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Cisco IOS Release 12.0 Wide-Area Networking Command Reference
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About the Cisco IOS Software Documentation
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ATM Commands (abr through atm sonet stm-1)
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ATM Commands (atm txbuff through network-clock-select)
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ATM Commands (oam-pvc through show atm traffic)
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ATM Commands (show atm vc through vc-class atm)
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Frame Relay Commands
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SMDS Commands
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X.25 and LAPB Commands
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X.25 Facility Handling
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Table Of Contents
X.25 and LAPB Commands
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:
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Between interfaces—for local routing
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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.
access-class
To configure an incoming access class on virtual terminals, use the access-class line configuration command.
access-class access-list-number in
Syntax Description
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.
Defaults
No incoming access class is defined.
Command Modes
Line configuration
Command History
Usage Guidelines
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.
Examples
The following example configures an incoming access class on virtual terminal line 4. For information on the line vty command see the Configuring the Route Processor for the Catalyst 8540 and Using Flash Memory Cards publication.
line vty 4access-class 4 inRelated Commands
access-list
Configures the access list mechanism for filtering frames by protocol type or vendor code.
Limits access to the access server from certain X.25 hosts.
bfe
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
Syntax Description
Defaults
None.
Command Modes
EXEC
Command History
Examples
The following example enables an interface to participate in BFE emergency mode:
bfe enter serial 0Related Commands
clear x25
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]
Syntax Description
Command Modes
Privileged EXEC
Command History
11.2
This command was introduced. It replaces the clear x25-vc command, which first appeared in Cisco IOS Release 8.3.
Usage Guidelines
This command 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.
Examples
The following command clears the SVC or resets the PVC specified:
clear x25 serial 0 1The following command forces an X.25 restart, which implicitly clears all SVCs and resets all PVCs using the interface:
clear x25 serial 0The following command restarts the specified CMNS service (if active), which implicitly clears all SVCs using the service:
clear x25 ethernet 0 0001.0002.0003Related Commands
Clears an XOT SVC or resets an XOT PVC.
Displays information pertaining to the X.25 services.
clear x25-vc
This command is replaced by the clear x25 command.
clear xot
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
Syntax Description
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.
Command Modes
EXEC
Command History
Usage Guidelines
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.
Examples
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 2000Related Commands
cmns enable
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 enable
no cmns enable
Syntax Description
This command has no arguments or keywords.
Defaults
Each nonserial interface must be explicitly configured to use CMNS.
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Examples
The following example enables CMNS on Ethernet interface 0:
interface ethernet 0cmns enableRelated Commands
Creates an entry in the X.25 routing table (to be consulted for forwarding incoming calls and for placing outgoing PAD or protocol translation calls).
encapsulation lapb
To exchange datagrams over a serial interface using LAPB encapsulation, use the encapsulation lapb interface configuration command.
encapsulation lapb [dte | dce] [multi | protocol]
Syntax Description
Defaults
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.
Command Modes
Interface configuration
Command History
10.0
This command was introduced.
10.3
The following arguments and keywords were introduced:
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•
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Usage Guidelines
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.
Examples
The following example sets the operating mode as DTE and specifies that AppleTalk protocol traffic will be carried on the LAPB line:
interface serial 1encapsulation lapb dte appletalkRelated Commands
encapsulation x25
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]
Syntax Description
Defaults
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.
Command Modes
Interface configuration
Command History
10.0
This command was introduced.
10.3
The following keywords were added:
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•
•
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•
Usage Guidelines
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.
Examples
The following example configures the interface for connection to a BFE device:
interface serial 0encapsulation x25 bfeRelated Commands
lapb interface-outage
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
Syntax Description
milliseconds
Number of milliseconds a hardware outage can last without the protocol disconnecting the service.
Defaults
0 ms, which disables this feature.
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Examples
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 iplapb interface-outage 100lapb k
To specify the maximum permissible number of outstanding frames, called the window size, use the lapb k interface configuration command.
lapb k window-size
Syntax Description
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).
Defaults
7 frames
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Examples
The following example sets the LAPB window size (the k parameter) to 10 frames:
interface serial 0lapb modulolapb k 10Related Commands
lapb modulo
To specify the LAPB basic (modulo 8) or extended (modulo 128) protocol mode, use the lapb modulo interface configuration command.
lapb modulo modulus
Syntax Description
modulus
Either 8 or 128. The value 8 specifies LAPB's basic mode; the value 128 specifies LAPB's extended mode.
Defaults
Modulo 8
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Examples
The following example configures a high-speed X.25 link to use LAPB's extended mode:
interface serial 1encapsulation x25lapb modulo 128lapb k 40clock rate 2000000Related Commands
Specifies the maximum permissible number of outstanding frames, called the window size.
lapb n1
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
Syntax Description
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.
Defaults
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.
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Caution
Examples
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 1router(config)# lapb n1 ?<1080-12056> LAPB N1 parameter (bits; multiple of 8)The following example sets the N1 bits to 16440:
interface serial 0lapb n1 16440mtu 2048Related Commands
lapb n2
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
Syntax Description
Defaults
20 transmissions
Command Modes
Interface configuration
Command History
Examples
The following example sets the N2 tries to 50:
interface serial 0lapb n2 50lapb protocol
This command is obsolete. It has been replaced by the [protocol | multi] option of the encapsulation lapb command.
lapb t1
To set the retransmission timer period (the LAPB T1 parameter), use the lapb t1 interface configuration command.
lapb t1 milliseconds
Syntax Description
Defaults
3000 ms
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Examples
The following example sets the T1 retransmission timer to 2000 ms:
interface serial 0lapb t1 2000lapb t2
To set the explicit acknowledge deferral timer (the Link Access Procedure, Balanced [LAPB] T2 parameter), use the lapb t2 interface configuration command.
lapb t2 milliseconds
Syntax Description
milliseconds
Time in milliseconds. It can be a value from 1 to 32000. Default is 0 ms (disabled) and the recommended setting.
Defaults
0 ms (disabled), which means that the software will send an acknowledgement as quickly as possible.
Command Modes
Interface configuration
Command History
Usage Guidelines
The explicit acknowledge deferral timer determines the time that the software waits before sending an explicit acknowledgement. The acknowledgement is piggybacked with the data, unless there is no data and then an explicit acknowledgement is sent when the timer expires.
