for X.25 network service interfaces
Interface configuration
This command is applicable if you have the X.25 switch configured for two-way.
The following example illustrates how to set a valid two-way virtual circuit range of 5 to 25:
interface serial 0
x25 ltc 5
x25 htc 25
x25 ltc
The communication server can clear a switched virtual circuit (SVC) after a period of inactivity. Use the x25 idle interface configuration command to set this period.
x25 idle minutes| minutes | Number of minutes in the idle period |
0 (causes the communication server to keep the SVC open indefinitely)
Interface configuration
Both calls originated and terminated by the communication server are cleared; switched virtual circuits are not cleared. To clear one or all virtual circuits at once, use the privileged EXEC command clear x25-vc.
The following example illustrates how to set a 5-minute wait period before an idle circuit is cleared:
interface serial 2
x25 idle 5
clear x25-vc
Use the x25 ip-precedence interface configuration command to enable the ability to open a new virtual circuit based on the IP Type of Service (TOS) field. The command no x25 ip-precedence causes the TOS field to be ignored when opening virtual circuits.
x25 ip-precedenceThis command has no arguments or keywords.
The communication servers open one virtual circuit for all types of service.
Interface configuration
There is a problem associated with this feature in that some hosts send nonstandard data in the TOS field, thus causing multiple, wasteful virtual circuits to be created.
The following example illustrates how to allow new virtual circuits based on the TOS field:
interface serial 3
x25 ip-precedence
Use the x25 ips interface configuration command to set the interface default maximum input packet size to match those of the network.
x25 ips bytes| bytes | Byte count that is one of the following: 16, 32, 64, 128, 256, 512, 1024, 2048, or 4096. |
128 bytes
Interface configuration
X.25 network connections have a default maximum input packet size set by the network administrator. Larger packet sizes require less overhead processing. To send a packet larger than the X.25 packet size over an X.25 virtual circuit, a communication server must break the packet into two or more X.25 packets with the M-bit ("more data" bit) set. The receiving device collects all packets with the M-bit set and reassembles them.
The following example shows how to set the default maximum packet sizes to 512:
interface serial 1
x25 ips 512
x25 ops 512
x25 ops
Use the x25 lic interface configuration command to set the lowest incoming-only virtual circuit number.
x25 lic circuit-number| circuit-number | Virtual circuit number from 1 through 4095, or 0 if there is no incoming-only virtual circuit range. |
0
Interface configuration
This command is applicable only if you have the X.25 switch configured for incoming only. Incoming is from the perspective of the X.25 DTE. If you do not want any outgoing calls from your DCE, configure the lic and hic values and set the ltc and htc values to 0.
This command is applicable if you have the X.25 switch configured for two way virtual circuits.
The following example shows how to set a valid incoming-only virtual circuit range of 1 to 5:
interface serial 0
x25 lic 1
x25 hic 5
x25 ltc 6
x25 hic
Use the x25 linkrestart interface configuration command to force a packet-level restart when the link level resets. This command restarts X.25 Level 3 when errors occur in Level 2 (LAPB). The no x25 linkrestart command disables this function.
x25 linkrestartThis command has no arguments or keywords.
Forcing packet-level restarts is the default and is necessary for networks that expect this behavior.
Interface configuration
The following example illustrates how to disable the link-level restart:
interface serial 3
no x25 linkrestart
Use the x25 loc interface configuration command to set the lowest outgoing-only virtual circuit number.
x25 loc circuit-number| circuit-number | Virtual circuit number from 1 through 4095, or 0 if there is no outgoing-only virtual circuit range. |
0
Interface configuration
This command is applicable only if you have the X.25 switch configured for outgoing only. Outgoing is from the perspective of the X.25 DTE. If you do not want any incoming calls from your DTE, configure the loc and hoc values and set the ltc and htc values to 0.
The following example illustrates how to set a valid outgoing-only virtual circuit range of 2000 to 2005:
interface serial 0
x25 loc 2000
x25 hoc 2005
x25 hoc
Use the x25 ltc interface configuration command to set the lowest two-way virtual circuit number.
x25 ltc circuit-number| circuit-number | Virtual circuit number from 1 through 4095, or 0 if there is no two-way virtual circuit range. |
1
Interface configuration
This command is applicable if you have the X.25 switch configured for two-way.
