Document ID: 12351
Contents
Introduction
Before You Begin
Conventions
Prerequisites
Components Used
Configure
Network Diagram
Configurations
Verify
Troubleshoot
Related Information
Introduction
The behavior of the Data Link Switching (DLSw) backup peer has changed from Cisco IOS® Software version 11.1. Prior to this version, the backup peer connection was torn down as soon as the primary peer became available. All the circuits across the backup peer then had to re-establish across the primary peer, resulting in end users losing their sessions.
The previous DLSw backup peer behavior could also cause the sessions to toggle up and down if instabilities in the network caused the primary peer connection to flap.
To overcome this, Cisco IOS Software release 11.1 introduced the linger parameter on the dlsw remote-peer backup command. If linger=x is specified (where x ranges from 0 to 1440 minutes), the backup peer remains connected for x minutes, after the primary peer connection is re-established, before it gets torn down. This time can be set for a duration long enough to prevent the connection from flapping unnecessarily.
If x=0, the peer behaves exactly as it it did in releases prior to software release 11.1 code. In prior releases, the backup peer connection is torn down immediately once the primary peer is restored. If the linger parameter is not specified, the backup peer connection remains up indefinitely as long as there are circuits using it. Any new circuits, however, are established using the primary peer.
Thelinger parameter is as follows (where the linger value is expressed in minutes):
dlsw remote-peer 0 tcp ip address of backup peer backup-peer ip address of primary linger 0-1440
Before You Begin
Conventions
For more information on document conventions, see the Cisco Technical Tips Conventions.
Prerequisites
There are no specific prerequisites for this document.
Components Used
The information in this document is based on the software and hardware versions below.
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Two Cisco 2504s running Cisco IOS Software version 12.0(7)T.
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Cisco 7206 running 12.1(5)T1.
Note: Cisco IOS Software versions 11.1 and later should support this feature.
The information presented in this document was created from devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If you are working in a live network, ensure that you understand the potential impact of any command before using it.
Configure
In this section, you are presented with the information to configure the features described in this document.
Note: To find additional information on the commands used in this document, use the Command Lookup Tool (registered customers only) .
Network Diagram
This document uses the network setup shown in the diagram below.
Note: FEP and Plesio are not strictly relevant for the DLSw configuration. They are, however, used to provide the mainframe connectivity and generation of DLSw traffic though the Downstream Physical Unit (DSPU), respectively.
Configurations
The relevant parts of all the router configurations are shown below. Note that the dialer-list is set up to define only DLSW as interesting traffic, (port number 2065). Only DLSw traffic brings up the ISDN connection. If you prioritize within DLSw, it would also be necessary to specify port numbers 1981,1982, and 1983 as interesting traffic. Also, note the floating static routes in Tanius and Tatiasaurus pointing to the remote peer address through the Basic Rate Interface (BRI).
In this example, the backup router is Tanius while the primary peer router is Diplodocus. This is accomplished by issuing the configuring dlsw remote-peer 0 tcp 10.64.3.99 backup-peer 10.64.3.97 command on Tatiasaurus. Notice the use of the dlsw remote-peer 0 tcp 10.3.3.1 command on Diplodocus, while Tanius is running in promiscuous mode, dlsw local-peer peer-id 10.64.3.99 promiscuous.
