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Table Of Contents
X.25 Dual Serial Line Management
Supported Standards, MIBs, and RFCs
Configuring X.25 Dual Serial Line Management
Verifying X.25 Dual Serial Line Management
Monitoring and Maintaining X.25 Dual Serial Line Management
X.25 Dual Serial Line Management Configuration Example
X.25 Dual Serial Line Management
Feature History
This document describes the X.25 Dual Serial Line Management feature in Cisco IOS Release 12.2(13)T. It includes the following sections:
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Supported Standards, MIBs, and RFCs
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Feature Overview
Telco service providers use data communications networks (DCNs) to provide communications between network management applications (also called operations support systems or OSSs) and network elements. The telco DCNs use the X.25 protocol (or a variation of X.25) to send network management information across the DCN.
Figure 1 shows a typical DCN that uses the BX.25 protocol developed by Bell Communications Research (now Telcordia Technologies). The Lucent 5ESS switch in this network uses the BX.25 protocol for monitoring, provisioning and collecting billing data.
Figure 1
Network Management Application Monitors Lucent 5ESS Switch over Datakit Network
The Datakit node provides the communications front end to a network management application and provides two links, SCC0 and SCC1, for link redundancy. One link is active and passes data across the network; the other remains in standby mode.
The Datakit node acts as a transport, so that to the network management application and the Lucent 5ESS switch, the node looks like it has two individual circuits. The network management application host is supplying leads on both interfaces but ignoring Set Asynchronous Balanced Mode (SABM) messages on the standby interface. If communication is lost on the active interface, the network management application host responds to the SABM messages on the standby interface and it becomes the active interface.
In the past, incumbent local exchange carriers (ILECs) have built either Lucent Datakit or X.25 networks to carry the network management data. Large ILEC customers are currently replacing the Lucent Datakit portion of the networks with Cisco IP core routers in their DCN. Figure 2 shows a typical migration path using X.25 over TCP/IP (XOT) and the Cisco Serial Tunneling (STUN) features.
Figure 2
Network Management Application Monitors Lucent 5ESS Switch Using XOT and STUN
Although the solution shown in Figure 2 eliminates some of the Lucent Datakit network elements in ILEC networks, the network still requires a Lucent Datakit node as a front end to the network management application from the Lucent 5ESS switch.
Additionally, competitive local exchange carriers (CLECs) do not have DCNs or have very limited ones. Furthermore, the CLECs are not interested in purchasing the legacy Lucent Datakit solution shown in Figure 1, nor do they want to install a network management application with a Lucent Datakit front end as shown in Figure 2.
Both the CLECs and the ILECs want the DCN based on IP intranet technologies shown in Figure 3.
Figure 3
Network Management Application Monitors Lucent 5ESS Switch over IP Network
As Figure 3 shows, Cisco offers solutions that allow telco service providers to reduce operating costs, translate and migrate existing X.25-based DCNs to IP-based DCNs, and bridge traditional telephony operations to newer ones. The X.25 Dual Serial Line Management feature is a part of the Cisco IOS Telco Feature Set, a bundle of applications specific to the DCN environment. Specifically, this feature supports X.25-to-TCP protocol translation, and provides dual serial interfaces to preserve the redundancy and monitoring capability available from the SCC0 and SCC1 links on the Lucent 5ESS switch in the DCN network.
Benefits
The X.25 Dual Serial Line Management feature provides the following benefits:
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Additionally, the Cisco IOS translate tcp command has been updated with the dynamic keyword for PVC options. The dynamic keyword provides a backup facility for PVC applications. Dynamic PVCs can be made part of an active backup configuration by using the dual serial line management feature.
Restrictions
The X.25 Dual Serial Line Management feature is used in DCN networks utilizing the Lucent 5ESS switch and running the X.25 protocol.
Related Documents
The chapter "Configuring X.25 and LAPB" in the Cisco IOS Wide-Area Networking Configuration Guide, Release 12.2, describes how to configure X.25.
The Cisco protocol translation feature is described in the Cisco IOS Terminal Services Configuration Guide, Release 12.2, in the chapter, "Configuring Protocol Translation and Virtual Asynchronous Devices."
The translate command used for protocol translation is described in the Cisco IOS Terminal Services Command Reference, Release 12.2T.
The section "Switch Monitoring Networks: Cisco X.25 BAI OSS Connectivity Solution" in the "Cisco Network Solutions for the Telco DCN: Telephone Switch Environments" white paper provides tasks and examples for configuring a backup interface using dual serial lines in a telco DCN.
The "X.25 Record Boundary Preservation for Data Communications Networks" feature module provides related information about X.25 Record Boundary Preservation.
Supported Platforms
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Determining Platform Support Through Feature Navigator
Cisco IOS software is packaged in feature sets that support specific platforms. To get updated information regarding platform support for this feature, access Feature Navigator. Feature Navigator dynamically updates the list of supported platforms as new platform support is added for the feature.
Feature Navigator is a web-based tool that enables you to quickly determine which Cisco IOS software images support a specific set of features and which features are supported in a specific Cisco IOS image.