Caution
Related Commands
lapb t4
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
Syntax Description
Defaults
0 seconds
Command Modes
Interface configuration
Command History
Usage Guidelines
Any non-zero T4 duration must be greater than T1, the LAPB retransmission timer period.
Examples
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 serial0encapsulation x25lapb t4 10Related Commands
Specifies the maximum number of times a data frame can be sent (the LAPB N2 parameter).
Sets the retransmission timer period (the LAPB T1 parameter).
service pad
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]
no service pad [cmns]
Syntax Description
cmns
(Optional) Specifies sending and receiving PAD calls over CMNS.
from-xot
(Optional) Accept XOT to PAD connections.
to-xot
(Optional) Allow outgoing PAD calls over XOT.
Defaults
All PAD commands and associated connections are enabled. PAD services over XOT or CMNS are not enabled.
Command Modes
Global configuration
Command History
Usage Guidelines
The options from-xot and to-xot enable PAD calls to destinations that are not reachable over physical X.25 interfaces, but instead over TCP tunnels. This feature is known as PAD over XOT (X.25 over TCP).
Examples
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 padRouter(config)# x29 ?% Unrecognized commandRouter(config)# exitRouter# pad ?% Unrecognized commandIf 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 terminalEnter configuration commands, one per line. End with CNTL/Z.Router(config)# service padRouter(config)# x29 ?access-list Define an X.29 access listinviteclear-time Wait for response to X.29 Invite Clear messageprofile Create an X.3 profileRouter# pad ?WORD X121 address or name of a remote systemIn the following example, PAD services over CMNS are enabled:
! Enable CMNS on a nonserial interfaceinterface ethernet0cmns enable!!Enable inbound and outbound PAD over CMNS serviceservice pad cmns!! Specify an X.25 route entry pointing to an interface's CMNS destination MAC addressx25 route ^2193330 interface Ethernet0 mac 00e0.b0e3.0d62Router# show x25 vcSVC 1, State: D1, Interface: Ethernet0Started 00:00:08, last input 00:00:08, output 00:00:08Line: 0 con 0 Location: console Host: 2193330connected to 2193330 PAD <--> CMNS Ethernet0 00e0.b0e3.0d62Window size input: 2, output: 2Packet size input: 128, output: 128PS: 2 PR: 3 ACK: 3 Remote PR: 2 RCNT: 0 RNR: noP/D state timeouts: 0 timer (secs): 0data bytes 54/19 packets 2/3 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0Related Commands
service pad from-xot
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-xot
no service pad from-xot
Syntax Description
This command has no arguments or keywords.
Defaults
Incoming XOT connections are ignored.
Command Modes
Global configuration
Command History
Usage Guidelines
If service pad from-xot is enabled, the Calls received using the XOT service may be accepted for processing a PAD session.
Examples
The following example prevents incoming XOT Calls from being accepted as a PAD session:
no service pad from-xotRelated Commands
service pad to-xot
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-xot
no service pad to-xot
Syntax Description
This command has no arguments or keywords.
Defaults
XOT routes pointing to XOT are not considered.
Command Modes
Global configuration
Command History
Examples
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-xotRelated Commands
show cmns
Effective with Cisco IOS Release 11.3, this command is no longer available.
show x25 interface
To display information about VCs that use an X.25 interface and, optionally, about a specified virtual circuit, use the show x25 interface EXEC command.
show x25 interface [serial number | cmns-interface mac mac-address]
Syntax Description
Command Modes
EXEC
Command History
Examples
The following show x25 interface sample output displays X.25 information about VCs on serial interface 0:
Router# show x25 interface serial 0SVC 1, State: D1, Interface: Serial0Started 00:13:52, last input 00:00:05, output neverConnects 3334 <-> ip 3.3.3.4Call PID ietf, Data PID noneWindow size input: 7, output: 7Packet size input: 512, output: 512PS: 0 PR: 6 ACK: 1 Remote PR: 0 RCNT: 5 RNR: noP/D state timeouts: 0 timer (secs): 0data bytes 0/2508 packets 0/54 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0SVC 32, State: D1, Interface: Serial0.11Started 00:16:53, last input 00:00:37, output 00:00:28Connects 3334 <-> clnsCall PID cisco, Data PID noneWindow size input: 7, output: 7Packet size input: 512, output: 512PS: 5 PR: 4 ACK: 4 Remote PR: 4 RCNT: 0 RNR: noP/D state timeouts: 0 timer (secs): 0data bytes 378/360 packets 21/20 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0show x25 map
To display information about configured address maps, use the show x25 map EXEC command.
show x25 map
Syntax Description
This command has no arguments or keywords.
Command Modes
EXEC
Command History
Usage Guidelines
The show x25 map command shows information about the following:
•
•
•
•
Examples
The following is sample output from the show x25 map command:
Router# show x25 mapSerial0: X.121 1311001 <--> ip 172.20.170.1PERMANENT, BROADCAST, 2 VCS: 3 4*Serial0: X.121 1311005 <--> appletalk 128.1PERMANENTSerial1: X.121 2194441 cud hello <--> padPERMANENT, windowsize 5 5, accept-reverse, idle 5Serial1: X.121 1311005 <--> bridgePERMANENT, BROADCASTSerial2: 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,clnsPERMANENT, NVC 8, 1 VC: 1024The display shows that four maps have been configured for a router: two for serial interface 0, one for serial interface 1, and one for the serial interface 2 (which maps eight protocols to the host).
Table 62 describes fields shown in the display.
show x25 remote-red
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-red
Syntax Description
This command has no arguments or keywords.
Command Modes
EXEC
Command History
Examples
The following is sample output from the show x25 remote-red command:
Router# show x25 remote-redEntry REMOTE-RED REMOTE-BLACK INTERFACE1 21.0.0.3 21.0.0.7 serial32 21.0.0.10 21.0.0.6 serial13 21.0.0.24 21.0.0.8 serial3Table 63 describes significant fields shown in the display.
show x25 route
To display the X.25 routing table, use the show x25 route EXEC command.
show x25 route
Syntax Description
This command has no arguments or keywords.
Command Modes
EXEC
Command History
Examples
The following is sample output from the show x25 route command:
Router# show x25 route# Match Substitute Route To1 ^1311001$ Serial0, 0 uses2 ^1311002$ xot 172.20.170.10Table 64 describes significant fields shown in the display.