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FEP |
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version 12.1 service timestamps debug datetime service timestamps log datetime no service password-encryption ! hostname FEP ! ! microcode CIP flash slot0:cip27-8.bin microcode reload ! source-bridge ring-group 60 ! ! interface TokenRing0/1 ip address 10.64.3.98 255.255.255.240 no ip route-cache cef no ip mroute-cache ring-speed 16 source-bridge 500 1 60 source-bridge spanning ! ! ! interface Channel5/0 no ip address no keepalive csna 0100 40 ! interface Channel5/1 no ip address no keepalive shutdown ! interface Channel5/2 no ip address lan TokenRing 0 source-bridge 600 1 60 adapter 0 4000.0000.0001 ! router eigrp 1 network 10.0.0.0 ! ! line con 0 exec-timeout 0 0 transport input none line aux 0 line vty 0 4 exec-timeout 0 0 password cisco login ! end |
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Diplodocus |
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version 12.1 no service single-slot-reload-enable no service pad service timestamps debug datetime msec service timestamps log datetime msec no service password-encryption ! hostname diplodocus ! source-bridge ring-group 1 dlsw local-peer peer-id 10.64.3.97 dlsw remote-peer 0 tcp 10.3.3.1 ! ! interface Serial1/0 ip address 10.1.1.1 255.255.255.0 no ip route-cache no ip mroute-cache ! ! interface TokenRing5/0 ip address 10.64.3.97 255.255.255.240 no ip route-cache no ip mroute-cache ring-speed 16 source-bridge 500 1 1 source-bridge spanning ! ! ! router eigrp 1 network 10.0.0.0 auto-summary no eigrp log-neighbor-changes ! ! line con 0 exec-timeout 0 0 transport input none line aux 0 line vty 0 4 password cisco login end |
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Tanius |
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Current configuration: ! version 12.0 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname tanius ! ! username tatiasaurus password 0 cisco ! ! ! ! ip subnet-zero ! isdn switch-type basic-ts013 isdn voice-call-failure 0 cns event-service server ! source-bridge ring-group 8 dlsw local-peer peer-id 10.64.3.99 promiscuous ! ! interface Serial0 no ip address no ip directed-broadcast no ip mroute-cache shutdown no fair-queue ! interface Serial1 no ip address no ip directed-broadcast encapsulation sdlc no keepalive shutdown ! interface TokenRing0 ip address 10.64.3.99 255.255.255.240 no ip directed-broadcast ring-speed 16 source-bridge 500 1 8 ! interface BRI0 ip address 10.2.2.1 255.255.255.0 no ip directed-broadcast encapsulation ppp dialer map ip 10.2.2.2 name tatiasaurus broadcast dialer-group 1 isdn switch-type basic-ts013 ppp authentication chap ! router eigrp 1 network 10.0.0.0 ! ip classless ip route 10.3.3.1 255.255.255.255 10.2.2.2 150 no ip http server ! access-list 100 deny eigrp any any access-list 100 permit tcp any eq 2065 any access-list 100 permit tcp any any eq 2065 dialer-list 1 protocol ip list 100 ! ! line con 0 exec-timeout 0 0 transport input none line aux 0 line vty 0 4 login ! end |
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Tatiasaurus |
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Current configuration: ! version 12.0 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname tatiasaurus ! ! username tanius password 0 cisco ! ! ! ! ip subnet-zero ! isdn switch-type basic-ts013 isdn voice-call-failure 0 cns event-service server ! source-bridge ring-group 1 dlsw local-peer peer-id 10.3.3.1 dlsw remote-peer 0 tcp 10.64.3.97 dlsw remote-peer 0 tcp 10.64.3.99 backup-peer 10.64.3.97 ! ! interface Serial0 ip address 10.1.1.2 255.255.255.0 no ip directed-broadcast no ip mroute-cache clockrate 64000 ! interface Serial1 no ip address no ip directed-broadcast shutdown ! interface TokenRing0 ip address 10.3.3.1 255.255.255.0 no ip directed-broadcast ring-speed 16 source-bridge 20 1 1 source-bridge spanning ! interface BRI0 ip address 10.2.2.2 255.255.255.0 no ip directed-broadcast encapsulation ppp dialer map ip 10.2.2.1 name tanius broadcast 94598140 dialer-group 1 isdn switch-type basic-ts013 ppp authentication chap ! router eigrp 1 network 10.0.0.0 ! ip classless ip route 10.64.3.99 255.255.255.255 10.2.2.1 150 no ip http server ! access-list 100 deny eigrp any any access-list 100 permit tcp any eq 2065 any access-list 100 permit tcp any any eq 2065 dialer-list 1 protocol ip list 100 ! ! line con 0 exec-timeout 0 0 transport input none line aux 0 line vty 0 4 ! end |
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Plesio |
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Current configuration: ! version 12.0 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname plesio ! ! ! ! ! ! ip subnet-zero ! cns event-service server ! source-bridge ring-group 2 ! ! dspu host DPU5 xid-snd 01700005 rmac 4000.0000.0001 rsap 4 lsap 12 ! interface Ethernet0 no ip address no ip directed-broadcast shutdown ! interface Serial0 no ip address no ip directed-broadcast no ip mroute-cache shutdown no fair-queue ! interface Serial1 no ip address no ip directed-broadcast shutdown ! ! interface TokenRing0 no ip address no ip directed-broadcast ring-speed 16 source-bridge 20 1 2 source-bridge spanning dspu enable-host lsap 12 dspu start DPU5 ! ip classless no ip http server ! ! ! line con 0 transport input none line aux 0 line vty 0 4 ! end plesio# |
Verify
The following is an example of output showing the connected backup peer (10.64.3.99) and the active circuit going through it while the primary peer has just come up:
Certain show commands are supported by the Output Interpreter Tool (registered customers only) , which allows you to view an analysis of show command output.
