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Use the commands in this chapter to configure Link Access Procedure, Balanced (LAPB), X.25 services (X.25, XOT and CMNS), Defense Data Network (DDN) X.25, and the Blacker Front End (BFE). X.25 provides remote terminal access; encapsulation for the IP, DECnet, XNS, ISO CLNS, AppleTalk, Novell IPX, Banyan VINES, and Apollo Domain protocols; and bridging.
X.25 virtual circuits can also be switched as follows:
To translate between X.25 and another protocol, refer to the "Protocol Translation Commands" chapter in the Dial Solutions Command Reference.
For X.25 and LAPB configuration information and examples, refer to the "Configuring X.25 and LAPB" chapter in the Wide-Area Networking Configuration Guide.
To configure an incoming access class on virtual terminals, use the access-class line configuration command.
access-class access-list-number in| access-list-number | An integer between 1 and 199 that you select for the access list. |
| in | Restricts incoming connections between a particular access server and the addresses in the access list. |
No incoming access class is defined.
Line configuration
This command first appeared in Cisco IOS Release 10.3.
The access list number is used for both incoming Transmission Control Protocol (TCP) access and incoming packet assembler/disassembler (PAD) access.
In the case of TCP access, the access server uses the Internet Protocol (IP) access list defined with 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
You can use the master indexes or search online to find documentation of related commands.
access-list
line vty
x29 access-list
To allow the router to participate in emergency mode or to end participation in emergency mode when the interface is configured for x25 bfe-emergency decision and x25 bfe-decision ask, use the bfe EXEC command.
bfe {enter | leave} type number| enter | Causes the Cisco IOS software to send a special address translation packet that includes an enter emergency mode command to the Blacker Front End (BFE) if the emergency mode window is open. If the BFE is already in emergency mode, this command enables the sending of address translation information. |
| leave | Disables the sending of address translation information from the Cisco IOS software to the BFE when the BFE is in emergency mode. |
| type | Interface type. |
| number | Interface number. |
EXEC
This command first appeared in Cisco IOS Release 10.3.
The following example enables an interface to participate in BFE emergency mode:
bfe enter serial 0
You can use the master indexes or search online to find documentation of related commands.
encapsulation x25 bfe
x25 bfe-decision
x25 bfe-emergency
Use the clear x25 privileged EXEC command to restart an X.25 or CMNS service, to clear an SVC, or to reset a PVC.
clear x25 {serial number | cmns-interface mac-address} [vc-number]| serial number | Local serial interface being used for X.25 service. |
| cmns-interface mac-address | Local CMNS interface (an Ethernet, Token Ring, or FDDI interface) and MAC address of the remote device; this information identifies a CMNS service. |
| vc-number | (Optional) SVC or PVC number, in the range 1 to 4095. If specified, the SVC is cleared or the PVC is reset. If not specified, the X.25 or CMNS service is restarted. |
Privileged EXEC
This command first appeared in Cisco IOS Release 11.2 F. (This command replaces the clear x25-vc command, which first appeared in Cisco IOS Release 8.3.)
This command form is used to disrupt service forcibly on an individual circuit or on all circuits using a specific X.25 service or CMNS service.
If this command is used without the vc-number value, a restart event is initiated, which implicitly clears all SVCs and resets all PVCs.
The following command clears the SVC or resets the PVC specified:
clear x25 serial 0 1
The following command forces an X.25 restart, which implicitly clears all SVCs and resets all PVCs using the interface:
clear x25 serial 0
The following command restarts the specified CMNS service (if active), which implicitly clears all SVCs using the service:
clear x25 ethernet 0 0001.0002.0003
You can use the master indexes or search online to find documentation of related commands.
This command is replaced by the clear x25 command.
To clear an XOT SVC or reset an XOT PVC, use the clear xot EXEC command.
clear xot remote ip-address port local ip-address port| remote ip-address port | Remote IP address and port number of an XOT connection ID. |
| local ip-address port | Local IP address and port number of an XOT connection ID. |
EXEC
This command first appeared in Cisco IOS Release 11.2 F.
Each SVC or PVC supported by the XOT service uses a TCP connection to communicate X.25 packets. A TCP connection is uniquely identified by the data quartet: remote IP address, remote TCP port, local IP address, and local TCP port. This command form is used to forcibly disrupt service on an individual XOT circuit.
XOT connections are sent to TCP port 1998, so XOT connections originated by the router will have that remote port number, and connections received by the router will have that local port number.
The following command will clear or reset, respectively, the SVC or PVC using the TCP connection identified:
clear xot remote 1.1.1.1 1998 local 2.2.2.2 2000
You can use the master indexes or search online to find documentation of related commands.
To enable the Connection-Mode Network Service (CMNS) on a nonserial interface, use the cmns enable interface configuration command. To disable this capability, use the no form of this command.
cmns enableThis command has no arguments or keywords.
Each nonserial interface must be explicitly configured to use CMNS.
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
After this command is processed on the LAN interfaces--Ethernet, Fiber Distributed Data Interface (FDDI), and Token Ring--all the X.25-related interface configuration commands are made available.
The following example enables CMNS on Ethernet interface 0:
interface ethernet 0
cmns enable
You can use the master indexes or search online to find documentation of related commands.
To exchange datagrams over a serial interface using LAPB encapsulation, use the encapsulation lapb interface configuration command.
encapsulation lapb [dte | dce] [multi | protocol]| dte | (Optional) Specifies operation as a data terminal equipment (DTE) device. This is the default LAPB mode. |
| dce | (Optional) Specifies operation as a data communications equipment (DCE) device. |
| multi | (Optional) Specifies use of multiple local-area network (LAN) protocols to be carried on the LAPB line. |
| protocol | (Optional) A single protocol to be carried on the LAPB line. A single protocol can be one of the following: apollo, appletalk, clns (ISO CLNS), decnet, ip, ipx (Novell IPX), vines, and xns. IP is the default protocol. |
The default serial encapsulation is High-Level Data Link Control (HDLC). You must explicitly configure a LAPB encapsulation method.
DTE operation is the default LAPB mode. IP is the default protocol.
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
The dte, dce, multi and protocol argument forms first appeared in Cisco IOS Release 10.3
LAPB encapsulations are appropriate only for private connections, where you have complete control over both ends of the link. Connections to X.25 networks should use an X.25 encapsulation configuration, which operates the X.25 Layer 3 protocol above a LAPB Layer 2.
One end of the link must be a logical DCE, and the other end a logical DTE. (This assignment is independent of the interface's hardware DTE or DCE identity.)
Both ends of the LAPB link must specify the same protocol encapsulation.
LAPB encapsulation is supported on serial lines configured for dial-on-demand routing (DDR). It can be configured on DDR synchronous serial and Integrated Services Digital Network (ISDN) interfaces and on DDR dialer rotary groups. It is not supported on asynchronous dialer interfaces.
A single-protocol LAPB encapsulation exchanges datagrams of the given protocol, each in a separate LAPB information frame. You must configure the interface with the protocol-specific parameters needed--for example, a link that carries IP traffic will have an IP address defined for the interface.
A multiprotocol LAPB encapsulation can exchange any or all of the protocols allowed for a LAPB interface. It exchanges datagrams, each in a separate LAPB information frame. Two bytes of protocol identification data precede the protocol data. You need to configure the interface with all the protocol-specific parameters needed for each protocol carried.
Beginning with Cisco IOS Release 11.0, multiprotocol LAPB encapsulation supports transparent bridging. This feature requires use of the encapsulation lapb multi command followed by the bridge-group command, which identifies the bridge group associated with multiprotocol LAPB encapsulation. This feature does not support use of the encapsulation lapb protocol command with a bridge keyword.
Beginning with Release 10.3, LAPB encapsulation supports the priority and custom queueing features.
The following example sets the operating mode as DTE and specifies that AppleTalk protocol traffic will be carried on the LAPB line:
interface serial 1
encapsulation lapb dte appletalk
You can use the master indexes or search online to find documentation of related commands.
bridge-group
To specify a serial interface's operation as an X.25 device, use the encapsulation x25 interface configuration command.
encapsulation x25 [dte | dce] [ddn | bfe] | [ietf]| dte | (Optional) Specifies operation as a DTE. This is the default X.25 mode. |
| dce | (Optional) Specifies operation as a DCE. |
| ddn | (Optional) Specifies DDN encapsulation on an interface using DDN X.25 Standard Service. |
| bfe | (Optional) Specifies BFE encapsulation on an interface attached to a BFE device. |
| ietf | (Optional) Specifies that the interface's datagram encapsulation defaults to use of the Internet Engineering Task Force (IETF) standard method, as defined by RFC 1356. |
The default serial encapsulation is HDLC. You must explicitly configure an X.25 encapsulation method.
DTE operation is the default X.25 mode. Cisco's traditional X.25 encapsulation method is the default.
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0. The dte, dce, ddn, bfe and ietf keywords first appeared in Cisco IOS Release 10.3
One end of an X.25 link must be a logical DCE and the other end a logical DTE. (This assignment is independent of the interface's hardware DTE or DCE identity.) Typically, when connecting to a public data network (PDN), the customer equipment acts as the DTE and the PDN attachment acts as the DCE.
Cisco has long supported the encapsulation of a number of datagram protocols, using a standard means when available and a proprietary means when necessary. More recently the IETF adopted a standard, RFC 1356, for encapsulating most types of datagram traffic over X.25. X.25 interfaces use Cisco's traditional method unless explicitly configured for IETF operation; if the ietf keyword is specified, that standard is used unless Cisco's traditional method is explicitly configured. For details see the x25 map command.
You can configure a router attaching to the Defense Data Network (DDN) or to a Blacker Front End (BFE) device to use their respective algorithms to convert between IP and X.121 addresses by using the ddn or bfe option, respectively. An IP address must be assigned to the interface, from which the algorithm will generate the interface's X.121 address. For proper operation, this X.121 address must not be modified.
A router DDN attachment can operate as either a DTE or a DCE device. A BFE attachment can operate only as a DTE device. The ietf option is not available if either the ddn or bfe option is selected.
The following example configures the interface for connection to a BFE device:
interface serial 0
encapsulation x25 bfe
You can use the master indexes or search online to find documentation of related commands.
To specify a period during which a link will remain connected, even if a brief hardware outage occurs, use the lapb interface-outage interface configuration command.
lapb interface-outage milliseconds| milliseconds | Number of milliseconds a hardware outage can last without having the protocol disconnect the service. The default is 0 ms, which disables this feature. |
0 ms, which disables this feature.
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
If a hardware outage lasts longer than the LAPB hardware outage period you select, normal protocol operations will occur. The link will be declared down and, when it is restored, a link setup will be initiated.
The following example sets the interface outage period to 100 ms. The link remains connected for outages equal to or shorter than that period.
encapsulation lapb dte ip
lapb interface-outage 100
To specify the maximum permissible number of outstanding frames, called the window size, use the lapb k interface configuration command.
lapb k window-size| window-size | Frame count. It can be a value from 1 to the modulo size minus 1 (the maximum is 7 if the modulo size is 8; it is 127 if the modulo size is 128). The default is 7 frames. |
7 frames
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
If the window size is changed while the protocol is up, the new value takes effect only when the protocol is reset. You will be informed that the new value will not take effect immediately.
When using the LAPB modulo 128 mode (extended mode), you must increase the window parameter k to send a larger number of frames before acknowledgment is required. This increase is the basis for the router's ability to achieve greater throughput on high-speed links that have a low error rate.
This configured value must match the value configured in the peer X.25 switch. Nonmatching values will cause repeated LAPB reject (REJ) frames.
The following example sets the LAPB window size (the k parameter) to 10 frames:
interface serial 0
lapb modulo
lapb k 10
You can use the master indexes or search online to find documentation of related commands.
To specify the LAPB basic (modulo 8) or extended (modulo 128) protocol mode, use the lapb modulo interface configuration command.
lapb modulo modulus| modulus | Either 8 or 128. The value 8 specifies LAPB's basic mode; the value 128 specifies LAPB's extended mode. The default is 8. |
Modulo 8
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
The modulo parameter determines which of LAPB's two modes is to be used. The modulo values derive from the fact that basic mode numbers information frames between 0 and 7, whereas extended mode numbers them between 0 and 127. Basic mode is widely available and is sufficient for most links. Extended mode is an optional LAPB feature that may achieve greater throughput on high-speed links that have a low error rate.
The LAPB operating mode may be set on X.25 links as well as LAPB links. The X.25 modulo is independent of the LAPB layer modulo. Both ends of a link must use the same LAPB mode.
When using modulo 128 mode, you must increase the window parameter k to send a larger number of frames before acknowledgment is required. This increase is the basis for the router's ability to achieve greater throughput on high-speed links that have a low error rate.
If the modulo value is changed while the protocol is up, the new value takes effect only when the protocol is reset. You will be informed that the new value will not take effect immediately.