Related Commands
Creates an entry in the X.25 routing table (to be consulted for forwarding incoming calls and for placing outgoing PAD or protocol translation calls).
show x25 services
To display information pertaining to the X.25 services, use the show x25 services EXEC command.
show x25 services
Syntax Description
This command has no arguments or keywords.
Command Modes
EXEC
Command History
Usage Guidelines
This command is the default form of the show x25 command.
Examples
The following is sample output from the show x25 services command:
Router# show x25 servicesX.25 software, Version 3.0.0.3 configurations supporting 3 active contextsVCs allocated, freed and in use: 7 - 0 = 7VCs active and idle: 4, 3XOT software, Version 2.0.0.VCs allocated, freed and in use: 2 - 1 = 1connections in-progress: 0 outgoing and 0 incomingactive VCs: 1, connected to 1 remote hostsRelated Commands
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]
Syntax Description
Command Modes
EXEC
Command History
Usage Guidelines
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.
Examples
Encapsulated Traffic Example
The following is sample output from the show x25 vc command used on an encapsulated traffic circuit:
Router# show x25 vc 1024SVC 1024, State: D1, Interface: Serial0Started 0:00:31, last input 0:00:31, output 0:00:31Connects 170090 <-->compressedtcp 172.20.170.90ip 172.20.170.90Call PID multi, Data PID ietfReverse chargedWindow size input: 2, output: 2Packet size input: 128, output: 128PS: 5 PR: 5 ACK: 4 Remote PR: 5 RCNT: 1 RNR: FALSEWindow is closedP/D state timeouts: 0 Timer (secs): 0data bytes 505/505 packets 5/5 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0Table 65 describes the fields shown in the sample output that are typical for virtual circuits.
Table 65 show x25 vc Field Descriptions
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 66, Table 67, Table 68 and Table 69 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.
1 The ITU-T carries out the functions of the former Consultative Committee for International Telegraph and Telephone (CCITT).
Table 66 describes the connection fields specific for encapsulation traffic.
Locally Switched X.25 Traffic Example
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 vcPVC 1, State: D1, Interface: Serial2Started 0:01:26, last input never, output neverPVC <--> Serial1 PVC 1, connectedWindow size input: 2, output: 2Packet size input: 128, output: 128PS: 0 PR: 0 ACK: 0 Remote PR: 0 RCNT: 0 RNR: FALSEP/D state timeouts: 0 Timer (secs): 0data bytes 0/0 packets 0/0 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0SVC 5, State: D1, Interface: Serial2Started 0:00:16, last input 0:00:15, output 0:00:15Connects 170093 <--> 170090 from Serial1 VC 5Window size input: 2, output: 2Packet size input: 128, output: 128PS: 5 PR: 5 ACK: 4 Remote PR: 5 RCNT: 1 RNR: FALSEP/D state timeouts: 0 Timer (secs): 0data bytes 505/505 packets 5/5 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0Table 67 describes the connection fields for virtual circuits carrying locally switched X.25 traffic.
Table 67 show x25 vc Local Traffic Field Descriptions
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 70 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.
Locally Switched X.25 Traffic between PVCs and SVCs Example
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 vcPVC 5, State: D1, Interface: Serial0Started 4d21h, last input 00:00:14, output 00:00:14Connects 101600 <--> 201700 from Serial2 VC 700D-bit permittedWindow size input: 2, output: 2Packet size input: 128, output: 128PS: 5 PR: 5 ACK: 4 Remote PR: 5 RCNT: 1 RNR: noP/D state timeouts: 0 timer (secs): 0data bytes 1000/1000 packets 10/10 Resets 1/0 RNRs 0/0 REJs 0/0 INTs 0/0SVC 700, State: D1, Interface: Serial2Started 00:00:16, last input 00:00:16, output 00:00:16Connects 101600 <--> 201700 from Serial0 PVC 5Window size input: 2, output: 2Packet size input: 128, output: 128PS: 5 PR: 5 ACK: 5 Remote PR: 4 RCNT: 0 RNR: noP/D state timeouts: 0 timer (secs): 103data bytes 500/500 packets 5/5 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0Table 68 describes the connection fields for virtual circuits carrying locally switched X.25 traffic between PVCs and SVCs.
Remotely Switched X.25 Traffic Example
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 vcPVC 2, State: D1, Interface: Serial2Started 0:01:25, last input never, output neverPVC <--> [172.20.165.92] Serial2/0 PVC 1 connectedXOT between 171.20.165.91, 1998 and 172.20.165.92, 27801Window size input: 2, output: 2Packet size input: 128, output: 128PS: 0 PR: 0 ACK: 0 Remote PR: 0 RCNT: 0 RNR: FALSEP/D state timeouts: 0 Timer (secs): 0 Reassembly (bytes): 0Held Fragments/Packets: 0/0data bytes 0/0 packets 0/0 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0SVC 6, State: D1, Interface: Serial2Started 0:00:04, last input 0:00:04, output 0:00:04Connects 170093 <--> 170090 fromXOT between 172.20.165.91, 1998 and 172.20.165.92, 27896Window size input: 2, output: 2Packet size input: 128, output: 128PS: 5 PR: 5 ACK: 4 Remote PR: 5 RCNT: 1 RNR: FALSEP/D state timeouts: 0 Timer (secs): 0 Reassembly (bytes): 0Held Fragments/Packets: 0/0data bytes 505/505 packets 5/5 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0Table 69 describes the connection fields for virtual circuits carrying remotely switched X.25 traffic.
Table 69 show x25 vc Remote X.25 Traffic Field Descriptions
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 70 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 70 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.
show x25 xot
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]]
Syntax Description
local ip-address [port port]
(Optional) Local IP address and optional port number.
remote ip-address [port port]
(Optional) Remote IP address and optional port number.
Command Modes
EXEC
Command History
Examples
The following show x25 xot sample output displays information about all XOT virtual circuits:
Router> show x25 xotSVC 11, State: D1, Interface: [2.2.2.2,1998/2.2.2.1,11002]Started 00:00:08, last input 00:00:08, output 00:00:08Line: 0 con 0 Location: Host: 5678111 connected to 5678 PAD <--> XOT 2.2.2.2,1998Window size input: 2, output: 2Packet size input: 128, output: 128PS: 2 PR: 3 ACK: 3 Remote PR: 2 RCNT: 0 RNR: noP/D state timeouts: 0 timer (secs): 0data bytes 54/18 packets 2/3 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0Related Commands
Displays information about VCs that use an X.25 interface and, optionally, about a specified VC.