tatiasaurus#show dlsw peer Peers: state pkts_rx pkts_tx type drops ckts TCP uptime TCP 10.64.3.99 CONNECT 2445 2449 conf 0 1 0 19:06:48 TCP 10.64.3.97 CONNECT 11 11 conf 0 0 0 00:04:35 Total number of connected peers: 2 Total number of connections: 2 tatiasaurus#show dlsw cir Index local addr(lsap) remote addr(dsap) state uptime 1912602630 0000.308c.8539(0C) 4000.0000.0001(04) CONNECTED 18:50:11 Total number of circuits connected: 1
The above output shows that the primary peer has come up, however. There is a circuit still connected across the backup peer, and the no linger parameter is specified. This causes the backup peer to remain up.
Now, the circuit across the backup has been disconnected.
tatiasaurus# show dlsw cir
As a result, the backup peer is torn down.
tatiasaurus#show dlsw peer Peers: state pkts_rx pkts_tx type drops ckts TCP uptime TCP 10.64.3.97 CONNECT 20 20 conf 0 0 0 00:09:35 TCP 10.64.3.99 DISCONN 0 0 conf 0 0 - - Total number of connected peers: 1 Total number of connections: 1
There is now no interesting traffic crossing the ISDN. Tthe ISDN connection will be torn down once the idle-timeout value expires. This defaults to 120 seconds, as shown below.
tatiasaurus#show isdn stat Global ISDN Switchtype = basic-ts013 ISDN BRI0 interface dsl 0, interface ISDN Switchtype = basic-ts013 Layer 1 Status: ACTIVE Layer 2 Status: TEI = 64, Ces = 1, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED Layer 3 Status: 1 Active Layer 3 Call(s) Activated dsl 0 CCBs = 1 CCB:callid=801E, sapi=0, ces=1, B-chan=2, calltype=DATA The Free Channel Mask: 0x80000001 Total Allocated ISDN CCBs = 1 tatiasaurus# tatiasaurus#show dialer BRI0 - dialer type = ISDN Dial String Successes Failures Last DNIS Last status 94598140 13 16 19:12:53 successful 0 incoming call(s) have been screened. 0 incoming call(s) rejected for callback. BRI0:1 - dialer type = ISDN Idle timer (120 secs), Fast idle timer (20 secs) Wait for carrier (30 secs), Re-enable (15 secs) Dialer state is idle BRI0:2 - dialer type = ISDN Idle timer (120 secs), Fast idle timer (20 secs) Wait for carrier (30 secs), Re-enable (15 secs) Dialer state is data link layer up Dial reason: ip (s=10.3.3.1, d=10.64.3.99) Time until disconnect 57 secs Connected to 94598140 (tanius) tatiasaurus# 1d00h: %ISDN-6-DISCONNECT: Interface BRI0:2 disconnected from 94598140 tanius, call lasted 6922 9 seconds 1d00h: %LINK-3-UPDOWN: Interface BRI0:2, changed state to down 1d00h: %LINEPROTO-5-UPDOWN: Line protocol on Interface BRI0:2, changed state to down
Any new circuits come up through the primary peer connection as long as the backup remains disconnected.
Troubleshoot
There is currently no specific troubleshooting information available for this configuration.
Related Information
| Updated: Jan 28, 2008 | Document ID: 12351 |