The following example configures a high-speed X.25 link to use LAPB's extended mode:
interface serial 1
encapsulation x25
lapb modulo 128
lapb k 40
clock rate 2000000
You can use the master indexes or search online to find documentation of related commands.
To specify the maximum number of bits a frame can hold (the LAPB N1 parameter), use the lapb n1 interface configuration command.
lapb n1 bits| bits | Maximum number of bits in multiples of eight. The minimum and maximum range is dynamically set. Use the question mark (?) to view the range. |
The largest (maximum) value available for the particular interface is the default. The Cisco IOS software dynamically calculates N1 whenever you change the maximum transmission unit (MTU), the L2/L3 modulo, or compression on a LAPB interface.
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
 | Caution The LAPB N1 parameter provides little benefit beyond the interface MTU and can easily cause link failures if misconfigured. Cisco recommends that this parameter be left at its default value. |
The Cisco IOS software uses the following formula to determine the minimum N1 value:
(128 (default packet size) + LAPB overhead + X.25 overhead + 2 bytes of CRC) * 8
The Cisco IOS software uses the following formula to determine for the maximum N1 value:
(hardware MTU + LAPB overhead + X.25 overhead + 2 bytes of CRC) * 8
LAPB overhead is 2 bytes for modulo 8 and 3 bytes for modulo 128.
X.25 overhead is 3 bytes for modulo 8 and 4 bytes for modulo 128.
You need not set N1 to an exact value to support a particular X.25 data packet size. The N1 parameter prevents the processing of any huge frames that result from a "jabbering" interface, an unlikely event.
In addition, the various standards bodies specify that N1 be given in bits rather than bytes. While some equipment can be configured in bytes or will automatically adjust for some of the overhead information present, Cisco devices are configured using the true value, in bits, of N1.
You cannot set the N1 parameter to a value less than that required to support an X.25 data packet size of 128 bytes. All X.25 implementations must be able to support 128-byte data packets. Moreover, if you configure N1 to be less than 2104 bits, you receive a warning message that X.25 might have problems because some nondata packets can use up to 259 bytes.
You cannot set the N1 parameter to a value larger than the default unless the hardware MTU size is first increased.
The X.25 software accepts default packet sizes and calls that specify maximum packet sizes greater than those the LAPB layer supports, but negotiates 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 router so the call will not have a maximum packet size that exceeds the capability of either of the two interfaces involved.
The following example shows how to use the question mark (?) command to display the minimum and maximum N1 value. In this example, X.25 encapsulation has both the LAPB and X.25 modulo set to 8. Any violation of this N1 range results in an "Invalid input" error message.
router# interface serial 1
router(config)# lapb n1 ?
<1080-12056> LAPB N1 parameter (bits; multiple of 8)
The following example sets the N1 bits to 16440:
interface serial 0
lapb n1 16440
mtu 2048
You can use the master indexes or search online to find documentation of related commands.
mtu
To specify the maximum number of times a data frame can be transmitted (the LAPB N2 parameter), use the lapb n2 interface configuration command.
lapb n2 tries| tries | Transmission count. It can be a value from 1 to 255. The default is 20 transmissions. |
20 transmissions
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
The following example sets the N2 tries to 50:
interface serial 0
lapb n2 50
This command is obsolete. It has been replaced by the [protocol | multi] option of the encapsulation lapb command.
To set the retransmission timer period (the LAPB T1 parameter), use the lapb t1 interface configuration command.
lapb t1 milliseconds| milliseconds | Time in milliseconds. It can be a value from 1 to 64000. The default is 3000 ms. |
3000 ms
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
The retransmission timer determines how long a transmitted frame can remain unacknowledged before the LAPB software polls for an acknowledgment. The design of the LAPB protocol specifies that a frame is presumed to be lost if it is not acknowledged within T1; a T1 value that is too small may result in duplicated control information, which can severely disrupt service.
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 2000 ms:
interface serial 0
lapb t1 2000
To set the T4 idle timer, after which the Cisco IOS software sends out a Poll packet to determine whether the link has suffered an unsignaled failure, use the lapb t4 interface configuration command.
lapb t4 seconds| seconds | Number of seconds between reception of the last frame and the transmission of the outgoing Poll. The default value is 0 seconds, which disables the T4 timer feature. |
0 seconds, which disables the T4 timer feature.
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
Any nonzero T4 duration must be greater than T1, the LAPB retransmission timer period.
The following example will poll the other end of an active link if it has been 10 seconds since the last frame was received. If the far host has failed, the service will be declared down after n2 tries are timed out.
interface serial0
encapsulation x25
lapb t4 10
You can use the master indexes or search online to find documentation of related commands.
To enable all packet assembler/disassembler (PAD) commands and connections between PAD devices and access servers, use the service pad global configuration command. Use the no form of this command to disable this service.
service pad [cmns]| cmns | (Optional) Specifies sending and receiving of PAD calls over CMNS. |
All PAD commands and associated connections are enabled. PAD services over XOT or CMNS are not enabled.
Global configuration
This command first appeared in Cisco IOS Release 10.0. The cmns option first appeared in Cisco IOS Release 11.3.
If service pad is disabled, the EXEC pad command and all PAD related configurations, such as X.29, are unrecognized, as shown in the following example:
Router(config)# no service pad
Router(config)# x29 ?
% Unrecognized command
Router(config)# exit
Router# pad ?
% Unrecognized command
If service pad is enabled, the EXEC pad command and access to an X.29 configuration is granted as shown in the following example:
Router# config terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)# service pad
Router(config)# x29 ?
access-list Define an X.29 access list
inviteclear-time Wait for response to X.29 Invite Clear message
profile Create an X.3 profile
Router# pad ?
WORD X121 address or name of a remote system
In the following example, PAD services over CMNS are enabled:
! Enable CMNS on a nonserial interface
interface ethernet0
cmns enable
!
!Enable inbound and outbound PAD over CMNS service
service pad cmns
!
! Specify an X.25 route entry pointing to an interface's CMNS destination MAC address
x25 route ^2193330 interface Ethernet0 mac 00e0.b0e3.0d62
Router# show x25 vc
SVC 1, State: D1, Interface: Ethernet0
Started 00:00:08, last input 00:00:08, output 00:00:08
Line: 0 con 0 Location: console Host: 2193330
connected to 2193330 PAD <--> CMNS Ethernet0 00e0.b0e3.0d62
Window size input: 2, output: 2
Packet size input: 128, output: 128
PS: 2 PR: 3 ACK: 3 Remote PR: 2 RCNT: 0 RNR: no
P/D state timeouts: 0 timer (secs): 0
data bytes 54/19 packets 2/3 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0
You can use the master indexes or search online to find documentation of related commands.
cmns enable
show x25 vc
x29 access-list
x29 profile
To permit incoming XOT Calls to be accepted as a PAD session, use the service pad from-xot global configuration command. Use the no form of this command to disable this service.
service pad from-xotThis command has no arguments or keywords.
Incoming XOT connections are ignored.
Global configuration
This command first appeared in Cisco IOS Release 11.2 F.
If service pad from-xot is enabled, the Calls received using the XOT service may be accepted for processing a PAD session.
The following example prevents incoming XOT Calls from being accepted as a PAD session:
no service pad from-xot
You can use the master indexes or search online to find documentation of related commands.
x29 access-list
x29 profile
x25 route
To permit outgoing PAD sessions to use routes to an XOT destination, use the service pad to-xot global configuration command. Use the no form of this command to disable this service.
service pad to-xotThis command has no arguments or keywords.
XOT routes pointing to XOT are not considered.
Global configuration
This command first appeared in Cisco IOS Release 11.2 F.
If service pad to-xot is enabled, the configured routes to XOT destinations may be used when the router determines where to send a PAD Call, as show in the following example:
service pad to-xot
You can use the master indexes or search online to find documentation of related commands.
x29 access-list
x29 profile
x25 route
To display X.25 Level 3 parameters for LAN interfaces (such as Ethernet or Token Ring) and other information pertaining to Connection-Mode Network Service (CMNS) traffic activity, use the show cmns EXEC command.
show cmns [type number]| type | (Optional) Interface type. |
| number | (Optional) Interface number. |
EXEC
This command first appeared in Cisco IOS Release 10.0.
The following is sample output from the show cmns command for an Ethernet interface:
Router# show cmns
Ethernet1 is administratively down, line protocol is down
Hardware address is 0000.0c02.5f4c, (bia 0000.0c2.5f4c), state R1
Modulo 8, idle 0, timer 0, nvc 1
Window size: input 2, output 2, Packet size: input 128, output 128
Timer: TH 0
Channels: Incoming-only none, Two-way 1-4095, Outgoing-only none
RESTARTs 0/0 CALLs 0+0/0+0/0+0 DIAGs 0/0
Table 25 describes significant fields shown in the display.
| Field | Description |
|---|---|
| Ethernet1 is administratively down | Interface is currently active and inserted into network (up) or inactive and not inserted (down), or disabled (administratively down). |
| line protocol is {up | down} | Indicates whether the software processes that handle the line protocol recognize the interface as usable. |
| Hardware address | Media access control (MAC) address for this interface. |
| bia | Burned-in address. |
| state R1 | State of the interface. R1 is normal ready state. (The state should always be R1.) |
| Modulo 8 | Modulo value; determines the packet sequence numbering scheme used. |
| idle 0 | Number of minutes the Cisco IOS software waits before closing idle virtual circuits. |
| timer 0 | Value of the interface time; should always be zero. |
| nvc 1 | Maximum number of simultaneous virtual circuits permitted to and from a single host for a particular protocol. |
| Window size: | Default window sizes (in packets) for the interface. (CMNS cannot originate or terminate calls.) |
| input 2 | Default input window size is two packets. |
| output 2 | Default output window size is two packets. |
| Packet size: | Default packet sizes for the interface. (CMNS cannot originate or terminate calls). |
| input 128 | Default input maximum packet size is 128 bytes. |
| output 128 | Default output maximum packet size is 128 bytes. |
| TH 0 | X.25 delayed acknowledgment threshold. Should always be zero. |
| Channels: Incoming-only none, Two-way 1-4095, Outgoing-only none | Virtual circuit ranges for this interface per Logical Link Control, type 2 (LLC2) connection. |
| RESTARTs 0/0 | Restarts sent/received. |
| CALLs 0+0/0+0/0+0 | Successful calls + failed calls/calls sent + calls failed/calls received + calls failed. |
| DIAGs 0/0 | Diagnostic messages sent and received. |
You can use the master indexes or search online to find documentation of related commands.
show interfaces serial
To display information about a serial interface, use the show interfaces serial EXEC command.
show interfaces serial number| number | Interface port number. |
EXEC
This command first appeared in Cisco IOS Release 10.0.
The following is a partial sample output from the show interfaces serial command for a serial interface using LAPB encapsulation:
Router# show interfaces serial 1
LAPB state is SABMSENT, T1 3000, N1 12056, N2 20, k7,Protocol ip
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
Table 26 shows the fields relevant to all LAPB connections.
| Field | Description |
|---|---|
| LAPB state is | State of the LAPB protocol. |
| T1 3000, N1 12056,... | Current parameter settings. |
| Protocol | Protocol encapsulated on a LAPB link; this field is not present on interfaces configured for multiprotocol LAPB or X.25 encapsulations. |
| VS | Modulo 8 frame number of the next outgoing information frame. |
| VR | Modulo 8 frame number of the next information frame expected to be received. |
| RCNT | Number of received information frames that have not yet been acknowledged. |
| Remote VR | Number of the next information frame the remote device expects to receive. |
| Retransmissions | Count of current retransmissions due to expiration of T1. |
| Window is closed | No more frames can be transmitted until some outstanding frames have been acknowledged. This message should be displayed only temporarily. |
| 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 a partial sample output from the show interfaces command for a serial X.25 interface:
Router# 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
Channels: Incoming-only none, Two-way 1-1024, Outgoing-only none
(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 are held until a restart is sent or received. If any of these parameters changes, the configuration on restart information will be output as well as the values that are currently in effect.
Table 27 describes significant fields shown in the display.
| Field | Description |
|---|---|
| X25 address 000000010100 | Address used to originate and accept calls. |
| state R1 | State of the interface. Possible values are
If the state is R2 or R3, the interface is awaiting acknowledgment of a Restart packet. |
| modulo 8 | Modulo value; determines the packet sequence numbering scheme used. |
| idle 0 | Number of minutes the Cisco IOS software waits before closing idle virtual circuits that it originated or accepted. |
| timer 0 | Value of the interface timer, which is zero unless the interface state is R2 or R3. |
| nvc 1 | Default 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 sizes (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 router. |
| Packet size: input 128, output 128 | Default maximum packet sizes (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 router. |
| Timers: T20 180, T21 200, T22 180, T23 180 | Values of the X.25 timers:
|
|
TH0 | Packet acknowledgment threshold (in packets). This value determines how many packets are received before an explicit acknowledgment is sent. The default value (0) sends an explicit acknowledgment only when the incoming window is full. |
| Channels: Incoming-only none
Two-way 5-1024 Outgoing-only none | Displays the virtual circuit ranges 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 | Successful calls sent + failed calls/calls received + calls failed/calls forwarded + calls failed. Calls forwarded are counted as calls sent. |
| DIAGs 0/0 | Diagnostic messages sent and received. |
You can use the master indexes or search online to find documentation of related commands.