The following example illustrates how to set a valid two-way virtual circuit range of 5 to 25:
interface serial 0
x25 ltc 5
x25 htc 25
x25 htc
Use the x25 map interface configuration command to set up the LAN protocol-to-X.121 address mapping for the host. Because no defined protocol can dynamically determine such mappings, you must enter a mapping for each host with which the communication server will exchange traffic. Use the no x25 map command with the appropriate network protocol and X.121 address arguments to retract a network protocol-to-X.121 mapping.
x25 map protocol-keyword protocol-address X.121-address [option1... [option6]]| protocol-keyword | Selects the protocol type. Supported protocol keywords are listed in Table 1-8. |
| protocol-address | Specifies the protocol address. |
| X.121-address | Specifies the X.121 address. Both addresses specify the network protocol-to-X.121 mapping. |
| option | (Optional.) Provides additional functionality or the X.25 essential user facilities to the mapping specified. Can be any of the options listed in Table 1-9 (six maximum). |
| Keyword | Protocol |
|---|---|
| ip | IP |
| novell | Novell IPX |
| compressedtcp | TCP header compression |
None
Interface configuration
The broadcast keyword simplifies the configuration of OSPF for nonbroadcast networks that will use X.25.
OSPF treats a nonbroadcast, multiaccess network such as X.25 much the same way it treats a broadcast network in that it requires selection of a designated communication server. In previous releases, this required manual assignment in the OSPF configuration using the neighbor interface communication server configuration command. When the x25 map command is included in the configuration with the broadcast keyword, there is no need to configure any neighbors manually. OSPF will now automatically run over the Frame Relay network as a broadcast network.
The broadcast keyword directs any broadcasts sent through this interface to the specified X.121 address. The following example illustrates how to map IP address 131.08.2.5 to X.121 address 000000010300:
interface serial 0
x25 map ip 131.08.2.5 000000010300 broadcast
The following example illustrates how to set an RPOA name for use in the connection:
x25 rpoa green_list 23 35 36
interface serial 0
x25 facility rpoa green_list
x25 map ip 131.108.170.26 10 rpoa green_list
The following example shows how to add a network user identifier (NUI) to the address map:
interface serial 0
x25 map IP 131.108.174.32 2 nudata "Network User ID 35"
Strings can be quoted, but quotes are not required unless embedded blanks are present.
x25 map
x25 map compressedtcp
Use the x25 map compressedtcp interface configuration command to map compressed TCP traffic to X.121 addresses. The no x25 map compressedtcp command disables TCP header compression for the link.
x25 map compressedtcp IP-address X.121-address [options]| IP-address | The IP address. |
| X.121-address | The X.121 address. |
| options | (Optional.) The same options as those for the x25 map command described in Table 1-9. |
None
Interface configuration
The Call User Data of compressed TCP calls is the single byte 0xD8.
TCP header compression is supported over X.25 links. The implementation of compressed TCP over X.25 uses a virtual circuit (VC) to pass the compressed packets. The noncompressed packets use another VC. The NVC map option cannot be used for TCP header compression, as only one VC can carry compressed TCP header traffic to a given host.
The following example establishes packet compression on interface serial 4:
interface serial 4
ip tcp header-compression
x25 map compressedtcp 131.08.2.5 000000010300
x25 map
Use the x25 modulo interface configuration command to set the packet numbering modulo.
x25 modulo modulus| modulus | Either 8 or 128. The value of the modulo parameter must agree with that of the device on the other end of the X.25 link. |
8
Interface configuration
X.25 supports flow control with a sliding window sequence count. The window counter restarts at zero upon reaching the upper limit, which is called the window modulus.
The following example illustrates how to set the window modulus to 128:
interface serial 0
x25 modulo 128
x25 win
x25 wout
Use the x25 nvc interface configuration command to specify the maximum number of switched virtual circuits (SVCs) that a protocol can have open simultaneously to one host. To increase throughput across networks, you can establish up to eight switched virtual circuits to a host.
x25 nvc count| count | Circuit count from 1 to 8. A maximum of eight VCs can be configured for each protocol/host pair. Protocols that do not tolerate out-of-order delivery, such as encapsulated TCP header compression, will only use one virtual circuit despite this value. |
1
Interface configuration
When the windows and output queues of all existing connections to a host are full, a new virtual circuit will be opened to the designated circuit count. If a new connection cannot be opened, the data is dropped.
The following example illustrates how to set the maximum number of switched virtual circuits that can be open simultaneously to 4:
interface serial 0
x25 nvc 4
Use the x25 ops interface configuration command to set the interface default maximum output packet size to match those of the network.
x25 ops bytes| bytes | Byte count in the range of 16 through 1024. |
128 bytes
Interface configuration
X.25 networks use maximum input packet sizes set by the network administration. Larger packet sizes are better because smaller packets require more overhead processing. To send a packet larger than the X.25 packet size over an X.25 virtual circuit, a communication server must break the packet into two or more X.25 packets with the M-bit ("more data" bit) set. The receiving device collects all packets with the M-bit set and reassembles them.