Feature Navigator is updated regularly when major Cisco IOS software releases and technology releases occur. For the most current information, go to the Feature Navigator home page at the following URL:
Supported Standards, MIBs, and RFCs
Standards
None
MIBs
None
To obtain lists of supported MIBs by platform and Cisco IOS release, and to download MIB modules, go to the Cisco MIB website on Cisco.com at the following URL:
http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml
RFCs
None
Configuration Tasks
See the following sections for the configuration tasks for the X.25 Dual Serial Line Management feature. Each task in the list is identified as either required or optional:
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Configuring X.25 Dual Serial Line Management
To configure the X.25 Dual Serial Line Management feature, you must configure dual serial lines running the X.25 protocol, and activate a backup function on one of the interfaces. To enter these configurations, use the following commands beginning in global configuration mode:
Refer to the documents listed in the "Related Documents" section for additional configuration information. The section "X.25 Dual Serial Line Management Configuration Example" also lists commands that you might enter to configure X.25 and X.25-to-TCP protocol translation.
Verifying X.25 Dual Serial Line Management
The verification process described in this section is based on the following configuration:
!interface Serial0/0description connects to X.25 switchip address 10.10.0.15 255.255.255.0encapsulation x25 dcebackup active interface Serial0/1x25 ltc 10clockrate 64000To verify correct operation of the X.25 Dual Serial Line Management feature, perform the following steps in EXEC mode:
Step 1
Router# show backupPrimary Interface Secondary Interface Status----------------- ------------------- ------Serial0/0 Serial0/1 active backupStep 2
Router# show interfaces s0/1Serial0/1 is up, line protocol is upHardware is PowerQUICC SerialDescription: connects to X.25 switchInternet address is 10.10.0.30/24Backup interface Serial0/0, failure delay 0 sec, secondary disabledelay 0 sec,kickin load not set, kickout load not setMTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,reliability 255/255, txload 1/255, rxload 1/255Encapsulation X25, loopback not setX.25 DCE, address 3034, state R1, modulo 8, timer 0Defaults: idle VC timeout 0cisco encapsulationinput/output window sizes 2/2, packet sizes 128/128Timers: T10 60, T11 180, T12 60, T13 60Channels: Incoming-only none, Two-way 10-1024, Outgoing-only noneRESTARTs 2/0 CALLs 4+0/2+0/0+0 DIAGs 0/0LAPB DCE, state CONNECT, modulo 8, k 7, N1 12056, N2 20T1 3000, T2 0, interface outage (partial T3) 0, T4 0VS 1, VR 1, tx NR 1, Remote VR 1, Retransmissions 0Queues: U/S frames 0, I frames 0, unack. 0, reTx 0IFRAMEs 130/130 RNRs 0/0 REJs 0/0 SABM/Es 2/1 FRMRs 0/0 DISCs 0/0Last input never, output 1w3d, output hang neverLast clearing of "show interface" counters 2w2dQueueing strategy: fifoOutput queue 0/40, 0 drops; input queue 0/75, 0 drops5 minute input rate 0 bits/sec, 0 packets/sec5 minute output rate 0 bits/sec, 0 packets/sec242 packets input, 4224 bytes, 0 no bufferReceived 0 broadcasts, 0 runts, 0 giants, 0 throttles2 input errors, 0 CRC, 2 frame, 0 overrun, 0 ignored, 0 abort183 packets output, 1337 bytes, 0 underruns0 output errors, 0 collisions, 131 interface resets0 output buffer failures, 0 output buffers swapped out5 carrier transitionsDCD=up DSR=up DTR=up RTS=up CTS=up
Troubleshooting Tips
To troubleshoot operation of the X.25 Dual Serial Line Management feature, use the debug backup privileged EXEC command.
Monitoring and Maintaining X.25 Dual Serial Line Management
To monitor and maintain the X.25 Dual Serial Line Management feature, use the commands and steps listed in the "Verifying X.25 Dual Serial Line Management" section.
X.25 Dual Serial Line Management Configuration Example
In the following example, dual serial lines (serial 1/6 and 1/7) are configured for the X.25 protocol. Serial interface 1/6 is configured as the primary interface, and serial interface 1/7 is configured as the backup interface. X.25-to-TCP protocol translation is also configured.
interface Serial1/6description SCC0backup active interface serial 1/7encapsulation x25 dcex25 address 66666666x25 ltc 8x25 ips 256x25 ops 256clockrate 9600!interface Serial1/7description SCC1encapsulation x25 dcex25 address 66666666x25 ltc 8x25 ips 256x25 ops 256clockrate 9600!x25 route ^66666666 interface Serial1/6x25 route ^66666666 interface Serial1/7!translate tcp 172.20.21.188 port 1025 x25 66666666 pvc 1 dynamic max-users 1translate tcp 172.20.21.188 port 1026 x25 66666666 pvc 2 dynamic max-users 1translate tcp 172.20.21.188 port 1027 x25 66666666 pvc 3 dynamic max-users 1translate tcp 172.20.21.188 port 1028 x25 66666666 pvc 4 dynamic max-users 1translate tcp 172.20.21.188 port 1029 x25 66666666 pvc 5 dynamic max-users 1translate tcp 172.20.21.188 port 1030 x25 66666666 pvc 6 dynamic max-users 1translate tcp 172.20.21.188 port 1031 x25 66666666 pvc 7 dynamic max-users 1Command Reference
This section documents the new X.25 Dual Serial Line Management feature commands. All other commands used with this feature are documented in the Cisco IOS Release 12.2 command reference publications.