To display active Logical Link Control, type 2 (LLC2) connections, use the show llc2 EXEC command.
show llc2cThis command has no arguments or keywords.
EXEC
This command first appeared in Cisco IOS Release 10.0.
The following is sample output from the show llc2 command:
Router# show llc2
TokenRing0 DTE=1000.5A59.04F9,400022224444 SAP=04/04, State=NORMAL
V(S)=5, V(R)=5, Last N(R)=5, Local Window=7, Remote Window=127
ack-max=3, n2=8, Next timer in 7768
xid-retry timer 0/60000 ack timer 0/1000
p timer 0/1000 idle timer 7768/10000
rej timer 0/3200 busy timer 0/9600
ack-delay timer 0/3200
CMNS Connections to:
Address 1000.5A59.04F9 via Ethernet2
Protocol is up
Interface type X25-DCE RESTARTS 0/1
Timers: T10 1 T11 1 T12 1 T13 1
The display includes a CMNS addendum, indicating that LLC2 is running with CMNS. When LLC2 is not running with CMNS, the show llc2 command does not display a CMNS addendum.
Table 28 describes significant fields shown in the display.
| Field | Description |
|---|---|
| TokenRing0 | Name of interface on which the session is established. |
| DTE=1000.5A59.04F9, 400022224444 | Address of the station to which the router is transmitting on this session. (The address is the MAC address of the interface on which the connection is established, except when Local Acknowledgment or SDLLC is used, in which case the address used by the router is shown as in this example, following the DTE address and separated by a comma.) |
| SAP=04/04 | Other station's and router's (remote/local) service access point (SAP) for this connection. The SAP is analogous to a "port number" on the router and allows for multiple sessions between the same two stations. |
| State= | Current state of the LLC2 session, which can be any of the following:
|
|
V(S)=5 | Sequence number of the next information frame this station will send. |
| V(R)=5 | Sequence number of the next information frame this station expects to receive from the other station. |
| Last N(R)=5 | Last sequence number of this station's transmitted frames acknowledged by the remote station. |
| Local Window=7 | Number of frames this station may send before requiring an acknowledgment from the remote station. |
| Remote Window=127 | Number of frames this station can accept from the remote station. |
| ack-max=3, n2=8 | Value of these parameters, as given in the previous configuration section. |
| Next timer in 7768 | Number of milliseconds before the next timer, for any reason, goes off. |
| xid-retry timer 0/60000 .... | A series of timer values in the form of next-time/time-between, where "next-time" is the next time, in milliseconds, that the timer will wake, and "time-between" is the time, in milliseconds, between each timer wakeup. A "next-time" of zero indicates that the given timer is not enabled, and will never wake. |
| CMNS Connections to | CMNS addendum when LLC2 is running with the CMNS protocol contains the following:
|
| serial number | (Optional) Keyword serial and number of the serial interface used for X.25. |
| cmns-interface mac mac-address | (Optional) Local CMNS interface type and number, plus the MAC address of the remote device. CMNS interface types are Ethernet, Token Ring, or FDDI. The interface numbering scheme depends on the router interface hardware. |
EXEC
This command first appeared in Cisco IOS Release 11.2 F.
The following show x25 interface sample output displays X.25 information about VCs on serial interface 0:
Router# show x25 interface serial 0
SVC 1, State: D1, Interface: Serial0
Started 00:13:52, last input 00:00:05, output never
Connects 3334 <-> ip 3.3.3.4
Call PID ietf, Data PID none
Window size input: 7, output: 7
Packet size input: 512, output: 512
PS: 0 PR: 6 ACK: 1 Remote PR: 0 RCNT: 5 RNR: no
P/D state timeouts: 0 timer (secs): 0
data bytes 0/2508 packets 0/54 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0
SVC 32, State: D1, Interface: Serial0.11
Started 00:16:53, last input 00:00:37, output 00:00:28
Connects 3334 <-> clns
Call PID cisco, Data PID none
Window size input: 7, output: 7
Packet size input: 512, output: 512
PS: 5 PR: 4 ACK: 4 Remote PR: 4 RCNT: 0 RNR: no
P/D state timeouts: 0 timer (secs): 0
data bytes 378/360 packets 21/20 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0
To display information about configured address maps, use the show x25 map EXEC command.
show x25 mapThis command has no arguments or keywords.
EXEC
This command first appeared in Cisco IOS Release 10.0.
The show x25 map command shows information about the following:
The following is sample output from the show x25 map command:
Router# show x25 map
Serial0: X.121 1311001 <--> ip 172.20.170.1
PERMANENT, BROADCAST, 2 VCS: 3 4*
Serial0: X.121 1311005 <--> appletalk 128.1
PERMANENT
Serial1: X.121 2194441 cud hello <--> pad
PERMANENT, windowsize 5 5, accept-reverse, idle 5
Serial1: X.121 1311005 <--> bridge
PERMANENT, BROADCAST
Serial2: X.121 001003 <--> apollo 1.3,
appletalk 1.3,
ip 172.20.1.3,
decnet 1.3,
novell 1.0000.0c04.35df,
vines 00000001:0003,
xns 1.0000.0c04.35df,
clns
PERMANENT, NVC 8, 1 VC: 1024
Table 29 describes fields shown in the display.
| Field | Description |
|---|---|
| Serial0 | Interface on which this map is configured. |
| X.121 1311001 | X.121 address of the mapped encapsulation host. |
| ip 172.20.170.1 | Type and address of the higher-level protocol(s) mapped to the remote host. Bridge maps do not have a higher-level address; all bridge datagrams are sent to the mapped X.121 address. CLNS maps refer to a configured neighbor as identified by the X.121 address. |
| PERMANENT | Address-mapping type that has been configured for the interface in this entry. Possible values include the following:
|
|
BROADCAST | If any options are configured for an address mapping, they are listed; the example shows a map that is configured to forward datagram broadcasts to the mapped host. |
| 2 VCs: | If the map has any active virtual circuits, they are identified. |
| 3 4* | Identifies the circuit number of the active virtual circuits. The asterisk (*) marks the virtual circuit last used to send data.
Note that a single protocol virtual circuit can be associated with a multiprotocol map. |
To display the one-to-one mapping of the host IP addresses and the remote BFE device's IP addresses, use the show x25 remote-red EXEC command.
show x25 remote-redThis command has no arguments or keywords.
EXEC
This command first appeared in Cisco IOS Release 10.0.
The following is sample output from the show x25 remote-red command:
Router# 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 30 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. |
To display the X.25 routing table, use the show x25 route EXEC command.
show x25 routeThis command has no arguments or keywords.
EXEC
This command first appeared in Cisco IOS Release 10.0.
The following is sample output from the show x25 route command:
Router# show x25 route
# Match Substitute Route To
1 ^1311001$ Serial0, 0 uses
2 ^1311002$ xot 172.20.170.10
Table 31 describes significant fields shown in the display.
| Field | Description |
|---|---|
| # | Number identifying the entry in the X.25 routing table. |
| Match | The match criteria and patterns associated with this entry. |
| Route To | Destination to which the router will forward a Call; X.25 destinations identify an interface, CMNS destinations identify an interface and host MAC address, XOT destinations identify one (or more) IP addresses. |
You can use the master indexes or search online to find documentation of related commands.
To display information pertaining to the X.25 services, use the show x25 services EXEC command.
show x25 servicesThis command has no arguments and keywords.
EXEC
This command first appeared in Cisco IOS Release 11.2 F.
This command is the default form of the show x25 command.
The following is sample output from the show x25 services command:
Router# show x25 services
X.25 software, Version 3.0.0.
3 configurations supporting 3 active contexts
VCs allocated, freed and in use: 7 - 0 = 7
VCs active and idle: 4, 3
XOT software, Version 2.0.0.
VCs allocated, freed and in use: 2 - 1 = 1
connections in-progress: 0 outgoing and 0 incoming
active VCs: 1, connected to 1 remote hosts
You can use the master indexes or search online to find documentation of related commands.
show x25 interface
show x25 map
show x25 route
show x25 vc
To display information about active switched virtual circuits (SVCs) and permanent virtual circuits (PVCs), use the show x25 vc EXEC command.
show x25 vc [lcn]| lcn | (Optional) Logical channel number (LCN). |
EXEC
This command first appeared prior to Cisco IOS Release 8.3.
To examine a particular virtual circuit number, add an LCN argument to the show x25 vc command.
This command displays information about virtual circuits. Virtual circuits may be used for a number of purposes, such as the following:
The connectivity information displayed will vary according to the traffic carried by the virtual circuit. For multiprotocol circuits, the output varies depending on the number and identity of the protocols mapped to the X.121 address and the encapsulation method selected for the circuit.
The following is sample output from the show x25 vc command used on an encapsulated traffic circuit:
Router# show x25 vc 1024
SVC 1024, State: D1, Interface: Serial0
Started 0:00:31, last input 0:00:31, output 0:00:31
Connects 170090 <-->
compressedtcp 172.20.170.90
ip 172.20.170.90
Call PID multi, Data PID ietf
Reverse charged
Window size input: 2, output: 2
Packet size input: 128, output: 128
PS: 5 PR: 5 ACK: 4 Remote PR: 5 RCNT: 1 RNR: FALSE
Window is closed
P/D state timeouts: 0 Timer (secs): 0
data bytes 505/505 packets 5/5 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0
Table 32 describes the fields shown in the sample output that are typical for virtual circuits.
| Field | Description |
|---|---|
| SVC n or PVC n | Identifies the type of virtual circuit (switched or permanent) and its LCN (also called its "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 International Telecommunication Union Telecommunication Standardization Sector (ITU-T)1 X.25 Recommendation for a description of virtual circuit states. |
| Interface | Interface or subinterface on which the virtual circuit is established. |
| Started | Time elapsed since the virtual circuit was created. |
| last input | Time of last input. |
| output | Shows time of last output. |
| Connects...<-->... | Describes the traffic-specific connection information. See Table 33, Table 34, Table 35 and Table 36 for more information. |
| D-bit permitted | Indicates that the X.25 D-bit (Delivery Confirmation) may be used on this circuit (displayed as needed). |
| Fast select VC | Indicates that the Fast Select facility was present on the incoming call (displayed as needed). |
| Reverse charged | Indicates reverse charged virtual circuit (displayed as needed). |
| Window size | Window sizes for the virtual circuit. |
| Packet size | Maximum packet sizes for the virtual circuit. |
| PS | Current send sequence number. |
| PR | Current receive sequence number. |
| ACK | Last acknowledged incoming packet. |
| Remote PR | Last receive sequence 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 | This line appears if the router cannot transmit any more packets until the X.25 Layer 3 peer has acknowledged some outstanding packets. |
| P/D state timeouts | Number of times a supervisory packet (Reset or Clear) has been retransmitted. |
| Timer | A nonzero time value indicates that a control packet has not been acknowledged yet or that the virtual circuit is being timed for inactivity. |
| Reassembly | Number of bytes received and held for reassembly. Packets with the M-bit set are reassembled into datagrams for encapsulation virtual circuits; switched X.25 traffic is not reassembled (displayed only when values are non-zero). |
| Held Fragments/Packets | Number of X.25 data fragments to transmit to complete an outgoing datagram, and the number of datagram packets waiting for transmission (displayed only when values are non-zero). |
| data bytes m/n packets p/q | Total number of data bytes sent (m), data bytes received (n), data packets sent (p), and data packets received (q) since the circuit was established. |
| Resets t/r | Total number of Reset packets transmitted/received since the circuit was established. |
| RNRs t/r | Total number of Receiver Not Ready packets transmitted/received since the circuit was established. |
| REJs t/r | Total number of Reject packets transmitted/received since the circuit was established. |
| INTs t/r | Total number of Interrupt packets transmitted/received since the circuit was established. |
Table 33 describes the connection fields specific for encapsulation traffic.
| Field | Description |
|---|---|
| 170090 | The X.121 address of the remote host. |
| ip 172.20.170.90 | The higher-level protocol and address values that are mapped to the virtual circuit. |
| Call PID | Identifies the method used for the protocol identification (PID) in the Call User Data (CUD) field. Because PVCs are not set up using a Call packet, this field is not displayed for encapsulation PVCs. The available methods are as follows:
|
|
Data PID | Identifies the method used for protocol identification (PID) when sending datagrams. The available methods are as follows:
|
The following is sample output from the show x25 vc command used on a virtual circuit carrying locally switched X.25 traffic:
Router# show x25 vc
PVC 1, State: D1, Interface: Serial2
Started 0:01:26, last input never, output never
PVC <--> Serial1 PVC 1, connected
Window size input: 2, output: 2
Packet size input: 128, output: 128
PS: 0 PR: 0 ACK: 0 Remote PR: 0 RCNT: 0 RNR: FALSE
P/D state timeouts: 0 Timer (secs): 0
data bytes 0/0 packets 0/0 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0
SVC 5, State: D1, Interface: Serial2
Started 0:00:16, last input 0:00:15, output 0:00:15
Connects 170093 <--> 170090 from Serial1 VC 5
Window size input: 2, output: 2
Packet size input: 128, output: 128
PS: 5 PR: 5 ACK: 4 Remote PR: 5 RCNT: 1 RNR: FALSE
P/D state timeouts: 0 Timer (secs): 0
data bytes 505/505 packets 5/5 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0
Table 34 describes the connection fields for virtual circuits carrying locally switched X.25 traffic.