Displays information pertaining to the X.25 services.
x25 accept-reverse
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-reverse
no x25 accept-reverse
Syntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Examples
The following example sets acceptance of reverse charge calls:
interface serial 0x25 accept-reverseRelated Commands
x25 address
To set the X.121 address of a particular network interface, use the x25 address interface configuration command.
x25 address x121-address
Syntax Description
Defaults
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.
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Examples
The following example sets the X.121 address for the interface:
interface serial 0encapsulation x25x25 address 00000123005The address must match that assigned by the X.25 network service provider.
x25 alias
To configure an interface alias address that will allow this interface to accept calls with other destination addresses, use the x25 alias interface configuration command.
x25 alias {destination-pattern | x121-address-pattern} [cud cud-pattern]
Syntax Description
Defaults
No alias is configured.
Command Modes
Interface configuration
Command History
11.2
This command was introduced. It replaces the functionality that was provided by the alias keyword of the x25 route command.
Usage Guidelines
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.
Examples
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 0encapsulation x25x25 address 0000123x25 alias ^1111123.*x25 bfe-decision
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}
Syntax Description
Defaults
The router does not participate in emergency mode.
Command Modes
Interface configuration
Command History
Examples
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 bfe enter EXEC command to direct the router to participate in emergency mode.
interface serial 0x25 bfe-emergency decisionx25 remote-red 21.0.0.12 remote-black 21.0.0.1x25 bfe-decision askRelated Commands
x25 bfe-emergency
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}
Syntax Description
Defaults
No address translation information is sent to the BFE.
Command Modes
Interface configuration
Command History
Examples
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 bfe enter EXEC command to direct the router to participate in emergency mode.
interface serial 0x25 bfe-emergency decisionx25 remote-red 21.0.0.12 remote-black 21.0.0.1x25 bfe-decision askRelated Commands
x25 default
To set a default protocol, use the x25 default interface configuration command. To remove the default protocol specified, use the no form of this command.
x25 default protocol
no x25 default protocol
Syntax Description
Defaults
None.
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Examples
The following example establishes IP as the default protocol for X.25 calls:
interface serial 0x25 default ipRelated Commands
x25 facility
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 option value
no x25 facility option value
Syntax Description
option
Set of user facilities options. See Table 71 for a list of supported facilities and their values.
value
Option value. See Table 71 for a list of supported facilities and their values.
Defaults
No facility is sent.
Command Modes
Interface configuration
Command History
Usage Guidelines
Table 71 lists the set of x25 facility command user facilities options.
Examples
The following example specifies a transit delay value in an X.25 configuration:
interface serial 0x25 facility transit-delay 24000The following example sets an ROA name and then sends the list via the X.25 user facilities:
x25 roa green_list 23 35 36interface serial 0x25 facility roa green_listRelated Commands
x25 hic
To set the highest incoming-only virtual circuit (VC) number, use the x25 hic interface configuration command.
x25 hic circuit-number
Syntax Description
Defaults
0
Command Modes
Interface configuration
Command History
Usage Guidelines
This command is applicable only if you have the X.25 switch configured for an incoming-only VC 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.
Examples
The following example sets a valid incoming-only VC range of 1 to 5:
interface serial 0x25 lic 1x25 hic 5Related Commands
x25 hoc
To set the highest outgoing-only virtual circuit (VC) number, use the x25 hoc interface configuration command.
x25 hoc circuit-number
Syntax Description
Defaults
0
Command Modes
Interface configuration
Command History
Usage Guidelines
This command is applicable only if you have the X.25 switch configured for an outgoing-only VC 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.
Examples
The following example sets a valid outgoing-only VC range of 2000 to 2005:
interface serial 0x25 loc 2000x25 hoc 2005Related Commands
x25 hold-queue
To set the maximum number of packets to hold until a virtual circuit (VC) 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
no x25 hold-queue [packets]
Syntax Description
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.
Defaults
10 packets
Command Modes
Interface configuration
Command History
Usage Guidelines
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 VC hold queue value is determined when it is created; changing this parameter will not affect the hold queue limits of the existing virtual circuits.
Examples
The following example sets the X.25 hold queue to hold 25 packets:
interface serial 0x25 hold-queue 25Related Commands
x25 hold-vc-timer
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
no x25 hold-vc-timer
Syntax Description
minutes
Number of minutes to prevent calls trying a previously failed destination. Incoming calls are still accepted.
Defaults
0 minutes
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Examples
The following example sets this timer to 3 minutes:
interface serial 0x25 hold-vc-timer 3x25 host
To define a static host name-to-address mapping, use the x25 host global configuration command. Use the no form of the command to remove the host name.
x25 host name x121-address [cud call-user-data]
no x25 host name
Syntax Description
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.
Defaults
No static host name-to-address mapping is defined.
Command Modes
Global configuration
Command History
Usage Guidelines
This command permits you to map an X.121 address to an easily recognizable name. You can later use this host name instead of the X.121 address when you issue the translate command for X.25.
Examples
The following example specifies a static address mapping:
x25 host Willard 4085551212The following example removes a static address mapping:
no x25 host WillardThe following example specifies static address mapping from the X.121 address 12345678 to the host name masala. It then uses the name masala in the translate command in place of the X.121 address when translating from the X.25 host to the PPP host with address 10.0.0.2.
x25 host masala 12345678translate x25 masala ppp 10.0.0.2 routingRelated Commands
x25 htc
To set the highest two-way virtual circuit (VC) number, use the x25 htc interface configuration command.
x25 htc circuit-number
Syntax Description
Defaults
1024 for X.25 network service interfaces; 4095 for CMNS network service interfaces.
Command Modes
Interface configuration
Command History
Usage Guidelines
This command is applicable if the X.25 switch is configured for a two-way VC range. Any two-way VC range must come after (that is, be numerically larger than) any incoming-only range, and must come before any outgoing-only range.