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backup active interface
To activate primary and backup lines on specific X.25 interfaces, use the backup active interface command in interface configuration mode. To disable active backup behavior on the X.25 interface, use the no form of this command.
backup active interface X.25-interface number
no backup active interface X.25-interface number
Syntax Description
Defaults
No default behavior or values.
Command Modes
Interface configuration
Command History
Usage Guidelines
The backup active interface command is only available on serial interfaces configured for the X.25 protocol. Use this command to activate dual serial lines (a primary and a backup) to maintain the redundancy and monitoring capability available from the SCC0 and SCC1 links on a Lucent 5ESS switch in a telco data communication network (DCN). The DCN provides telco service providers with communications for network management applications.
This configuration requires that both serial interfaces be on the same Cisco router. Once the backup active interface command is configured, the router will bring up leads on the backup X.25 interface, but will ignore Set Asynchronous Balanced Mode (SABM) messages from the Lucent 5ESS switch until the primary interface fails.
Examples
The following partial example shows how to configure a primary and backup X.25 interface for dual serial line management of the Lucent 5ESS switch in a DCN:
interface serial 1/0description SCC0backup active interface serial 1/1encapsulation x25 dcex25 address 66666666x25 ltc 8x25 ips 256x25 ops 256clockrate 9600!interface serial 1/1description SCC1encapsulation x25 dcex25 address 66666666x25 ltc 8x25 ips 256x25 ops 256clockrate 9600...Related Commands
debug backup
Monitors the transitions of an interface going down then back up.
show backup
Displays interface backup status.
debug backup
To monitor the transitions of an interface going down then back up, use the debug backup command in privileged EXEC mode. To disable this transition report, use the no form of this command.
debug backup
no debug backup
Syntax Description
This command has no arguments or keywords.
Defaults
No default behavior or values.
Command Modes
Privileged EXEC
Command History
Usage Guidelines
The debug backup command is useful for monitoring dual X.25 interfaces configured as primary and backup in a telco data communication network (DCN).
Examples
The following example shows how to start the debug backup command:
Router# debug backupRelated Commands
backup active interface
Activates primary and backup lines on specific X.25 interfaces.
show backup
Displays interface backup status.
show backup
To display interface backup status, use the show backup command in EXEC mode.
show backup
Syntax Description
This command has no arguments or keywords.
Defaults
No default behavior or values.
Command Modes
EXEC
Command History
12.0
This command was introduced.
12.2(13)T
This command was enhanced to show primary and secondary interfaces configured as backup interfaces.
Usage Guidelines
Use the show backup command to display the status of backup interfaces. This command is especially useful when dual serial X.25 interfaces are configured as primary and backup in a telco data communication network (DCN).
Examples
The following example shows a typical display from the show backup command:
Router# show backupPrimary Interface Secondary Interface Status----------------- ------------------- ------Serial0/0 Serial0/1 active backupRelated Commands
backup active interface
Activates primary and backup lines on specific X.25 interfaces.
debug backup
Monitors the transitions of an interface going down then back up.
Glossary
data communications network—See DCN.
DCN—data communications network. An out-of-band network that provides connectivity between network elements and their respective operations support system (OSS). Its primary function is enabling the surveillance and the status of a telco network, yet it also facilitates network operations and management functions such as provisioning, billing, planning, and service assurance.
CLEC—competitive local exchange carrier. Company that builds and operates communication networks in metropolitan areas and provides its customers with an alternative to the local telephone company.
competitive local exchange carrier—See CLEC.
ILEC— incumbent local exchange carrier. The local telephone company that controls the cable that makes up the telephone network.
incumbent local exchange carrier—See ILEC.
Lucent 5ESS switch—A Class 5 local telephony switch that connects a local subscriber to a telephone network.
network element—A single piece of telecommunications equipment used to perform a function or service integral to the underlying network.
network management application—A application for managing elements in a service providers' network. For a Class 5 local telephony switch, the applications are used monitor the switch, provision the switch, collect call detail records, and collect traffic data. Examples of these applications include an OSS such as Lucent's Network Fault Management (NFM) application and Telcordia Technologies' Network Monitoring and Assurance (NMA) System.
operations support system—See OSS.
OSS—operations support system. DCN network management and operations applications.
SABM—Set Asynchronous Balanced Mode. Link Access Procedure, Balanced (LAPB) data link layer message that sets the operational mode of a link.
Set Asynchronous Balanced Mode—See SABM.
telco—Abbreviated form of the two words "telephone company."
X.25 protocol—ITU-T standard that defines how connections between data terminal equipment and data communications equipment are maintained for remote terminal access and computer communications in a network.