| Field | Description |
|---|---|
| PVC <--> | Indicates a switched connection between two PVCs. |
| Serial1 PVC 1 | Identifies the other half of a local PVC connection. |
| connected | Identifies connection status for a switched connection between two PVCs. See Table 37 for PVC status messages. |
| 170093 | Identifies the Calling (source) Address of the connection. If a Calling Address Extension was encoded in the call facilities, it is also displayed. If the source host is a CMNS host, its MAC address is also displayed. |
| 170090 | Identifies the Called (destination) Address of the connection. If a Called Address Extension was encoded in the call facilities, it is also displayed. If the destination host is a CMNS host, its MAC address is also displayed. |
| from Serial1 | Indicates the direction of the call and the connecting interface. |
| VC 5 | Identifies the circuit type and LCN for the connecting interface. VC indicates an SVC, and PVC indicates a PVC. If the connecting host is a CMNS host, its MAC address is also displayed. |
The following is sample output from the show x25 vc command used on a virtual circuit carrying locally switched PVC to SVC X.25 traffic:
Router# show x25 vc
PVC 5, State: D1, Interface: Serial0
Started 4d21h, last input 00:00:14, output 00:00:14
Connects 101600 <--> 201700 from Serial2 VC 700
D-bit permitted
Window size input: 2, output: 2
Packet size input: 128, output: 128
PS: 5 PR: 5 ACK: 4 Remote PR: 5 RCNT: 1 RNR: no
P/D state timeouts: 0 timer (secs): 0
data bytes 1000/1000 packets 10/10 Resets 1/0 RNRs 0/0 REJs 0/0 INTs 0/0
SVC 700, State: D1, Interface: Serial2
Started 00:00:16, last input 00:00:16, output 00:00:16
Connects 101600 <--> 201700 from Serial0 PVC 5
Window size input: 2, output: 2
Packet size input: 128, output: 128
PS: 5 PR: 5 ACK: 5 Remote PR: 4 RCNT: 0 RNR: no
P/D state timeouts: 0 timer (secs): 103
data bytes 500/500 packets 5/5 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0
Table 35 describes the connection fields for virtual circuits carrying locally switched X.25 traffic between PVCs and SVCs.
| Field | Description |
|---|---|
| 101600 | Identifies the Calling (source) Address of the connection. If a Calling Address Extension was encoded in the call facilities, it is also displayed. If the source host is a CMNS host, its MAC address is also displayed. |
| 201700 | Identifies the Called (destination) Address of the connection. If a Called Address Extension was encoded in the call facilities, it is also displayed. If the destination host is a CMNS host, its MAC address is also displayed. |
| from Serial2 | Indicates the direction of the call and the connecting interface. |
| VC 700 | Identifies the circuit type and LCN for the connecting interface. VC indicates an SVC and PVC indicates a PVC. If the remote host is a CMNS host, its MAC address is also displayed. |
The following is sample output from the show x25 vc command used on a virtual circuit carrying remotely switched X.25 traffic:
Router# show x25 vc
PVC 2, State: D1, Interface: Serial2
Started 0:01:25, last input never, output never
PVC <--> [172.20.165.92] Serial2/0 PVC 1 connected
XOT between 171.20.165.91, 1998 and 172.20.165.92, 27801
Window size input: 2, output: 2
Packet size input: 128, output: 128
PS: 0 PR: 0 ACK: 0 Remote PR: 0 RCNT: 0 RNR: FALSE
P/D state timeouts: 0 Timer (secs): 0 Reassembly (bytes): 0
Held Fragments/Packets: 0/0
data bytes 0/0 packets 0/0 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0
SVC 6, State: D1, Interface: Serial2
Started 0:00:04, last input 0:00:04, output 0:00:04
Connects 170093 <--> 170090 from
XOT between 172.20.165.91, 1998 and 172.20.165.92, 27896
Window size input: 2, output: 2
Packet size input: 128, output: 128
PS: 5 PR: 5 ACK: 4 Remote PR: 5 RCNT: 1 RNR: FALSE
P/D state timeouts: 0 Timer (secs): 0 Reassembly (bytes): 0
Held Fragments/Packets: 0/0
data bytes 505/505 packets 5/5 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0
Table 36 describes the connection fields for virtual circuits carrying remotely switched X.25 traffic.
| Field | Description |
|---|---|
| PVC | Flags PVC information. |
| [172.20.165.92] | Indicates the IP address of the router remotely connecting the PVC. |
| Serial 2/0 PVC 1 | Identifies the remote interface and PVC number. |
| connected | Identifies connection status for a switched connection between two PVCs. See Table 37 for PVC status messages. |
| 170093 | Identifies the Calling (source) Address of the connection. If a Calling Address Extension was encoded in the call facilities, it is also displayed. |
| 170090 | Identifies the Called (destination) Address of the connection. If a Called Address Extension was encoded in the call facilities, it is also displayed. |
| from | Indicates the direction of the call. |
| XOT between... | Identifies the IP addresses and port numbers of the X.25-over-TCP (XOT) connection. |
Table 37 lists the PVC states that can be reported. These states are also reported by the debug x25 command in PVC-SETUP packets (for remote PVCs only) as well as in the PVCBAD system error message. Some states apply only to remotely switched PVCs.
| Status Message | Description |
|---|---|
| awaiting PVC-SETUP reply | A remote PVC has initiated an XOT TCP connection and is waiting for a reply to the setup message. |
| can't support flow control values | The window sizes or packet sizes of the PVC cannot be supported by one of its two interfaces. |
| connected | The PVC is up. |
| dest. disconnected | The other end disconnected the PVC. |
| dest interface is not up | The target interface's X.25 service is down. |
| dest PVC config mismatch | The targeted PVC is already connected. |
| mismatched flow control values | The configured flow control values do not match. |
| no such dest. interface | The remote destination interface was reported to be in error by the remote router. |
| no such dest. PVC | The targeted PVC does not exist. |
| non-X.25 dest. interface | The target interface is not configured for X.25. |
| PVC/TCP connect timed out | A remote PVC XOT TCP connection attempt timed out. |
| PVC/TCP connection refused | A remote PVC XOT TCP connection was tried and refused. |
| PVC/TCP routing error | A remote PVC XOT TCP connection routing error was reported. |
| trying to connect via TCP | A remote PVC XOT TCP connection is established and is in the process of connecting. |
| waiting to connect | The PVC is waiting to be processed for connecting. |
To display information for all XOT virtual circuits that match a given criterion, use the show x25 xot EXEC command.
show x25 xot [local ip-address [port port]] [remote ip-address [port port]]| local ip-address [port port] | Local IP address and optional port number. |
| remote ip-address [port port] | Remote IP address and optional port number. |
EXEC
This command first appeared in Cisco IOS Release 11.2 F.
The following show x25 xot sample output displays information about all XOT virtual circuits:
Router> show x25 xot
SVC 11, State: D1, Interface: [2.2.2.2,1998/2.2.2.1,11002]
Started 00:00:08, last input 00:00:08, output 00:00:08
Line: 0 con 0 Location: Host: 5678
111 connected to 5678 PAD <--> XOT 2.2.2.2,1998
Window size input: 2, output: 2
Packet size input: 128, output: 128
PS: 2 PR: 3 ACK: 3 Remote PR: 2 RCNT: 0 RNR: no
P/D state timeouts: 0 timer (secs): 0
data bytes 54/18 packets 2/3 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0
You can use the master indexes or search online to find documentation of related commands.
show x25 interface
show x25 services
To configure the Cisco IOS software to accept all reverse charge calls, use the x25 accept-reverse interface configuration command. To disable this facility, use the no form of this command.
x25 accept-reverseThis command has no arguments or keywords.
Disabled
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
This command causes the interface to accept reverse charge calls by default. You can also configure this behavior for each peer with the x25 map interface configuration command.
The following example sets acceptance of reverse charge calls:
interface serial 0
x25 accept-reverse
You can use the master indexes or search online to find documentation of related commands.
| x121-address | Variable-length X.121 address. The address is assigned by the X.25 network service provider. |
DDN and BFE encapsulations have a default interface address generated from the interface IP address; for proper DDN or BFE operation, this generated X.121 address must not be changed. Standard X.25 encapsulations do not have a default.
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
When you are connecting to a public data network (PDN), the PDN administrator will assign the X.121 address to be used. Other applications (for example, a private X.25 service), may assign arbitrary X.121 addresses as required by the network and service design. X.25 interfaces that engage in X.25 switching only do not need to assign an X.121 address.
The following example sets the X.121 address for the interface:
interface serial 0
encapsulation x25
x25 address 00000123005
The address must match that assigned by the X.25 network service provider.
| destination-pattern | Regular expression used to match against the destination address of a received call. |
| cud cud-pattern | (Optional) Call user data (CUD) pattern, a regular expression of ASCII text. The CUD field might be present in a call packet. The first few bytes (commonly 4 bytes long) identify a protocol; the specified pattern is applied to any user data after the protocol identification. |
No alias is configured.
Interface configuration
This command first appeared in Cisco IOS Release 11.2 F. It replaces the functionality that was provided by the alias keyword of the x25 route command.
Encapsulation, PAD, and QLLC calls are normally accepted when the destination address is that of the interface (or the zero-length address). Those calls will also be accepted when the destination address matches a configured alias.
An X.25 call may be addressed to the receiving interface; calls addressed to the receiving interface are eligible for acceptance as a datagram encapsulation, PAD or QLLC connection, and may not be routed. In the following example, serial interface 0 is configured with a native address of 0000123 and a destination alias for any address that starts with 1111123. That is, serial interface 0 can accept its own calls and calls for any destination that starts with 1111123.
interface serial 0
encapsulation x25
x25 address 0000123
x25 alias ^1111123.*
To specify how a router configured for x25 bfe-emergency decision will participate in emergency mode, use the x25 bfe-decision interface configuration command.
x25 bfe-decision {no | yes | ask}| no | Prevents the router from participating in emergency mode and from sending address translation information to the BFE device. |
| yes | Allows the router to participate in emergency mode and to send address translation information to the BFE when the BFE enters emergency mode. This information is obtained from the table created by the x25 remote-red command. |
| ask | Configures the Cisco IOS software to prompt you to enter the bfe EXEC command. |
The router does not participate in emergency mode.
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
The following example configures serial interface 0 to require an EXEC command from you 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 Cisco IOS software prompts you for the EXEC command bfe enter to direct the router 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
You can use the master indexes or search online to find documentation of related commands.
bfe
x25 bfe-emergency
x25 remote-red
To configure the circumstances under which the router participates in emergency mode, use the x25 bfe-emergency interface configuration command.
x25 bfe-emergency {never | always | decision}| never | Prevents the router from sending address translation information to the Blacker Front End (BFE). If it does not receive address translation information, the BFE cannot open a new connection for which it does not know the address. |
| always | Allows the router to pass address translations to the BFE when it enters emergency mode and an address translation table has been created. |
| decision | Directs the router to wait until it receives a diagnostic packet from the BFE device indicating that the emergency mode window is open. The window is only open when a condition exists that allows the BFE to enter emergency mode. When the diagnostic packet is received, the participation in emergency mode depends on how the router is configured with the x25 bfe-decision command. |
No address translation information is sent to the BFE.
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
The following example configures serial interface 0 to require an EXEC command from you 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 Cisco IOS software prompts you for the EXEC command bfe enter to direct the router 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
| protocol | Specifies the protocol to assume; may be ip or pad. |
No default protocol is set.
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
This command specifies the protocol assumed by the Cisco IOS software for incoming calls with unknown or missing protocol identifier in the call user data (CUD). If you do not use the x25 default interface configuration command, the software clears any incoming calls with unrecognized CUD.
The following example establishes IP as the default protocol for X.25 calls:
interface serial 0
x25 default ip
You can use the master indexes or search online to find documentation of related commands.
To force facilities on a per-call basis for calls originated by the router (switched calls are not affected), use the x25 facility interface configuration command. To disable a facility, use the no form of this command.
x25 facility facility-keyword value| facility-keyword | User facility. |
| value | Facility value; see Table 38 for a list of supported facilities and their values. |
No facility is sent.
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
Table 38 lists X.25 user facilities.