Examples
The following example sets a valid two-way VC range of 5 to 25:
interface serial 0x25 ltc 5x25 htc 25Related Commands
x25 idle
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
Syntax Description
Defaults
0 (the SVC is kept open indefinitely)
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Examples
The following example sets a 5-minute wait period before an idle circuit is cleared:
interface serial 2x25 idle 5Related Commands
x25 ip-precedence
To enable the Cisco IOS software to use the IP precedence value when it opens a new virtual circuit, use the x25 ip-precedence interface configuration command. To cause the Cisco IOS software to ignore the precedence value when opening virtual circuits (VCs), use the no form of this command.
x25 ip-precedence
no x25 ip-precedence
Syntax Description
This command has no arguments or keywords.
Defaults
The router opens one VC for all types of service.
Command Modes
Interface configuration
Command History
Usage Guidelines
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 VC 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 VCs 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.
Examples
The following example allows new IP encapsulation VCs based on the IP precedence:
interface serial 3x25 ip-precedencex25 ips
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
Syntax Description
bytes
Byte count. It can be one of the following values: 16, 32, 64, 128, 256, 512, 1024, 2048, or 4096.
Defaults
128 bytes
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Note
Examples
The following example sets the default maximum packet sizes to 512:
interface serial 1x25 ips 512x25 ops 512Related Commands
x25 lic
To set the lowest incoming-only virtual circuit (VC) number, use the x25 lic interface configuration command.
x25 lic circuit-number
Syntax Description
Defaults
0
Command Modes
Interface configuration
Command History
Usage Guidelines
This command is applicable only if you have the X.25 switch configured for an incoming-only VC 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 VC range.
Examples
The following example sets a valid incoming-only VC range of 1 to 5, and sets the lowest two-way VC number:
interface serial 0x25 lic 1x25 hic 5x25 ltc 6Related Commands
x25 linkrestart
To force X.25 Level 3 (packet level) to restart when Level 2 (LAPB, the link level) resets, use the x25 linkrestart interface configuration command. To disable this function, use the no form of this command.
x25 linkrestart
no x25 linkrestart
Syntax Description
This command has no arguments or keywords.
Defaults
Forcing packet-level restarts is the default and is necessary for networks that expect this behavior.
Command Modes
Interface configuration
Command History
Examples
The following example disables the link-level restart:
interface serial 3no x25 linkrestartx25 loc
To set the lowest outgoing-only virtual circuit (VC) number, use the x25 loc interface configuration command.
x25 loc circuit-number
Syntax Description
Defaults
0
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Examples
The following example sets a valid outgoing-only virtual circuit range of 2000 to 2005:
interface serial 0x25 loc 2000x25 hoc 2005Related Commands
x25 ltc
To set the lowest two-way virtual circuit (VC) number, use the x25 ltc interface configuration command.
x25 ltc circuit-number
Syntax Description
Defaults
1
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Examples
The following example sets a valid two-way virtual circuit range of 5 to 25:
interface serial 0x25 ltc 5x25 htc 25Related Commands
x25 map
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]
no x25 map protocol address x121-address
Syntax Description
protocol
Protocol type, entered by keyword. Supported protocols are entered by keyword, as listed in Table 72. 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 73.
Defaults
No LAN protocol-to-remote host mapping is set up.
Command Modes
Interface configuration
Command History
Usage Guidelines
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.)
Note
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 72 lists the protocols supported by X.25.
Table 72 Protocols Supported by X.25
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
1 Bridging traffic is supported only for Cisco's traditional encapsulation method, so a bridge map cannot specify other protocols.
2 Packet Assembly/Disassembly (PAD) maps are used to configure session and protocol translation access, therefore, this protocol is not available for multiprotocol encapsulation.
3 Qualified Logical Link Control (QLLC) is not available for multiprotocol encapsulation.
Note
Table 73 lists the map options supported by X.25 using the x25 map command.
Examples
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 0x25 map ip 171.20.2.5 000000010300 broadcastThe following example specifies an ROA name to be used for originating connections:
x25 roa green_list 23 35 36interface serial 0x25 map ip 172.20.170.26 10 roa green_listThe following example specifies a network user ID (NUID) facility to send on calls originated for the address map:
interface serial 0x25 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.
Related Commands
x25 map bridge
To configure an Internet-to-X.121 address mapping for bridging of packets in X.25 frames, use the x25 map bridge interface configuration command.Use the no form of this command to disable the Internet-to-X.121 address mapping.
x25 map bridge x121-address broadcast [option]
Syntax Description
x121-address
The X.121 address.
broadcast
Required keyword for bridging over X.25.
option
(Optional) Services that can be added to this map (same options as the x25 map command). See Table 74 for more details.
Defaults
No bridging over X.25 is configured.
Command Modes
Interface configuration
Command History
Usage Guidelines
The X.25 bridging software uses the same spanning-tree algorithm as the other bridging functions, but allows packets to be encapsulated in X.25 frames and transmitted across X.25 media. This command specifies IP-to-X.121 address mapping and maintains a table of both the Ethernet and X.121 addresses.
Examples
The following example configures transparent bridging over X.25 between two Cisco routers using a maximum of six virtual circuits:
interface serial 1x25 map bridge 000000010300 broadcast nvc 6Related Commands
Sets up the LAN protocols-to-remote host mapping.
x25 address
Sets the X.121 address of a particular network interface.
x25 map cmns
The enhanced x25 route command replaces the x25 map cmns command. Refer to the description of the x25 route command for more information.
x25 map compressedtcp
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]]]
x121-address [option]no x25 map compressedtcp address [protocol2 address2 [...[protocol9 address9]]]
x121-addressSyntax Description
ip-address
IP address.
protocol
(Optional) Protocol type, entered by keyword. Supported protocols are entered by keyword, as listed in Table 72. 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 73 earlier in this chapter.
Defaults
No mapping is configured.
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Note
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.
Examples
The following example establishes a map for TCP/IP header compression on serial interface 4:
interface serial 4ip tcp header-compressionx25 map compressedtcp 172.20.2.5 000000010300Related Commands
x25 map pad
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]
Syntax Description
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 73 earlier in this chapter).
Defaults
No specific options are used for PAD access.
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Examples
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 1x25 pad-accessx25 map pad 000000010300 nuid johndoe secretRelated Commands
Sets up the LAN protocols-to-remote host mapping.