The following example shows how to set the default maximum packet sizes to 512:
interface serial 1
x25 ips 512
x25 ops 512
x25 ips
Use the encapsulating version of the x25 pvc interface configuration command to establish an encapsulation permanent virtual circuit (PVC). To delete the PVC, use the no x25 pvc command with the appropriate channel number, protocol keyword, and protocol address.
x25 pvc circuit protocol-keyword protocol-address [option]| circuit | Virtual-circuit channel number which must be less than the virtual circuits assigned to the switched virtual circuits (SVCs). |
| protocol-keyword | Protocol type. Supported protocols are listed in Table 1-10. |
| protocol-address | Address of the host at the other end of the PVC. |
| option | (Optional.) PVC's flow control parameters if they differ from the interface defaults. The option arguments add certain features to the mapping specified and can be either of the options listed in Table 1-11. |
| Keyword | Protocol |
|---|---|
| ip | IP |
| novell | Novell IPX |
| compressedtcp | TCP header compression |
None; the PVC window and maximum packet sizes default to the map values or the interface default values.
Interface configuration
You must specify the required network protocol-to-X.121 address mapping with an x25 map command before you can set up a PVC.
x25 map
Use the x25 remote-red interface configuration command to set up the table that lists the BFE nodes (host or gateways) to which the communication server will send packets.
x25 remote-red host-ip-address remote-black Blacker-ip-address| host-IP-address | IP address of the host or a communication server that the packets are being sent to. |
| remote-black | Delimits the addresses for the table being built. |
| Blacker-IP-address | IP address of the remote BFE device in front of the host to which the packet is being sent. |
None
Interface configuration
The table that results from this command provides the address translation information the communication server sends to the BFE when it is in emergency mode.
The following example sets up a short table of BFE nodes for interface serial 0:
interface serial 0
x25 remote-red 131.108.9.3 remote-black 131.108.9.13
x25 remote-red 192.108.15.1 remote-black 192.108.15.26
x25 bfe-decision
Use the x25 rpoa global configuration command to set the packet network carrier. The no x25 rpoa command removes the specified name.
x25 rpoa name number...| name | Recognized Private Operating Agency (RPOA), which must be unique with respect to all other RPOA names. It is used in the x25 facility and x25 map interface configuration commands. |
| number | Number that is used to describe an RPOA; up to 10 numbers are accepted. |
None
Global configuration
This command specifies a list of transit RPOAs to use, referenced by name.
The following example illustrates how to set an RPOA name and then send the list via the X.25 user facilities:
x25 rpoa green_list 23 35 36
interface serial 0
x25 facility rpoa green_list
x25 map ip 131.108.170.26 10 rpoa green_list
x25 facility
x25 map
Use the x25 suppress-called-address interface configuration command to omit the called address in outgoing calls. Use the no x25 suppress-called-address command to reset this command to the default state.
x25 suppress-called-addressThis command has no arguments or keywords.
The called address is sent by default.
Interface configuration
This command omits the called (destination) X.121 address in Call Request packets and is required for networks that expect only subaddresses in the called address field.
The following example illustrates how to suppress or omit the called address in Call Request packets:
interface serial 0
x25 suppress-called-address
Use the x25 suppress-calling-address interface configuration command to omit the calling address in outgoing calls. Use the no x25 suppress-calling-address command to reset this command to the default state.
x25 suppress-calling-addressThis command has no arguments or keywords.
The calling address is sent by default.
Interface configuration
This command omits the calling (source) X.121 address in Call Request packets and is required for networks that expect only subaddresses in the calling address field.
The following example illustrates how to suppress or omit the calling address in Call Request packets:
interface serial 0
x25 suppress-calling-address
Use the x25 t10 interface configuration command to set the limit for the Restart Request retransmission timer (T10) on DCE devices.
x25 t10 seconds| seconds | Amount of time in seconds |
60 seconds
Interface configuration
The following example sets the T10 timer to 30 seconds:
interface serial 0
x25 t10 30
Use the x25 t11 interface configuration command to set the limit for the Call Request Completion timer (T11) on DCE devices.
x25 t11 seconds| seconds | Amount of time in seconds |
180 seconds
Interface configuration
The following example sets the T11 timer to 90 seconds:
interface serial 0
x25 t11 90
Use the x25 t12 interface configuration command to set the limit for the Reset Request retransmission timer (T12) on DCE devices.
x25 t12 seconds| seconds | Amount of time in seconds |
60 seconds
Interface configuration
The following example sets the T12 timer to 30 seconds:
interface serial 0
x25 t12 30
Use the x25 t13 interface configuration command to set the limit for the Clear Request retransmission timer (T13) on DCE devices.
x25 t13 seconds| seconds | Amount of time in seconds |
60 seconds
Interface configuration
The following example sets the T13 timer to 30 seconds:
interface serial 0
x25 t13 30
Use the x25 t20 interface configuration command to set the limit for the Restart Request retransmission timer (T20) on DTE devices.