The following example specifies a transit delay value in an X.25 configuration:
interface serial 0
x25 facility transit-delay 24000
The following example sets an ROA name and then sends the list via the X.25 user facilities:
x25 roa green_list 23 35 36
interface serial 0
x25 facility roa green_list
You can use the master indexes or search online to find documentation of related commands.
To set the highest incoming-only virtual circuit number, use the x25 hic interface configuration command.
x25 hic circuit-number| circuit-number | Virtual circuit number from 1 to 4095, or 0 if there is no incoming-only virtual circuit range. The default is 0. |
0
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
This command is applicable only if you have the X.25 switch configured for an incoming-only virtual circuit range. Incoming is from the perspective of the X.25 DTE. If you do not want any outgoing calls from your DTE, configure both ends to disable the two-way range (set the values of x25 ltc and x25 htc to 0) and configure an incoming-only range. Any incoming-only range must come before (that is, must be numerically less than) any two-way range. Any two-way range must come before any outgoing-only range.
The following example sets a valid incoming-only virtual circuit range of 1 to 5:
interface serial 0
x25 lic 1
x25 hic 5
You can use the master indexes or search online to find documentation of related commands.
To set the highest outgoing-only virtual circuit number, use the x25 hoc interface configuration command.
x25 hoc circuit-number| circuit-number | Virtual circuit number from 1 to 4095, or 0 if there is no outgoing-only virtual circuit range. The default is 0. |
0
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
This command is applicable only if you have the X.25 switch configured for an outgoing-only virtual circuit range. Outgoing is from the perspective of the X.25 DTE. If you do not want any incoming calls on your DTE, disable the two-way range (set the values of x25 ltc and x25 htc to 0) and configure an outgoing-only range. Any outgoing-only range must come after (that is, be numerically greater than) any other range.
The following example sets a valid outgoing-only virtual circuit range of 2000 to 2005:
interface serial 0
x25 loc 2000
x25 hoc 2005
You can use the master indexes or search online to find documentation of related commands.
To set the maximum number of packets to hold until a virtual circuit is able to transmit, use the x25 hold-queue interface configuration command. To remove this command from the configuration file and restore the default value, use the no form of this command without an argument.
x25 hold-queue packets| packets | Number of packets. 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. The default is 10 packets. |
10 packets
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
If you set the queue-size to 0 when using the no x25 hold-queue command, there will be no hold queue limit. While this setting will prevent drops until the router runs out of memory, it is only rarely appropriate. A virtual circuit hold queue value is determined when it is created; changing this parameter will not affect the hold queue limits of the existing virtual circuits.
The following example sets the X.25 hold queue to hold 25 packets:
interface serial 0
x25 hold-queue 25
You can use the master indexes or search online to find documentation of related commands.
To start the timer that prevents additional calls to a destination for a given period of time (thus preventing overruns on some X.25 switches caused by Call Request packets), use the x25 hold-vc-timer interface configuration command. To restore the default value for the timer, use the no form of this command.
x25 hold-vc-timer minutes| minutes | Number of minutes to prevent calls from going to a previously failed destination. Incoming calls are still accepted. The default is 0 minutes. |
0 minutes
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
Only Call Requests that the router originates are 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 sets this timer to 3 minutes:
interface serial 0
x25 hold-vc-timer 3
| name | Host name. |
| x121-address | The X.121 address. |
| cud call-user-data | (Optional) Sets the Call User Data (CUD) field in the X.25 Call Request packet. |
No static host name-to-address mapping is defined.
Global configuration
This command first appeared prior to Cisco IOS Release 10.0.
The following example specifies a static address mapping:
x25 host Willard 4085551212
The following example removes a static address mapping:
no x25 host Willard
To set the highest two-way virtual circuit number, use the x25 htc interface configuration command.
x25 htc circuit-number| circuit-number | Virtual circuit number from 1 to 4095, or 0 if there is no two-way virtual circuit range. The default is 1024 for X.25 network service interfaces; 4095 for CMNS network service interfaces. |
1024 for X.25 network service interfaces; 4095 for CMNS network service interfaces.
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
This command is applicable if the X.25 switch is configured for a two-way virtual circuit range. Any two-way virtual circuit range must come after (that is, be numerically larger than) any incoming-only range, and must come before any outgoing-only range.
The following example sets a valid two-way virtual circuit range of 5 to 25:
interface serial 0
x25 ltc 5
x25 htc 25
You can use the master indexes or search online to find documentation of related commands.
To define the period of inactivity after which the router can clear a switched virtual circuit (SVC), use the x25 idle interface configuration command.
x25 idle minutes| minutes | Idle period in minutes. The default is 0, which causes the router to keep the SVC open indefinitely. |
0 (the SVC is kept open indefinitely)
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
Calls originated and terminated by the router are cleared; PAD and switched virtual circuits are not affected. To clear one or all virtual circuits at once, use the privileged EXEC command clear x25.
The following example sets a 5-minute wait period before an idle circuit is cleared:
interface serial 2
x25 idle 5
You can use the master indexes or search online to find documentation of related commands.
This command has no arguments or keywords.
The router opens one virtual circuit for all types of service.
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
This feature is useful only for DDN or BFE encapsulations, because only these methods have an IP precedence facility defined to allow the source and destination devices to both use the virtual circuit for traffic of the given IP priority.
Verify that your host does not send nonstandard data in the IP type of service (TOS) field because it can cause multiple wasteful virtual circuits to be created.
Four virtual circuits may be opened based on IP precedence to encapsulate routine, priority, immediate, and all higher precedences.
The x25 map nvc limit or the default x25 nvc limit still applies.
The following example allows new IP encapsulation virtual circuits based on the IP precedence:
interface serial 3
x25 ip-precedence
To set the interface default maximum input packet size to match that of the network, use the x25 ips interface configuration command.
x25 ips bytes| bytes | Byte count. It can be one of the following values: 16, 32, 64, 128, 256, 512, 1024, 2048, or 4096. The default is 128 bytes. |
128 bytes
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
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, the Cisco IOS software must break the packet into two or more X.25 packets with the more data bit (M-bit) set. The receiving device collects all packets with the M-bit set and reassembles the original packet.
The following example sets the default maximum packet sizes to 512:
interface serial 1
x25 ips 512
x25 ops 512
You can use the master indexes or search online to find documentation of related commands.
To set the lowest incoming-only virtual circuit number, use the x25 lic interface configuration command.
x25 lic circuit-number| circuit-number | Virtual circuit number from 1 to 4095, or 0 if there is no incoming-only virtual circuit range. |
0
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
This command is applicable only if you have the X.25 switch configured for an incoming-only virtual circuit range. Outgoing is from the perspective of the X.25 DTE. If you do not want any incoming calls on your DTE, disable the two-way range (set the values of x25 ltc and x25 htc to 0) and configure an outgoing-only range. Any outgoing-only range must come after (that is, be numerically greater than) any other range.
This command is applicable if you have the X.25 switch configured for two-way virtual circuit range.
The following example sets a valid incoming-only virtual circuit range of 1 to 5 and sets the lowest two-way virtual circuit number:
interface serial 0
x25 lic 1
x25 hic 5
x25 ltc 6
You can use the master indexes or search online to find documentation of related commands.
This command has no arguments or keywords.
Forcing packet-level restarts is the default and is necessary for networks that expect this behavior.
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
The following example disables the link-level restart:
interface serial 3
no x25 linkrestart
| circuit-number | Virtual circuit number from 1 to 4095, or 0 if there is no outgoing-only virtual circuit range. The default is 0. |
0
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
This command is applicable only if you have the X.25 switch configured for an outgoing-only virtual circuit range. Outgoing is from the perspective of the X.25 DTE. If you do not want any incoming calls from your DTE, configure the values of x25 loc and x25 hoc and set the values of x25 ltc and x25 htc to 0.
The following example sets a valid outgoing-only virtual circuit range of 2000 to 2005:
interface serial 0
x25 loc 2000
x25 hoc 2005
You can use the master indexes or search online to find documentation of related commands.
To set the lowest two-way virtual circuit number, use the x25 ltc interface configuration command.
x25 ltc circuit-number| circuit-number | Virtual circuit number from 1 to 4095, or 0 if there is no two-way virtual circuit range. The default is 1. |
1
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
This command is applicable if you have the X.25 switch configured for a two-way virtual circuit range. Any two-way virtual circuit range must come after (that is, be numerically larger than) any incoming-only range, and must come before any outgoing-only range.
The following example sets a valid two-way virtual circuit range of 5 to 25:
interface serial 0
x25 ltc 5
x25 htc 25
You can use the master indexes or search online to find documentation of related commands.
To set up the LAN protocols-to-remote host mapping, use the x25 map interface configuration command. To retract a prior mapping, use the no form of this command with the appropriate network protocol(s) and X.121 address argument.
x25 map protocol address [protocol2 address2[...[protocol9 address9]]] x121-address [option]| protocol | Protocol type, entered by keyword. Supported protocols are entered by keyword, as listed in Table 39. As many as nine protocol and address pairs can be specified in one command line. |
| address | Protocol address. |
| x121-address | X.121 address of the remote host. |
| option | (Optional) Additional functionality that can be specified for originated calls. Can be any of the options listed in Table 40. |
No LAN protocol-to-remote host mapping is set up.
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
Because no defined protocol can dynamically determine LAN protocol-to-remote host mappings, you must enter all the information for each host with which the router may exchange X.25 encapsulation traffic.
Two methods are available to encapsulate traffic, Cisco's long-available encapsulation method and the IETF's standard method (defined in RFC 1356); the latter allows hosts to exchange several protocols over a single virtual circuit. Cisco's encapsulation method is the default (for backward compatibility) unless the interface configuration command specifies ietf.
When you configure multiprotocol maps, you can specify a maximum of nine protocol and address pairs in an x25 map command. However, you can specify a protocol only once. For example, you can specify the IP protocol and an IP address, but you cannot specify another IP address. If compressedtcp and ip are both specified, the same IP address must be used.
Bridging is supported only if you are using Cisco's traditional encapsulation method. For correct operation, bridging maps must specify the broadcast option.
Since most datagram routing protocols rely on broadcasts or multicasts to send routing information to their neighbors, the broadcast keyword is needed to run such routing protocols over X.25.
Encapsulation maps might also specify that traffic between the two hosts should be compressed, thus increasing the effective bandwidth between them at the expense of memory and computation time. Because each compression virtual circuit requires memory and computation resources, compression must be used with care and monitored to maintain acceptable resource usage and overall performance.
OSPF treats a nonbroadcast, multiaccess network such as X.25 in much the same way as it treats a broadcast network by requiring the selection of a designated router. In previous releases, this required manual assignment in the OSPF configuration using the neighbor router configuration command. When the x25 map command is included in the configuration with the broadcast, and the ip ospf network command (with the broadcast keyword) is configured, there is no need to configure any neighbors manually. OSPF will now run over the X.25 network as a broadcast network. (Refer to the ip ospf network interface configuration command for more detail.)
You can modify the options of an x25 map command by restating the complete set of protocols and addresses specified for the map, followed by the desired options. To delete a map command, you must also specify the complete set of protocols and addresses; the options can be omitted when deleting a map.
Once defined, a map's protocols and addresses cannot be changed. This requirement exists because the Cisco IOS software cannot determine whether you want to add to, delete from, or modify an existing map's protocol and address specification, or simply mistyped the command. To change a map's protocol and address specification, you must delete it and create a new map.
A given protocol-address pair cannot be used in more than one map on the same interface.
Table 39 lists the protocols supported by X.25.
| Keyword | Protocol |
|---|---|
| apollo | Apollo Domain |
| appletalk | AppleTalk |
| bridge | Bridging1 |
| clns | ISO Connectionless Network Service |
| compressedtcp | TCP/IP header compression |
| decnet | DECnet |
| ip | IP |
| ipx | Novell IPX |
| pad | PAD links2 |
| qllc | System Network Architecture (SNA) encapsulation in X.253 |
| vines | Banyan VINES |
| xns | XNS |
The CMNS map form is obsolete; its function is replaced by the enhanced x25 route command.
Table 40 lists the map options supported by X.25.
The following example maps IP address 172.20.2.5 to X.121 address 000000010300. The broadcast keyword directs any broadcasts sent through this interface to the specified X.121 address.
interface serial 0
x25 map ip 171.20.2.5 000000010300 broadcast
The following example specifies an ROA name to be used for originating connections:
x25 roa green_list 23 35 36
interface serial 0
x25 map ip 172.20.170.26 10 roa green_list
The following example specifies a network user ID (NUID) facility to send on calls originated for the address map:
interface serial 0
x25 map ip 172.20.174.32 2 nudata "Network User ID 35"
Strings can be quoted, but quotation marks are not required unless embedded blanks are present.
