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Cisco IOS Software Releases 12.3 T

Field Notice: FN - 62529 - Cisco IOS SNASwitch - CP-CP Session May Fail After Path Switch Failover to the Backup Network Node Server


Revised September 11, 2008
October 11, 2006

NOTICE:

THIS FIELD NOTICE IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTY OF MERCHANTABILITY. YOUR USE OF THE INFORMATION ON THE FIELD NOTICE OR MATERIALS LINKED FROM THE FIELD NOTICE IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS FIELD NOTICE AT ANY TIME.


Revision History

Revision

Date

Comment

1.1 11-SEP-2008 Added DDTS CSCsr48604 and its relation to the workaround in Workaround/Solution section.

1.0

11-OCT-2006

Initial Public Release

     

Products Affected

Product

Comments

12.3

All images containing SNASwitch feature set

     

Problem Description

Systems Network Architecture Switching Services (SNASwitch) may be unable to restart a control-point-to-control-point (CP-CP) session with its primary network node server (NNS) after a failover to the backup NNS.

This failure can only occur when:

  1. The SNASwitch router is configured to use a connection network virtual routing node (VRN), as indicated by the vnname keyword on the snasw port configuration command.

  2. The same VRN port from #1 above is specified by the port keyword on the snasw link configuration command for the primary NNS link.

Background

The failure described in this field notice is due to an architectural limitation in Cisco IOS. The Bug ID listed above is for reference only. See the Workaround/Solution section below for details on how to avoid the failure condition.

Problem Symptoms

The CP-CP session with the primary NNS fails to restart after a failover to the backup NNS. SNASwitch continues to use the backup NNS after the primary NNS is restored. The failure is indicated by an exception log entry in the pdlog output displayed by the show snasw pdlog EXEC command, as in the following example:

**** EVENT : Link station H#93 activated

**** 00000120 - EXCEPTION 512:121 (0) ****
Unable to start requested CP-CP sessions with adjacent node
 Port name          = IP
 LS name            = H#93
 Adjacent CP name   = EBD1.H#93        
From ../dcl/ncsxidpi.c 319 :at 7:08:11, 14 October 03

This failure condition can also be verified using the show snasw link detail EXEC CLI command for the link to the primary NNS. The command output will show a value of No for CP-CP session support instead of its normal value of Yes .

Workaround/Solution

When the failure condition occurs, the link to the primary NNS will be activated as a VRN link. Since VRN links do not support CP-CP sessions, the only way to restore the CP-CP session to the primary NNS is to issue a snasw stop EXEC CLI command for the link. This may disrupt any logical-unit-to-logical-unit (LU-LU) sessions currently using that link.

To avoid the failure condition, modify the IOS configuration to prevent SNASwitch from ever allowing a configured link to activate as a VRN link.

Note: Cisco has recently discovered a software problem (CSCsr48604) that may be exposed by this workaround. To avoid the failure condition and the software problem, upgrade to an IOS version with the fix for CSCsr48604 before configuring the workaround shown in the example below.

In the example below, the VRN has been moved to its own snasw port configuration command:

snasw cpname NETA.SNASW
snasw port HPRIP hpr-ip Loopback0                     <<< VRN removed
snasw port HPRIP1 hpr-ip Loopback1 vnname NETA.VRN    <<< New port with VRN
snasw port DLSWLINK vdlc 802 mac 4000.7700.5555
snasw link HOST151 port HPRIP ip-dest 10.10.10.1 nns  <<< Link uses non-VRN port 
snasw link HOST135 port HPRIP ip-dest 10.10.20.1      <<< Link uses non-VRN port

You must ensure that all APPN nodes specifying this VRN have IP connectivity to the new Loopback1 interface.

DDTS

To follow the bug ID link below and see detailed bug information, you must be a registered user and you must be logged in.

DDTS

Description

CSCec70672 (registered customers only)

SNASW CP-CP session to Primary NNS fails after path switch failover

CSCsr48604 (registered customers only) SNASwitch accepts CP-CP sessions from second Network Node concurrently

     

For More Information

If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods:

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