x25 t20 seconds| seconds | Amount of time in seconds |
180 seconds
Interface configuration
The following example sets the T20 timer to 90 seconds:
interface serial 0
x25 t20 90
Use the x25 t21 interface configuration command to set the limit for the Call Request Completion timer (T21) on DTE devices.
x25 t21 seconds| seconds | Amount of time in seconds |
200 seconds
Interface configuration
The following example sets the T21 timer to 100 seconds:
interface serial 0
x25 t21 100
Use the x25 t22 interface configuration command to set the limit for the Reset Request retransmission timer (T22) on DTE devices.
x25 t22 seconds| seconds | Amount of time in seconds |
180 seconds
Interface configuration
The following example sets the T22 timer to 90 seconds:
interface serial 0
x25 t22 90
Use the x25 t23 interface configuration command to set the limit for the Clear Request retransmission timer (T23) on DTE devices.
x25 t23 seconds| seconds | Amount of time in seconds |
180 seconds
Interface configuration
The following example sets the T23 timer to 90 seconds:
interface serial 0
x25 t23 90
Use the x25 th interface configuration command to instruct the communication server to send an acknowledgment packet when it has received a threshold of data packets it has not acknowledged, instead of waiting until its input window is full. This command improves line responsiveness at the expense of bandwidth.
x25 th delay-count| delay-count | Value between zero and the input window size. A value of 1 sends one Receiver Ready acknowledgment per packet at all times. |
0 (which disables the delayed acknowledgment strategy)
Interface configuration
The communication server sends acknowledgment packets when the number of input packets reaches the count you specify, providing there are no other packets to send. For example, if you specify a count of 1, the communication server can send an acknowledgment per input packet.
The following example sends five Receiver Ready acknowledgments per packet as an input packet delay:
interface serial 1
x25 th 5
x25 win
x25 wout
Use the x25 win interface configuration command to change the default maximum number of unacknowledged incoming packets for the interface.
x25 win packets| packets | Packet count that can range from 1 to one less than the window modulus. |
2 packets
Interface configuration
This command determines how many packets the communication server can receive before sending an X.25 acknowledgment. To maintain high bandwidth utilization, assign this limit the largest number that the network allows.
The following example specifies that five packets must be received before sending an X.25 acknowledgment:
interface serial 1
x25 win 5
x25 modulo
x25 th
x25 wout
Use the x25 wout interface configuration command to change the default maximum number of unacknowledged packets to allow.
x25 wout packets| packets | Packet count that can range from 1 to the window modulus. |
2 packets
Interface configuration
This command determines the default number of packets the communication server can send before waiting for an X.25 acknowledgment. To maintain high bandwidth utilization, assign this limit the largest number that the network allows.
The following example specifies an upper limit of five for the number of outstanding unacknowledged packets for the output window:
interface serial 1
x25 wout 5
x25 modulo
x25 th
x25 win
To limit access to the communication server from certain X.25 hosts, use the x29 access-list global configuration command. To delete an entire access list, use the no form of this command.
x29 access-list access-list-number {deny | permit} X.121-address| access-list-number | Number of the access list. It can be a value between 1 and 199. |
| deny | Denies access and clears call requests immediately. |
| permit | Permits access to the protocol translator. |
| X.121-address | X.121 address, with or without regular expression pattern-matching characters, with which to compare for access. |
None
Global
An access list can contain any number of access list items. The list are processed in the order in which you entered them, with the first match causing the permit or deny condition. If an X.121 address does not match any of the regular expression in the access list, access will be denied.
Access lists take advantage of the message field defined by Recommendation X.29, which describes procedures for exchanging data between two PADs or a PAD and a DTE device.
The UNIX-style regular expression characters allow for pattern matching of characters and character strings in the address. Various pattern-matching constructions are available that will allow many addresses to be matched by a single regular expressions. Refer to the regular expression appendix in this manual for more information.
The following example permits connections to hosts with addresses beginning with the string 31370:
x29 access-list 2 permit ^31370
To create a PAD profile script for use by the translate command, use the x29 profile global configuration command.
x29 profile name parameter:value [parameter:value]| name | Name of the PAD profile script. |
| X.parameter:value | X.3 PAD parameter number and value separated by a colon. You can specify multiple parameter-value pairs. |
None
Global
When an X.25 connection is established, the communication server acts as if an X.29 SET PARAMETER packet had been sent containing the parameters and values set by the x29 profile command and sets the communication server accordingly.
The following profile script turns local edit mode on when the connection is made and establishes local echo and line termination upon receipt of a Return. The name "linemode" is used with the translate command to effect use of this script.
x29 profile linemode 2:1 3:2 15:1
translate
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