You can use the master indexes or search online to find documentation of related commands.
ip ospf network
show x25 map
x25 facility
x25 map bridge
x25 map compressedtcp
x25 map pad
x25 route
x25 roa
To configure an Internet-to-X.121 address mapping for bridging over X.25, use the x25 map bridge interface configuration command.
x25 map bridge x121-address broadcast [option]| x121-address | The X.121 address. |
| broadcast | Required keyword for bridging over X.25. |
| option | (Optional) Services that can be added to this map; the same options as the x25 map command; see Table 40 earlier in this chapter. |
No bridging over X.25 is configured.
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
The following example configures transparent bridging over X.25 between two Cisco routers using a maximum of six virtual circuits:
interface serial 1
x25 map bridge 000000010300 broadcast nvc 6
You can use the master indexes or search online to find documentation of related commands.
The enhanced x25 route command replaces the x25 map cmns command. Refer to the description of the x25 route command for more information.
To map compressed TCP traffic to an X.121 address, use the x25 map compressedtcp interface configuration command. To delete a TCP/IP header compression map for the link, use the no form of this command.
x25 map compressedtcp ip-address [protocol2 address2 [...[protocol9 address9]]]| ip-address | IP address. |
| protocol | (Optional) Protocol type, entered by keyword. Supported protocols are entered by keyword, as listed in Table 39. As many as nine protocol and address pairs can be specified in one command line. |
| address | (Optional) Protocol address. |
| x121-address | X.121 address. |
| option | (Optional) The same options as those for the x25 map command; see Table 40 earlier in this chapter. |
No mapping is configured.
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
Cisco supports RFC 1144 TCP/IP header compression (THC) on serial lines using HDLC and X.25 encapsulation. THC encapsulation is only slightly different from other encapsulation traffic, but these differences are worth noting. The implementation of compressed TCP over X.25 uses one virtual circuit to pass the compressed packets. Any IP traffic (including standard TCP) is separate from TCH traffic; it is carried over separate IP encapsulation virtual circuits or identified separately in a multiprotocol virtual circuit.
The nvc map option cannot be used for TCP/IP header compression, because only one virtual circuit can carry compressed TCP/IP header traffic to a given host.
The following example establishes a map for TCP/IP header compression on serial interface 4:
interface serial 4
ip tcp header-compression
x25 map compressedtcp 172.20.2.5 000000010300
You can use the master indexes or search online to find documentation of related commands.
To configure an X.121 address mapping for packet assembler/disassembler (PAD) access over X.25, use the x25 map pad interface configuration command.
x25 map pad x121-address [option]| x121-address | X.121 address of the interface. |
| option | (Optional) Services that can be added to this map--the same options as the x25 map command (see Table 40 earlier in this chapter). |
No specific options are used for PAD access.
Interface configuration
This command first appeared in Cisco IOS Release 10.2.
Use a PAD map to configure optional X.25 facility use for PAD access. When used with the x25 pad-access interface configuration command, the x25 map pad command restricts incoming PAD access to those statically mapped hosts.
The following example configures an X.25 interface to restrict incoming PAD access to the single mapped host. This example requires that both incoming and outgoing PAD access use the network user identification (NUID) user authentication.
interface serial 1
x25 pad-access
x25 map pad 000000010300 nuid johndoe secret
You can use the master indexes or search online to find documentation of related commands.
To set the window modulus, use the x25 modulo interface configuration command.
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. The default is 8. |
8
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
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. Modulo 128 operation is also referred to as extended packet sequence numbering, which allows larger packet windows.
The following example sets the window modulus to 128:
interface serial 0
x25 modulo 128
You can use the master indexes or search online to find documentation of related commands.
| count | Circuit count from 1 to 8. A maximum of eight virtual circuits can be configured for each protocol-host pair. Protocols that do not tolerate out-of-order delivery, such as encapsulated TCP/IP header compression, will use only one virtual circuit despite this value. The default is 1. Permitting more than one VC may help throughput on slow networks. |
1
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
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 sets the default maximum number of VCs that each map can have open simultaneously to 4:
interface serial 0
x25 nvc 4
To set the interface default maximum output packet size to match that of the network, use the x25 ops interface configuration command.
x25 ops bytes| bytes | Byte count that is one of the following: 16, 32, 64, 128, 256, 512, 1024, 2048, or 4096. The default is 128 bytes. |
128 bytes
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
X.25 networks use maximum output packet sizes set by the network administrator. 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, the Cisco IOS software must break the packet into two or more X.25 packets with the more data bit (M-bit) set. The receiving device collects all packets with the M-bit set and reassembles the original packet.
The following example sets the default maximum packet sizes to 512:
interface serial 1
x25 ips 512
x25 ops 512
You can use the master indexes or search online to find documentation of related commands.
Use the x25 pad-access interface configuration command to cause the packet assembler/disassembler (PAD) software to accept PAD connections only from statically mapped X.25 hosts. To disable checking maps on PAD connections, use the no form of this command.
x25 pad-accessThis command has no arguments or keywords.
Accept PAD connections from any host.
Interface configuration
This command first appeared in Cisco IOS Release 10.2.
By default, all PAD connection attempts are processed for session creation or protocol translation, subject to the configuration of those functions. If you use the x25 pad-access command, PAD connections are processed only for incoming calls with a source address that matches a statically mapped address configured with the x25 map pad interface configuration command. PAD connections are refused for any incoming calls with a source address that has not been statically mapped.
The following example restricts incoming PAD access on the interface to attempts from the host with the X.121 address 000000010300:
interface serial 1
x25 pad-access
x25 map pad 000000010300
You can use the master indexes or search online to find documentation of related commands.
service pad
x25 map pad
x29 access-list
x29 profile
To establish an encapsulation permanent virtual circuit (PVC), use the encapsulating version of the x25 pvc interface configuration command. To delete the PVC, use the no form of this command with the appropriate channel number.
x25 pvc circuit protocol address [protocol2 address2[...[protocol9 address9]]] x121-address| circuit | Virtual-circuit channel number, which must be less than the virtual circuits assigned to the switched virtual circuits (SVCs). |
| protocol | Protocol type, entered by keyword. Supported protocols are listed in Table 41. As many as nine protocol and address pairs can be specified in one command line. |
| address | Protocol address of the host at the other end of the PVC. |
| x121-address | X.121 address. |
| option | (Optional) Provides additional functionality or allows X.25 parameters to be specified for the PVC. Can be any of the options listed in Table 42. |
No encapsulation PVC is established. The PVC window and maximum packet sizes default to the interface default values.
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
PVCs are not supported for ISO CMNS.
You no longer need to specify a datagram protocol-to-address mapping before you can set up a PVC; a map is implied from the PVC configuration. Configurations generated by the router will no longer specify a map for encapsulating PVCs.
When configuring a PVC to carry CLNS traffic, use the X.121 address as the subnetwork point of attachment (SNPA) to associate the PVC with a CLNS neighbor configuration. When configuring a PVC to carry transparent bridge traffic, the X.121 address is required to identify the remote host to the bridging function. Other encapsulation PVCs do not require an X.121 address.
Table 41 lists supported protocols.
| Keyword | Protocol |
|---|---|
| apollo | Apollo Domain |
| appletalk | AppleTalk |
| bridge | Bridging1 |
| clns | OSI Connectionless Network Service |
| compressedtcp | TCP/IP header compression |
| decnet | DECnet |
| ip | IP |
| ipx | Novell IPX |
| qllc | SNA encapsulation in X.252 |
| vines | Banyan VINES |
| xns | XNS |
Table 42 lists supported X.25 PVC options.
The following example establishes a PVC on channel 2 to encapsulate VINES and IP with the far host:
interface serial 0
x25 ltc 5
x25 pvc 2 vines 60002A2D:0001 ip 172.20.170.91 11110001
You can use the master indexes or search online to find documentation of related commands.
To configure a switched permanent virtual circuit (PVC) for a given interface, use the switched version of the x25 pvc interface configuration command.
x25 pvc number1 interface type number pvc number2 [option]| number1 | PVC number that will be used on the local interface (as defined by the primary interface command). |
| interface | Required keyword to specify an interface. |
| type | Remote interface type. |
| number | Remote interface number. |
| pvc | Required keyword to specify a switched PVC. |
| number2 | PVC number that will be used on the remote interface. |
| option | (Optional) Adds certain features to the mapping specified; can be either option listed in Table 43. |
No switched PVC is configured. The PVC window and maximum packet sizes default to the interface default values.
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
You can configure X.25 PVCs in the X.25 switching software. As a result, DTEs that require permanent circuits can be connected to the router acting as an X.25 switch and have a properly functioning connection. X.25 resets will be sent to indicate when the circuit comes up or goes down.
PVC circuit numbers must come before (that is, be numerically smaller than) the circuit numbers allocated to any SVC range.
Table 43 lists the switched PVC options supported by X.25.
The following example configures a PVC connected between two serial interfaces on the same router. In this type of interconnection configuration, the alternate interface must be specified along with the PVC number on that interface. To make a working PVC connection, two commands must be specified, each pointing to the other, as this example illustrates.
interface serial 0
encapsulation x25
x25 ltc 5
x25 pvc 1 interface serial 1 pvc 1
interface serial 1
encapsulation x25
x25 ltc 5
x25 pvc 1 interface serial 0 pvc 1
To configure a switched PVC to SVC circuit for a given interface, use the switched version of the x25 pvc interface configuration command.
x25 pvc number1 svc x121-address [flow-control-options] [call-control-options]| number1 | Logical channel ID of the PVC. Value must be lower than any range of circuit numbers defined for SVCs. |
| svc | Specifies a switched virtual circuit type. |
| x121-address | Destination X.121 address for opening an outbound switched virtual circuit and source X.121 address for matching an inbound switched virtual circuit. |
| flow-control-options | (Optional) Adds certain features to the mapping specified; can be any of the options listed in Table 44. |
| call-control-options | (Optional) Adds certain features to the mapping specified; can be any of the options listed in Table 45. |
No switched PVC is configured. The PVC window and maximum packet sizes default to the interface default values.
The default idle time comes from the interface on which the x25 pvc command is configured, not the interface on which the call is sent/received.
Interface configuration
This command first appeared in Cisco IOS Release 11.2 F.
PVC circuit numbers must come before (that is, be numerically smaller than) the circuit numbers allocated to any SVC range.
On an outgoing call, the packet size facilities and window size facilities will be included. The call will be cleared if the call accepted packet specifies different values.
On an incoming call, requested values that do not match the configured values will be refused.
Table 44 lists the flow control options supported by X.25 during PVC to SVC switching.
| Option | Description |
|---|---|
| packetsize in-size out-size | Maximum input packet size (in-size) and output packet size (out-size) for both the PVC and SVC. Values may differ but must be one of the following: 16, 32, 64, 128, 256, 512, 1024, 2048, or 4096. |
| windowsize in-size out-size | Packet count for input window (in-size) and output window (out-size) for both the PVC and SVC. Both values may differ but must be in the range 1 to 127 and must be less than the value set for the x25 modulo command. |
Table 45 lists the call control options supported by X.25 during PVC to SVC switching.
| Option | Description |
|---|---|
| idle minutes | Idle time-out for the SVC. This option will override the interface's x25 idle command value only for this circuit. |
| no-incoming | Establishes a switched virtual circuit to the specified X.121 address when data is received from the permanent virtual circuit, but does not accept calls from this X.121 address. |
| no-outgoing | Accepts an incoming call from the specified X.121 address, but does not attempt to place a call when data is received from the permanent virtual circuit. If data is received from the permanent virtual circuit while no call is connected, the PVC will be reset. |
| accept-reverse | Causes the Cisco IOS software to accept incoming reverse-charged calls. If this option is not present, the Cisco IOS software clears reverse-charged calls unless the interface accepts all reverse-charged calls. |
The following example configures PVC to SVC switching between two serial interfaces:
x25 routing
interface serial0
encapsulation x25
x25 address 201700
x25 ltc 128
x25 idle 2
interface serial2
encapsulation x25 dce
x25 address 101702
x25 route ^20 interface serial0
x25 route ^10 interface serial2
interface serial0
x25 pvc 5 svc 101601 packetsize 128 128 windowsize 2 2 no-incoming
x25 pvc 6 svc 101602 packetsize 128 128 windowsize 2 2 no-outgoing idle 0
x25 pvc 7 svc 101603 packetsize 128 128 windowsize 2 2
Any call with a destination address beginning with 20 will be routed to serial interface 0. Any call with a destination address beginning with 10 will be routed to serial interface 2. (Note that incoming calls will not be routed back to the same interface from which they arrived.)
Traffic received on PVC 5 on serial interface 0 will cause a call to be placed from address 201700 to the X.121 address 101601. The routing table will then forward the call to serial interface 2. If no data is sent or received on the circuit for two minutes, the call will be cleared, as defined by the x25 idle command. All incoming calls from 101601 to 201700 will be refused, as defined by the no-incoming attribute.
The second x25 pvc command configures the circuit to allow incoming calls from 101602 to 201700 to be connected to PVC 6 on serial interface 1. Because idle is set to 0, the call will remain connected until cleared by the remote host or an X.25 restart. Because outgoing calls are not permitted for this connection, if traffic is received on PVC 6 on serial interface 0 before the call is established, the traffic will be discarded and the PVC will be reset.