Causes the PAD software to accept PAD connections only from statically mapped X.25 hosts.
x25 modulo
To set the window modulus, use the x25 modulo interface configuration command.
x25 modulo modulus
Syntax Description
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.
Defaults
8
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Examples
The following example sets the window modulus to 128:
interface serial 0x25 modulo 128Related Commands
x25 nvc
To specify the maximum number of virtual circuits (VCs) that a protocol can have open simultaneously to one host, use the x25 nvc interface configuration command. To increase throughput across networks, you can establish up to eight virtual circuits to a host and protocol.
x25 nvc count
Syntax Description
Defaults
1
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Note
Examples
The following example sets the default maximum number of VCs that each map can have open simultaneously to 4:
interface serial 0x25 nvc 4x25 ops
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
Syntax Description
Defaults
128 bytes
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Note
Examples
The following example sets the default maximum packet sizes to 512:
interface serial 1x25 ips 512x25 ops 512Related Commands
Sets the interface default maximum input packet size to match that of the network.
x25 pad-access
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-access
no x25 pad-access
Syntax Description
This command has no arguments or keywords.
Defaults
Accept PAD connections from any host.
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Examples
The following example restricts incoming PAD access on the interface to attempts from the host with the X.121 address 000000010300:
interface serial 1x25 pad-accessx25 map pad 000000010300Related Commands
x25 pvc (encapsulating)
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
[option]no x25 pvc circuit
Syntax Description
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 75. 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 76.
Defaults
None. The PVC window and maximum packet sizes default to the interface default values.
Command Modes
Interface configuration
Command History
Usage Guidelines
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 75 lists supported protocols.
Table 75 Protocols Supported by X.25 PVCs
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
1 Bridging traffic is supported only for Cisco's traditional encapsulation method, so a bridge PVC cannot specify other protocols.
2 QLLC is not available for multiprotocol encapsulation.
Table 76 lists supported X.25 PVC options.
Examples
The following example establishes a PVC on channel 2 to encapsulate VINES and IP with the far host:
interface serial 0x25 ltc 5x25 pvc 2 vines 60002A2D:0001 ip 172.20.170.91 11110001Related Commands
x25 pvc (switched)
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]
Syntax Description
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 77.
Defaults
None. The PVC window and maximum packet sizes default to the interface default values.
Command Modes
Interface configuration
Command History
Usage Guidelines
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 77 lists the switched PVC options supported by X.25.
Examples
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 0encapsulation x25x25 ltc 5x25 pvc 1 interface serial 1 pvc 1interface serial 1encapsulation x25x25 ltc 5x25 pvc 1 interface serial 0 pvc 1x25 pvc (switched PVC to SVC)
To configure a switched permanent virtual circuit (PVC) to switched virtual circuit (SVC) circuit for a given interface, use the switched PVC to SVC version of the x25 pvc interface configuration command.
x25 pvc number1 svc x121-address [flow-control-options] [call-control-options]
Syntax Description
number1
Logical channel ID of the PVC. Value must be lower than any range of circuit numbers defined for SVCs.
svc
Specifies a SVC type.
x121-address
Destination X.121 address for opening an outbound SVC and source X.121 address for matching an inbound SVC.
flow-control-options
(Optional) Adds certain features to the mapping specified. It can be any of the options listed in Table 78.
call-control-options
(Optional) Adds certain features to the mapping specified. It can be any of the options listed in Table 79.
Defaults
None. 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.
Command Modes
Interface configuration
Command History
Usage Guidelines
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 78 lists the flow control options supported by X.25 during PVC to SVC switching.
Table 79 lists the call control options supported by X.25 during PVC to SVC switching.
Examples
The following example configures PVC to SVC switching between two serial interfaces:
x25 routinginterface serial0encapsulation x25x25 address 201700x25 ltc 128x25 idle 2interface serial2encapsulation x25 dcex25 address 101702x25 route ^20 interface serial0x25 route ^10 interface serial2interface serial0x25 pvc 5 svc 101601 packetsize 128 128 windowsize 2 2 no-incomingx25 pvc 6 svc 101602 packetsize 128 128 windowsize 2 2 no-outgoing idle 0x25 pvc 7 svc 101603 packetsize 128 128 windowsize 2 2Any 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.
x25 pvc (XOT)
To connect two permanent virtual circuits (PVCs) across a TCP/IP LAN, use the X.25-over-TCP (XOT) service form of the x25 pvc interface configuration command.
x25 pvc number1 xot address interface serial string pvc number2 [option]
Syntax Description
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 80.
Defaults
None. The PVC window and packet sizes default to the interface default values.
Command Modes
Interface configuration
Command History
Usage Guidelines
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 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, the XOT 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 80 lists the PVC tunnel options supported by X.25.
Examples
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-inservice tcp-keepalives-outinterface serial 0x25 pvc 1 xot 172.20.1.2 interface serial 1 pvc 2The following example enters the parameters for one side of a connection destined for the Cisco 7000 series with RSP7000:service tcp-keepalives-inservice tcp-keepalives-outinterface serial 0x25 pvc 1 xot 172.20.1.2 interface serial 1/1 pvc 2See the section "X.25 and LAPB Configuration Examples" in the Wide-Area Networking Configuration Guide for more complete configuration examples.
Related Commands
x25 remote-red
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
Syntax Description
Defaults
No table is set up.
Command Modes
Interface configuration
Command History
Usage Guidelines
The table that results from this command provides the address translation information the router sends to the BFE when it is in emergency mode.
Examples
The following example sets up a short table of BFE nodes for serial interface 0:
interface serial 0x25 remote-red 172.20.9.3 remote-black 172.20.9.13x25 remote-red 192.108.15.1 remote-black 192.108.15.26Related Commands
x25 roa
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
no x25 roa name
Syntax Description
Defaults
No packet network carriers are specified.
Command Modes
Global configuration
Command History
Usage Guidelines
This command specifies a list of transit ROAs to use, referenced by name.
Examples
The following example sets an ROA name and then sends the list via the X.25 user facilities:
x25 roa green_list 23 35 36interface serial 0x25 facility roa green_listx25 map ip 172.20.170.26 10 roa green_listRelated Commands
Forces facilities on a per-call basis for calls originated by the router (switched calls are not affected).
