LACP interface flapping

Products

• XOS

Issue/Introduction

Multi-link LACP group interface flapping on a VAP group running any routing protocolA VAP group configured for multi-link LACP group interface and running dynamic routing protocol may experience system instability.

The following messages are repeatedly  seen in the /var/log/messages file.
<snip>
Jul  8 18:08:31 test_1 kernel: veth: port 2,1 stop distributing.
Jul  8 18:08:31 test_1 kernel: veth: port 2,2 stop distributing.
Jul  8 18:08:31 test_1 kernel: veth: port 2,3 stop distributing.
Jul  8 18:08:31test_1 cbsvapcfgd[31880]: [I] Removed alias inside:1 for cct 1021 - 192.168.1.1
Jul  8 18:08:31 test_1 cbsvapcfgd[31880]: [I] Removed alias outside:1 for cct 1071 - 172.16.1.1

Jul  8 18:08:35 test_1 cbsinitd[2541]: [I] daemon 'daemon.cbshagentd' (prcnam:cbshagentd) is running with 2 pid(s)
Jul  8 18:08:36 test_1 cbsinitd[2541]: [I] starting daemon 'daemon.ospfd' using command '/etc/rc.d/init.d/ospfd start'
Jul  8 18:08:36 test_1 cbsinitd[2541]: [I] starting daemon 'daemon.nsm' using command '/etc/rc.d/init.d/nsm start

Jul  8 18:08:36 test_1 kernel: veth: port 2,4 start distributing.
Jul  8 18:08:37 test_1 kernel: veth: port 2,3 start distributing.
Jul  8 18:08:37 test_1 kernel: veth: port 2,2 start distributing.

Cause

The LACP  flaps  if the routing protocol logs are 2GB in size and, when the routing protocol daemon  is started, it is unable to write to this log.

Resolution

Workaround

Delete the logfile  and restart the routing protocol.

For example
To delete the ospfd.log from the test VAP group:

From the CPM:

rsh test_1
cd /crossbeam/logs
rm ospfd.log


To prevent the routing protocol logs growing to 2GB in size over time, rotate the log files daily.
Refer to articles 000006066 and 000006067   How-to-rotate-default-routing-protocol-logs?