The last x25 pvc command configures the circuit to accept an incoming call from 101603 to 201700 and connects the call to PVC 7 on serial interface 0. If no data is sent or received on the circuit for two minutes, the call will be cleared. If traffic is received on PVC 7 on serial interface 0 before the call is established, a call will be placed to 101503 to 201700.
| number1 | PVC number of the connecting device. |
| xot | Indicates two PVCs will be connected across a TCP/IP LAN using XOT. |
| address | IP address of the device to which you are connecting. |
| interface serial | Indicates the interface is serial. |
| string | Serial interface specification that accepts either a number or a string in model 7000 format (number/number) to denote the serial interface. |
| pvc | Indicates a PVC. |
| number2 | Remote PVC number on the target interface. |
| option | (Optional) Adds certain features for the connection; can be either option listed in Table 46. |
No PVCs are connected across a TCP/IP LAN. The PVC window and packet sizes default to the interface default values.
Interface configuration
This command first appeared in Cisco IOS Release 10.3.
Use the PVC tunnel commands to tell the Cisco IOS software what the far end of the PVC is connected to. The incoming and outgoing packet sizes and window sizes must match the remote PVC outgoing and incoming sizes.
Each X.25-over-TCP (XOT) connection relies on a TCP session to carry traffic. To ensure that these TCP sessions remain connected in the absence of XOT traffic, use the service tcp-keepalives-in and service tcp-keepalives-out global configuration commands. If TCP keepalives are not enabled, XOT permanent virtual circuits (PVCs) might encounter problems if one end of the connection is reloaded. When the reloaded host attempts to establish a new connection, the other host refuses the new connection because it has not been informed that the old session is no longer active. Recovery from this state requires the other host to be informed that its TCP session is no longer viable so that it attempts to reconnect the PVC.
Also, TCP keepalives inform a router when an XOT switched virtual circuit (SVC) session is not active, thus freeing the router's resources.
Table 46 lists the PVC tunnel options supported by X.25.
The following example enters the parameters for one side of a connection destined for a platform other than the Cisco 7000 series with RSP7000:
service tcp-keepalives-in
service tcp-keepalives-out
interface serial 0
x25 pvc 1 xot 172.20.1.2 interface serial 1 pvc 2
The following example enters the parameters for one side of a connection destined for the Cisco 7000 series with RSP7000:
service tcp-keepalives-in
service tcp-keepalives-out
interface serial 0
x25 pvc 1 xot 172.20.1.2 interface serial 1/1 pvc 2
See the section "X.25 and LAPB Configuration Examples" in the Wide-Area Networking Configuration Guide for more complete configuration examples.
You can use the master indexes or search online to find documentation of related commands.
service tcp-keepalives-in
service tcp-keepalives-out
To set up the table that lists the Blacker Front End (BFE) nodes (host or gateways) to which the router will send packets, use the x25 remote-red interface configuration command.
x25 remote-red host-ip-address remote-black blacker-ip-address| host-ip-address | IP address of the host or router 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. |
No table is set up.
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
The table that results from this command provides the address translation information the router sends to the BFE when it is in emergency mode.
The following example sets up a short table of BFE nodes for serial interface 0:
interface serial 0
x25 remote-red 172.20.9.3 remote-black 172.20.9.13
x25 remote-red 192.108.15.1 remote-black 192.108.15.26
You can use the master indexes or search online to find documentation of related commands.
show x25 remote-red
x25 bfe-decision
To create an entry in the X.25 routing table (to be consulted for forwarding incoming calls and for placing outgoing PAD or protocol translation calls), use an appropriate form of the x25 route global configuration command. To remove an entry from the table, use the no form of the command.
x25 route [#position] {[selection] [modification]} disposition [xot-keepalive]| #position | (Optional) A pound sign (#) followed by a number designates the position in the routing table at which to insert the new entry. If no position value is given, the entry is appended to the end of the routing table. |
| selection | (Optional) The selection options identify when the subsequent modification and disposition elements apply to an X.25 call; any or all variables may be specified for a route. See Table 47 in the "Usage Guidelines" section for the valid selection keyword and argument options.
Although each individual selection criterion is optional, at least one selection or modification element must be specified in the x25 route command. |
| modification | (Optional) Modifies the source or destination addresses of the selected calls. The standard regular expression substitution rules are used, where a match pattern and rewrite string direct the construction of a new string. See Table 48 in the "Usage Guidelines" section for the valid modification keyword and argument options.
Although each individual modification is optional, at least one selection or modification element must be specified in the x25 route command. |
| disposition | Specifies the disposition of a call matching the specified selection pattern. See Table 52 in the "Usage Guidelines" section for the valid disposition keyword and argument options. |
| xot-keepalive | (Optional) Specifies an XOT keepalive period and number of XOT keepalive retries. XOT relies on TCP to detect when the underlying connection is dead. TCP detects a dead connection when transmitted data goes unacknowledged for a given number of attempts over a period of time. See Table 53 in the "Usage Guidelines" section for keepalive options. |
No entry is created in the X.25 routing table.
Global configuration
The enhanced x25 route command replaces the x25 map cmns command. The x25 route alias form of this command (supported in earlier releases) has been replaced by the x25 alias command.
The selection criteria source and dest-ext first appeared in Cisco IOS Release 11.2 F. The interface disposition to a CMNS destination first appeared in Cisco IOS Release 11.2 F; in prior releases, CMNS routing information was implied by maps defining an NSAP prefix for a CMNS host's MAC address. The clear interface disposition first appeared in Cisco IOS Release 11.2 F; in prior releases, the disposition was implicit in a route to the Null 0 interface. The modification elements are long-standing but newly applicable to all dispositions in Cisco IOS Release 11.2 F.
Selection options specify match criteria. When a call matches all selection criteria in an X.25 route, then the specified modification and disposition are used for the call.
As many as four selection options can be used to determine the route:
Table 47 lists the selection options for the x25 route command. At least one selection or modification element must be specified in the x25 route command.
| Selection Options | Description |
|---|---|
| destination-pattern | (Optional) Destination address pattern, which is a regular expression that can represent either one X.121 address (such as ^1111000$) or any address in a group of X.121 addresses (such as ^1111.*). |
| source source-pattern | (Optional) Source address pattern, which is a regular expression that can represent either one X.121 source address (such as ^2222000$) or any address in a group of X.121 addresses (such as ^2222.*). |
| dest-ext nsap-destination-pattern | (Optional) NSAP destination address pattern, which is a regular expression that can represent either an NSAP destination address (such as ^11.1111.0000$) or an NSAP prefix (such as ^11.1111.*).
Note: A period (.) in the pattern is interpreted as a character wildcard, which will not interfere with a match to the actual period in the NSAP; if desired, an explicit character match may be used (such as ^11\.1111\..*). |
| cud user-data-pattern | (Optional) Call user data (CUD) pattern, which is specified as a regular expression of printable ASCII text. The CUD field may be present in a call packet. The first few bytes (commonly 4 bytes long) identify a protocol; the specified pattern is applied to any user data after the protocol identification. |
Regular expressions are used to allow pattern-matching operations on the addresses and user data. A common operation is to do prefix matching on the X.121 DNIC field and route accordingly. The caret (^) is a special regular expression character that anchors the match at the beginning of the pattern. For example, the pattern ^3306 will match all X.121 addresses with a DNIC of 3306.
Addresses typically need to be modified when traffic from a private network that uses arbitrary X.121 addresses must transit a public data network, which must use its own X.121 addresses. The easiest way to meet the requirement is to specify in the x25 route command a way to modify the private address into a network X.121 address or to modify a network X.121 address into a private address. The addresses are modified so that no change to the private addressing scheme is required.
The modification options use the standard UNIX regular expression substitution operations to change an X.25 field. A pattern match is applied to an address field, which is rewritten as directed by a rewrite pattern.
Table 48 lists the modification options for the x25 route command. At least one selection or modification element must be specified in the x25 route command.
| Modification Option | Description |
|---|---|
| substitute-source rewrite-source | (Optional) Calling X.121 address rewrite pattern.
The source address, source-pattern, and this rewrite-source pattern are used to form a new source address. If no source-pattern is specified, any destination-pattern match pattern is used. If neither match pattern is specified, a default match pattern of .* is used. See Table 49 and Table 50 for summaries of pattern and character matching, respectively. See Table 51 for a summary of pattern rewrite elements. |
| substitute-dest rewrite-dest | (Optional) Called X.121 address rewrite pattern.
The destination address, destination-pattern, and this rewrite-dest pattern are used to form a new destination address. If no destination-pattern is specified, a default match pattern of .* is used. See Table 49 and Table 50 for summaries of pattern and character matching, respectively. See Table 51 for a summary of pattern rewrite elements. |
Source address. A modification of the source address is directed by the rewrite string using one of three possible match patterns. If the source source-pattern selection option is defined, it is used with the source-rewrite string to construct the new source address; otherwise, a destination-pattern regular expression is used (for backwards compatibility) or a wildcard regular expression (.*) is used. In the rewrite-source argument, the backslash character (\) indicates that the digit immediately following the argument selects a portion of the matched address to be inserted into the new called address.
Destination address. A modification of the destination address is directed by the rewrite string using one of two possible match patterns. If the destination-pattern selection option is defined, it is used with the destination-rewrite string to construct the new destination address; otherwise, a wildcard regular expression (.*) is used. In the rewrite-dest argument, the backslash character (\) indicates that the digit immediately following the argument selects a portion of the original called address to be inserted into the new called address.
Refer to Table 49, Table 50, and Table 51 for summaries of pattern matching, character matching, and pattern rewrite elements. Note that up to nine pairs of parentheses can be used to identify patterns to be included in the modified string. A more complete description of the pattern-matching characters is found in the "Regular Expressions" appendix in the Dial Solutions Command Reference.
| Pattern | Description |
|---|---|
| * | Matches 0 or more occurrences of the preceding character. |
| + | Matches 1 or more occurrences of the preceding character. |
| ? | Matches 0 or 1 occurrences of the preceding character.1 |
| Character | Description |
|---|---|
| ^ | Matches the beginning of the input string. |
| $ | Matches the end of the input string. |
| \char | Matches the single character char specified. |
| . | Matches any single character. |
| Pattern | Description |
|---|---|
| \0 | The pattern is replaced by the entire original address. |
| \1...9 | The pattern is replaced by strings that match the first through ninth parenthetical part of the X.121 address. |
The xot-source disposition option can improve the resilience of the TCP connection if, for instance, a loopback interface is specified. By default, a TCP connection's source IP address is that of the interface used to initiate the connection; a TCP connection will fail if either the source or destination IP address is no longer valid. Because a loopback interface never goes down, its IP address is always valid. Any TCP connections originated using a loopback interface can be maintained as long as a path exists to the destination IP address, which may also be the IP address of a loopback interface.
Table 52 lists the disposition choices for the x25 route command. You are required to select one of these choices.
| Disposition | Description |
|---|---|
| interface serial-interface | Route the selected call to the specified X.25 serial interface. |
| interface cmns-interface mac mac-address | Route the selected call out the specified broadcast interface via CMNS to the LAN destination station. The broadcast interface type can be Ethernet, Token Ring, or FDDI. The interface numbering scheme depends on the router interface hardware. |
| xot ip-address [ip2-address [...[ip6-address]]] [xot-source interface] | Route the selected call to the XOT host at the specified IP address. Subsequent IP addresses are tried, in sequence, only if XOT is unable to establish a TCP connection with a prior address. |
| clear | Terminate the call. |
TCP maintains each connection using a keepalive mechanism that starts with a default time period and number of retry attempts. If a received XOT connection is dispatched using a route with explicit keepalive parameters, those values will be used for the TCP connection. If an XOT connection is sent using a route with explicit keepalive parameters, those values will be used for the TCP connection.
Table 53 lists and describes the xot-keepalive options for the x25 route command.
| XOT-Keepalive Option | Description |
|---|---|
| xot-keepalive-period seconds | Number of seconds between keepalives for XOT connections. The default is 60 seconds. |
| xot-keepalive-tries count | Number of times TCP keepalives should be sent before dropping the connection. The default value is 4 times. |
If a matching route is found, the incoming call is forwarded to the next hop depending on the routing entry. If no match is found, the call is cleared. If the route specifies a serial interface running X.25 or a broadcast interface running CMNS, the router attempts to forward the call to that host. If the interface is not operational, the subsequent routes are checked for forwarding to an operational interface. If the interface is operational but out of available virtual circuits, the call is cleared. Otherwise, the expected Clear Request or Call Accepted message is forwarded back toward the originator. A call cannot be forwarded out the interface on which it arrived.