Sets up the LAN protocols-to-remote host mapping.
x25 route
To create an entry in the X.25 routing table (to be consulted for forwarding incoming calls and for placing outgoing packet assembler/disassembler (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-options] [modification-options] disposition-options [xot-keepalive-options]
no x25 route [#position] [selection-options] [modification-options] disposition-options [xot-keepalive-options]
Syntax Description
#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 value for the position argument is given, the entry is appended to the end of the routing table.
selection-options
(Optional) The selection options identify when the subsequent modification and disposition options apply to an X.25 call; any or all variables may be specified for a route. For selection keyword and argument options, see Table 81 in the "Usage Guidelines" section.
For selection and modification pattern and character matching and replacement see Table 83, Table 84, and Table 85 in the "Usage Guidelines" section.
Although each individual selection criterion is optional, at least one selection or modification option must be specified in the x25 route command.
modification-options
(Optional) The modification options modify 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. For modification keyword and argument options, see Table 82 in the "Usage Guidelines" section.
For selection and modification pattern and character matching and replacement see Table 83, Table 84, and Table 85 in the "Usage Guidelines" section.
Although each individual modification is optional, at least one selection or modification option must be specified in the x25 route command.
disposition-options
Specifies the disposition of a call matching the specified selection pattern. For disposition keyword and argument options, see Table 86 in the "Usage Guidelines" section.
xot-keepalive-options
(Optional) The XOT-keepalive options specify an X.25 over TCP (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 sent data goes unacknowledged for a given number of attempts over a period of time. For XOT-keepalive keyword and argument options, see Table 87 in the "Usage Guidelines" section.
Defaults
No entry is created in the X.25 routing table.
Command Modes
Global configuration
Command History
11.3
The following selection option keywords and arguments were added:
•
•
•
In prior releases, CMNS routing information was implied by maps defining a network service access point (NSAP) prefix for a CMNS host's Media Access Control (MAC) address.
The clear interface disposition option keyword and argument was introduced. In prior releases, the disposition was implicit in a route to the Null 0 interface.
12.0(5)T
The dns keyword followed by pattern argument (see Table 85) was added (for the DNS-Based X.25 Routing feature) to be used after the xot in the x25 route destination-pattern xot command.
Usage Guidelines
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 modification options are long-standing but newly applicable to all dispositions in Cisco IOS Release 11.3 and later.
Note
Selection Options
Selection arguments 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 81 lists the selection options for the x25 route command. At least one selection or modification option must be specified.
Note
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 Data Network Identification Code (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.
Modification Options
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 82 lists the modification options for the x25 route command. At least one selection or modification option must be specified.
Table 82 x25 route Modification Options
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 83 and Table 84 for summaries of pattern and character matching, respectively. See Table 85 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 83 and Table 84 for summaries of pattern and character matching, respectively. See Table 85 for a summary of pattern rewrite elements.
Note
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.
Pattern and Character Matching and Replacement for Selection and Modification Options
Refer to Table 83, Table 84, and Table 85 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 publication.
Table 83 Pattern Matching for x25 route Selection and Modification Options
*
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
1 Precede the question mark with Ctrl-V to prevent the question mark from being interpreted as a help command.
Disposition Option
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.
Using the continue keyword provides flexibility by reducing the number of X.25 route configurations necessary in the route table by breaking them into separate, simpler, and more manageable tasks. It allows the x25 route command to cumulatively hold all specified route entries and carry whatever selection or modification options you may have just specified on the command line. The route table lookup terminates when a matching route is found among the remaining entries in the route table. The continue disposition must be the last option on the x25 route command line.
Table 86 lists the disposition options for the x25 route command. You must select one of these options.
Table 86 x25 route Disposition Options
interface interface number dlci number
(Optional) Routes the X.25 call to the specified Annex G link. You must include the interface number and enter the data link connection identifier (DLCI) number. You only need to do this if you want the router to accept switched calls, as well as originate them.
interface cmns-interface mac mac-address
Routes 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 Fiber Distributed Data Interface (FDDI). The interface numbering scheme depends on the router interface hardware.
xot ip-address [ip2-address [...[ip6-address]]] [xot-source interface]
Routes 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.
xot dns pattern
Used with the DNS for X.25 feature, this option consults the DNS to get up to six destination IP addresses using whatever lookup pattern you choose (see Table 85).
hunt-group name
Routes the selected call to the X.25 hunt group. The chosen route may vary depending on the hunt group configuration.
clear
Terminates the call.
XOT Keepalive Options
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 87 lists and describes the xot-keepalive options for the x25 route command.
X.25 Routing Action when a Match Is Found
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.
Examples
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 0The following Annex G example routes the X.25 call to the specified Annex G DLCI link. You must include both interface number and DLCI number. It is this combination of both these numbers that indicates the logical X.25 interface over Frame Relay.
x25 route ^2222 interface serial 1 dlci 20The following example prevents X.25 routing for calls that do not specify a source address:
x25 route source ^$ clearThe 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 172.20.2.5 172.20.7.10 172.10.7.9The following example clears calls that contain a 3 in the source address. The disposition keyword clear is new.
x25 route source 3 clearThe following example clears calls that contain 33 in the source address:
x25 route source 33 clearThe following example clears a call to the destination address 9999:
x25 route ^9999$ clearThe 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 0The 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 172.21.53.61The following DNS-based X.25 routing example shows an X.25 request to the DNS. The \0 pattern indicates that the entire incoming X.121 address is being used as the index into the DNS, which will return the required IP address.
x25 route ^.* xot dns \0The following example routes calls containing the destination extension address preamble 11.1234:
x25 route dest-ext ^11.1234.* interface serial 0The following example rewrites the destination address as 9999. There must be a minimum of four 8s in the address. (8888888 will change to 9999.)
x25 route 8888 substitute-dest 9999 interface serial 0The 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 0The 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 0The 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 0The following example of the Calling Address Insertion based on the Input Interface feature strips the destination address off a call coming from the X.25 (serial 0) network with a destination address beginning with 02 and ending in anything, replaces it with a network-assigned address of \1, and forwards it to the substitute destination of interface serial 2:
x25 route ^02(.*) input-interface serial 0 substitute-destination \1 interface serial 2The following example of the Calling Address Insertion based on the Input Interface feature inserts a 2 to the source address of any call coming from serial 2 and forwards the call to serial 0:
x25 route ^02 input-interface serial 2 substitute-source 2\0 interface serial 0The following example rewrites the source address based on 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 0The 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 0Related Commands
x25 routing
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 [tcp-use-if-defs]
no x25 routing
Syntax Description
Defaults
Disabled
Command Modes
Global configuration
Command History
Usage Guidelines
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 tcp-use-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 tcp-use-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.
