topic RE: Port flap on LACP load sharing group causes permanent network loop in ExtremeSwitching (EXOS/Switch Engine)

Port flap on LACP load sharing group causes permanent network loop

Tim_DeNike — Wed, 04 Jun 2014 17:04:00 GMT

Had a neat issue that killed our network the other day. Tracked it down to a flaky port on a single switch that was connected to a stack with LACP. I was able to reproduce the problem.

Take a stack and LACP load share one port from each stack member to 2 ports on another switch, send some multicast traffic across it (VRRP or ELRP is enough), then unplug and plug in one of the ports several times.

Eventually, the LACP link will stop forwarding within the confines of the algorith and it turns the ports into a big L2 loop. Doesnt seem to happen with static sharing, just LACP. Reproduced on x450e-48p, but appears to happen on x460s as well, 15.3.3.5p1-2

RE: Port flap on LACP load sharing group causes permanent network loop

Sumit_Tokle — Thu, 05 Jun 2014 00:04:00 GMT

Please call the TAC and report the bug.

RE: Port flap on LACP load sharing group causes permanent network loop

Tim_DeNike — Thu, 05 Jun 2014 01:27:00 GMT

Case open for 3 weeks.

RE: Port flap on LACP load sharing group causes permanent network loop

Sumit_Tokle — Thu, 05 Jun 2014 10:35:00 GMT

Can I have case number?