If the matching route specifies an XOT disposition, a TCP connection is established to port 1998 at the specified IP address, which must be an XOT host. The Call Request packet is forwarded to the remote host, which applies its own criteria to handle the call. If, upon receiving an XOT call, a routing table entry is not present, or the destination is unavailable, a Clear Request is sent back and the TCP connection is closed. Otherwise, the call is handled and the expected Clear Request or Call Accepted packet is returned. Incoming calls received via XOT connections that match a routing entry specifying an XOT destination are cleared. This restriction prevents Cisco routers from establishing an XOT connection to another router that would establish yet another XOT connection.
The following example uses regular expression pattern matching characters to match just the initial portion of the complete X.25 address. Any call with a destination address beginning with 3107 that is received on an interface other than serial 0 is forwarded to serial 0.
x25 route ^3107 interface serial 0
The following example prevents X.25 routing for calls that do not specify a source address:
x25 route source ^$ clear
The following example configures alternate XOT hosts for the routing entry. If the first address listed is not available, subsequent addresses are tried until a connection is made. If no connection can be formed, the call is cleared.
x25 route ^3106$ xot 172.20.2.5 172.20.7.10 172.10.7.9
The following example clears calls that contain a 3 in the source address. The disposition keyword clear is new:
x25 route source 3 clear
The following example clears calls that contain two consecutive 3's in the source address:
x25 route source 33 clear
The following example clears a call to the destination address, 9999:
x25 route ^9999$ clear
The following example specifies a route for specific source and destination addresses. (The ability to combine source and destination patterns is a new feature.)
x25 route ^9999$ source ^333$ interface serial 0
The following example routes the call to the XOT host at the specified IP address. The disposition keyword xot is new. In prior releases the keyword ip was used.
x25 route ^3333$ xot 172.21.53.61
The following example routes calls containing the destination extension address preamble 11.1234:
x25 route dest-ext ^11.1234.* interface serial 0
The following example rewrites the destination address as 9999. There must be a minimum of four 8's in the address. (8888888 will change to 9999.)
x25 route 8888 substitute-dest 9999 interface serial 0
The following example substitutes only part of the destination address. "^88" specifies the original destination string must begin with 88. "(.*)" indicates the string can end with any number, 0-9, and can be more than one digit. "99\1" changes the destination address to 99 plus whatever matches ".*" in the original destination address. For example, 8881 will change to 9981.
x25 route ^88(.*) substitute-dest 99\1 interface serial 0
The following example substitutes only part of the destination address and also removes a specified number of digits from the address. "^88" specifies the original destination string must begin with 88. "(..)" matches any two digits. "(.*)" specifies the string can end with any number, 0-9, and can occur zero or more times. Thus any address that starts with 88 and has four or more digits will be rewritten to start with 99 and omit the third and fourth digits. For example, 881234 will change to 9934.
x25 route ^88(..)(.*) substitute-dest 99\2 interface serial 0
The following example looks for a specified destination address and changes the source address. "9999" is the destination address. The original source address changes to "2222" because the call is made to the destination 9999.
x25 route ^9999$ substitute-source 2222 interface serial 0
The following example rewrites the source address based upon the source address. "9999" matches any destination address with four consecutive 9s. "^...(.*)" matches any source address with at least three digits; the command removes the first three digits and rewrites any digits after the first three as the new source address. For example, a call to 9999 from the source address 77721 will be forwarded using the calling address 21 and the called address 9999.
x25 route 9999 source ^...(.*) substitute-source \1 interface serial 0
The following example adds a digit to the source and destination addresses patterns. "09990" is the destination address pattern. The source can be any address. "9\0" specifies to add a leading 9 to the destination address pattern. "3\0" specifies to add a leading 3 to the source address pattern. For example, a call using source 03330 and destination 09990 will change to 303330 and 909990, respectively.
x25 route 09990 source .* substitute-dest 9\0 substitute-source 3\0 interface serial 0
You can use the master indexes or search online to find documentation of related commands.
To enable X.25 switching or tunneling, use the x25 routing global configuration command. To disable the forwarding of X.25 calls, used the no form of this command.
x25 routing [use-tcp-if-defs]| use-tcp-if-defs | (Optional) May be used to modify the acceptance of calls received over TCP. |
Disabled
Global configuration
This command first appeared prior to Cisco IOS Release 10.0.
The x25 routing command enables X.25 switching between the X.25 services (X.25, CMNS and XOT). X.25 calls will not be forwarded until this command is issued.
The use-tcp-if-defs keyword may be needed for receiving XOT calls from routers using older software versions. Normally, calls received over a TCP connection (remote routing reception) will have the flow control parameters (window sizes and maximum packet sizes) indicated, because proper operation of routed X.25 requires that these values match at both ends of the connection.
Some previous versions of our software, however, do not ensure that these values are present in all calls. In this case, the Cisco IOS software normally forces universally acceptable flow control values (window sizes of 2 and maximum packet sizes of 128) on the connection. Because some equipment disallows modification of the flow control values in the call confirm, the use-tcp-if-defs keyword causes the router to use the default flow control values of the outgoing interface and indicate the resulting values in the call confirm. This modified behavior may allow easier migration to newer versions of the Cisco IOS software.
The following example enables X.25 switching:
x25 routing
To specify a sequence of packet network carriers, use the x25 roa global configuration command. To remove the specified name, use the no form of this command.
x25 roa name number| name | Recognized Operating Agency (ROA, formerly called a Recognized Private Operating Agency, or RPOA), which must be unique with respect to all other ROA names. It is used in the x25 facility and x25 map interface configuration commands. |
| number | A sequence of 1 or more numbers used to describe an ROA; up to 10 numbers are accepted. |
No packet network carriers are specified.
Global configuration
This command first appeared prior to Cisco IOS Release 10.0.
This command specifies a list of transit ROAs to use, referenced by name.
The following example sets an ROA name and then sends the list via the X.25 user facilities:
x25 roa green_list 23 35 36
interface serial 0
x25 facility roa green_list
x25 map ip 172.20.170.26 10 roa green_list
You can use the master indexes or search online to find documentation of related commands.
This command has no arguments or keywords.
The called address is sent.
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
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.
As of Cisco IOS Release 11.3, this command also applies to PAD calls.
The following example suppresses or omits the called address in Call Request packets:
interface serial 0
x25 suppress-called-address
To omit the source address in outgoing calls, use the x25 suppress-calling-address interface configuration command. To reset this command to the default state, use the no form of this command.
x25 suppress-calling-addressThis command has no arguments or keywords.
The calling address is sent.
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
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.
As of Cisco IOS Release 11.3, this command also applies to PAD calls.
The following example suppresses or omits the calling address in Call Request packets:
interface serial 0
x25 suppress-calling-address
Use the x25 t10 interface configuration command to set the value of the Restart Indication retransmission timer (T10) on DCE devices.
x25 t10 seconds| seconds | Time in seconds. The default is 60 seconds. |
60 seconds
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
The following example sets the T10 timer to 30 seconds:
interface serial 0
x25 t10 30
To set the value of the Incoming Call timer (T11) on DCE devices, use the x25 t11 interface configuration command.
x25 t11 seconds| seconds | Time in seconds. The default is 180 seconds. |
180 seconds
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
The following example sets the T11 timer to 90 seconds:
interface serial 0
x25 t11 90
To set the value of the Reset Indication retransmission timer (T12) on DCE devices, use the x25 t12 interface configuration command.
x25 t12 seconds| seconds | Time in seconds. The default is 60 seconds. |
60 seconds
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
The following example sets the T12 timer to 30 seconds:
interface serial 0
x25 t12 30
To set the value of the Clear Indication retransmission timer (T13) on DCE devices, use the x25 t13 interface configuration command.
x25 t13 seconds| seconds | Time in seconds. The default is 60 seconds. |
60 seconds
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
The following example sets the T13 timer to 30 seconds:
interface serial 0
x25 t13 30
To set the value of the Restart Request retransmission timer (T20) on DTE devices, use the x25 t20 interface configuration command.
x25 t20 seconds| seconds | Time in seconds. The default is 180 seconds. |
180 seconds
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
The following example sets the T20 timer to 90 seconds:
interface serial 0
x25 t20 90
To set the value of the Call Request timer (T21) on DTE devices, use the x25 t21 interface configuration command.
x25 t21 seconds| seconds | Time in seconds. The default is 200 seconds. |
200 seconds
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
The following example sets the T21 timer to 100 seconds:
interface serial 0
x25 t21 100
To set the value of the Reset Request retransmission timer (T22) on DTE devices, use the x25 t22 interface configuration command.
x25 t22 seconds| seconds | Time in seconds. The default is 180 seconds. |
180 seconds
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
The following example sets the T22 timer to 90 seconds:
interface serial 0
x25 t22 90
To set the value of the Clear Request retransmission timer (T23) on DTE devices, use the x25 t23 interface configuration command.
x25 t23 seconds| seconds | Time in seconds. The default is 180 seconds. |
180 seconds
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
The following example sets the T23 timer to 90 seconds:
interface serial 0
x25 t23 90
To set the data packet acknowledgment threshold, use the x25 threshold interface configuration command.
x25 threshold delay-count| delay-count | Value between zero and the input window size. A value of 1 sends one Receiver Ready acknowledgment per packet. The default is 0, which disables the acknowledgment threshold. |
0 (which disables the acknowledgment threshold)
Interface configuration
This command first appeared in Cisco IOS Release 11.2F; it replaces the longstanding form x25 th.
This command instructs the router to send acknowledgment packets when it is not busy sending other packets, even if the number of input packets has not reached the input window size count.
The router sends an acknowledgment packet 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 router will send an acknowledgment per input packet if unable to "piggyback" the acknowledgment of an outgoing data packet. This command improves line responsiveness at the expense of bandwidth.
This command only applies to encapsulated traffic over X.25 (datagram transport), not to routed traffic.
The following example sends an explicit Receiver Ready acknowledgment when it has received 5 data packets that it has not acknowledged:
interface serial 1
x25 threshold 5
You can use the master indexes or search online to find documentation of related commands.
To override the X.121 addresses of outgoing calls forwarded over a specific interface, use the x25 use-source-address interface configuration command. Use the no form of this command to prevent updating the source addresses of outgoing calls.
x25 use-source-addressThis command has no arguments or keywords.
Disabled
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
Some X.25 calls, when forwarded by the X.25 switching support, need the calling (source) X.121 address updated to that of the outgoing interface. This update is necessary when you are forwarding calls from private data networks to public data networks (PDNs).
The following example shows how to prevent updating the source addresses of outgoing X.25 calls on serial interface 0 once calls have been forwarded:
interface serial 0
no x25 use-source-address
To change the default incoming window size to match that of the network, use the x25 win interface configuration command.
x25 win packets| packets | Packet count that can range from 1 to one less than the window modulus. |
2 packets
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
This command determines the default number of packets a virtual circuit 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 5 packets may be received before an X.25 acknowledgment is sent:
interface serial 1
x25 win 5
You can use the master indexes or search online to find documentation of related commands.
x25 modulo
x25 threshold
x25 wout
To change the default outgoing window size to match that of the network, use the x25 wout interface configuration command.
x25 wout packets| packets | Packet count that can range from 1 to one less than the window modulus. |
2 packets
Interface configuration
This command first appeared prior to Cisco IOS Release 10.0.
This command determines the default number of packets a virtual circuit 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 a default limit of 5 for the number of outstanding unacknowledged packets for virtual circuits:
interface serial 1
x25 wout 5
You can use the master indexes or search online to find documentation of related commands.
x25 modulo
x25 threshold
x25 win
To limit access to the access 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} x121-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. |
| x121-address | If applied as an inbound access class, specifies the X.121 address that can or cannot have access (with or without regular expression pattern-matching characters). The X.121 address is the source address of the incoming packet.
If applied as an outbound access class, then the address specifies a destination to where connections are allowed. |
No access lists are defined.
Global configuration
This command first appeared in Cisco IOS Release 10.0.
An access list can contain any number of access list items. The list items 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 expressions in the access list, access is denied.
Access lists take advantage of the message field defined by Recommendation X.29, which describes procedures for exchanging data between two PADs, or between 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 allow many addresses to be matched by a single regular expressions. For more information, refer to the "Regular Expressions" appendix in the Dial Solutions Command Reference.
The access lists must be applied to a vty with the access-class command.
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 {default | name} parameter:value [parameter:value]| default | Specifies default profile script. |
| name | Name of the PAD profile script. |
| parameter:value | X.3 PAD parameter number and value separated by a colon. You can specify multiple parameter-value pairs. |
The default PAD profile script is used. The default for inbound connections is:
2:0, 4:1, 15:0, 7:21
Global configuration
This command first appeared in Cisco IOS Release 10.0.
When an X.25 connection is established, the access 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 access server accordingly.
For incoming PAD connections, the Protocol Translator uses a default PAD profile to set the remote X.3 PAD parameters unless a profile script is defined with the translate command.
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 packet. The name linemode is used with the translate command to effect use of this script.
x29 profile linemode 2:1 3:2 15:1
To override the default PAD profile, create a PAD profile script named "default" by using the following command:
x29 profile default 2:1 4:1, 15:0, 4:0
You can use the master indexes or search online to find documentation of related commands.
translate
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