Troubleshooting a group-interface (LACP port-channel) for partner ID and state changes.

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Article ID: 167784

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Updated On:

Products

XOS

Issue/Introduction

Troubleshooting a group-interface (LACP port-channel) for partner ID and state changes.If there is a scenario where there is group-interface interface flapping (LACP link status going down/up), you may want to monitor the partner ID and state changes.

Cause

Flapping LACP group-interfaces can be difficult to troubleshoot, especially if the issues are happening intermittently.  One way to do this is to use the attached script which runs a 'vethcfg list' every 2 seconds and pipes the output to a file on the APM.  This can be helpful to aggressively watch the for state changes on a group interface including partner ID changes, MUX state, and LACP BPDU status.

Resolution

In order to use this troubleshooting method you will need to do the following.

Create the veth_script.sh in the /tftpboot/<vap-group_index>/root/ directory of an APM participating in the group-interface.  Make the file executable.

1.  Create the file:

touch veth_script.sh /tftpboot/fw_1/root/

2.  Make the file executable:

chmod +x /tftpboot/fw_1/root/veth_script.sh

3. Add the following contents to the file and save it.:

#!/bin/bash
 
while true; do
        date >> vethcfg.txt
        vethcfg list | head -3 >> vethcfg.txt
        sleep 2
done

4.  Test the script with the following command.  You should see the MLT status scroll as the script continues echoing out the command.

tail -f vethcfg.txt


 

When the script is run you will see similiar results to:

Tue Mar 25 09:05:14 CDT 2014
S Port   Agg  A_KEY  P_KEY  P_SYS_PRI   PARTNER_SYS  MUX    RECV   PERIO   A_STAT   P_STAT
S  1,1     v1  0400  0006      32768  0025b4467600    DIST  CURRNT  SLOW_P L_ASCD__ L_ASCD__
S  2,1     v1  0400  0006      32768  0025b4467600    DIST  CURRNT  SLOW_P L_ASCD__ L_ASCD__
Tue Mar 25 09:05:16 CDT 2014
S Port   Agg  A_KEY  P_KEY  P_SYS_PRI   PARTNER_SYS  MUX    RECV   PERIO   A_STAT   P_STAT
S  1,1     v1  0400  0006      32768  0025b4467600    DIST  CURRNT  SLOW_P L_ASCD__ L_ASCD__
S  2,1     v1  0400  0006      32768  0025b4467600    DIST  CURRNT  SLOW_P L_ASCD__ L_ASCD__
Tue Mar 25 09:05:22 CDT 2014
S Port   Agg  A_KEY  P_KEY  P_SYS_PRI   PARTNER_SYS  MUX    RECV   PERIO   A_STAT   P_STAT
S  1,1     v1  0400  0006      32768  0025b4467600    DIST  CURRNT  SLOW_P L_ASCD__ L_ASCD__
S  2,1     v1  0400  0006      32768  0025b4467600    DIST  CURRNT  SLOW_P L_ASCD__ L_ASCD__

Workaround

n/a