Examples
The following example enables X.25 switching:
x25 routingx25 suppress-called-address
To omit the destination address in outgoing calls, use the x25 suppress-called-address interface configuration command. To reset this command to the default state, use the no form of this command.
x25 suppress-called-address
no x25 suppress-called-address
Syntax Description
This command has no arguments or keywords.
Defaults
The called address is sent.
Command Modes
Interface configuration
Command History
10.0
This command was introduced.
11.3
This command was modified to include PAD calls.
Usage Guidelines
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.
Examples
The following example suppresses or omits the called address in Call Request packets:
interface serial 0x25 suppress-called-addressx25 suppress-calling-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-address
no x25 suppress-calling-address
Syntax Description
This command has no arguments or keywords.
Defaults
The calling address is sent.
Command Modes
Interface configuration
Command History
10.0
This command was introduced prior to this release.
11.3
This command was modified to include PAD calls.
Usage Guidelines
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.
Examples
The following example suppresses or omits the calling address in Call Request packets:
interface serial 0x25 suppress-calling-addressx25 t10
Use the x25 t10 interface configuration command to set the value of the Restart Indication retransmission timer (T10) on DCE devices.
x25 t10 seconds
Syntax Description
Defaults
60 seconds
Command Modes
Interface configuration
Command History
Examples
The following example sets the T10 timer to 30 seconds:
interface serial 0x25 t10 30x25 t11
To set the value of the Incoming Call timer (T11) on DCE devices, use the x25 t11 interface configuration command.
x25 t11 seconds
Syntax Description
Defaults
180 seconds
Command Modes
Interface configuration
Command History
Examples
The following example sets the T11 timer to 90 seconds:
interface serial 0x25 t11 90x25 t12
To set the value of the Reset Indication retransmission timer (T12) on DCE devices, use the x25 t12 interface configuration command.
x25 t12 seconds
Syntax Description
Defaults
60 seconds
Command Modes
Interface configuration
Command History
Examples
The following example sets the T12 timer to 30 seconds:
interface serial 0x25 t12 30x25 t13
To set the value of the Clear Indication retransmission timer (T13) on DCE devices, use the x25 t13 interface configuration command.
x25 t13 seconds
Syntax Description
Defaults
60 seconds
Command Modes
Interface configuration
Command History
Examples
The following example sets the T13 timer to 30 seconds:
interface serial 0x25 t13 30x25 t20
To set the value of the Restart Request retransmission timer (T20) on DTE devices, use the x25 t20 interface configuration command.
x25 t20 seconds
Syntax Description
Defaults
180 seconds
Command Modes
Interface configuration
Command History
Examples
The following example sets the T20 timer to 90 seconds:
interface serial 0x25 t20 90x25 t21
To set the value of the Call Request timer (T21) on DTE devices, use the x25 t21 interface configuration command.
x25 t21 seconds
Syntax Description
Defaults
200 seconds
Command Modes
Interface configuration
Command History
Examples
The following example sets the T21 timer to 100 seconds:
interface serial 0x25 t21 100x25 t22
To set the value of the Reset Request retransmission timer (T22) on DTE devices, use the x25 t22 interface configuration command.
x25 t22 seconds
Syntax Description
Defaults
180 seconds
Command Modes
Interface configuration
Command History
ExamplesL
The following example sets the T22 timer to 90 seconds:
interface serial 0x25 t22 90x25 t23
To set the value of the Clear Request retransmission timer (T23) on DTE devices, use the x25 t23 interface configuration command.
x25 t23 seconds
Syntax Description
Defaults
180 seconds
Command Modes
Interface configuration
Command History
Examples
The following example sets the T23 timer to 90 seconds:
interface serial 0x25 t23 90x25 threshold
This command replaces the longstanding x25 th command. To set the data packet acknowledgment threshold, use the x25 threshold interface configuration command.
x25 threshold delay-count
Syntax Description
delay-count
Value between zero and the input window size. A value of 1 sends one Receiver Ready acknowledgment per packet.
Defaults
0 (which disables the acknowledgment threshold)
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Examples
The following example sends an explicit Receiver Ready acknowledgment when it has received 5 data packets that it has not acknowledged:
interface serial 1x25 threshold 5Related Commands
Changes the default incoming window size to match that of the network.
Changes the default outgoing window size to match that of the network.
x25 use-source-address
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-address
no x25 use-source-address
Syntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration
Command History
Usage Guidelines
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).
Examples
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 0no x25 use-source-addressx25 win
To change the default incoming window size to match that of the network, use the x25 win interface configuration command.
x25 win packets
Syntax Description
Defaults
2 packets
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Note
Examples
The following example specifies that 5 packets may be received before an X.25 acknowledgment is sent:
interface serial 1x25 win 5Related Commands
Sets the window modulus.
Sets the data packet acknowledgment threshold.
Changes the default outgoing window size to match that of the network.
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
Syntax Description
Defaults
2 packets
Command Modes
Interface configuration
Command History
Usage Guidelines
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.
Note
Examples
The following example specifies a default limit of 5 for the number of outstanding unacknowledged packets for virtual circuits:
interface serial 1x25 wout 5Related Commands
Sets the window modulus.
Sets the data packet acknowledgment threshold.
Changes the default incoming window size to match that of the network.
x29 access-list
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
no x29 access-list access-list-number
Syntax Description
Defaults
No access lists are defined.
Command Modes
Global configuration
Command History
Usage Guidelines
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 publication.
The access lists must be applied to a vty with the access-class command.
Examples
The following example permits connections to hosts with addresses beginning with the string 31370:
x29 access-list 2 permit ^31370Related Commands
access-class
Restricts incoming and outgoing connections between a particular vty (into a Cisco device) and the addresses in an access list.
x29 profile
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]
Syntax Description
Defaults
The default PAD profile script is used. The default for inbound connections is:
2:0 4:1 15:0 7:21Command Modes
Global configuration
Command History
Usage Guidelines
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.
Note
Examples
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 15:1To 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 4:0Related Commands
