Issue with PCs moving on LACP link

Tom404

Hello,

So I just opened a case with Meraki but thought I would post here as well. Here is what I sent in for the case :

I recently started having an issue on our HQ network.

We have one stack for L3 routing and L3 out and 2 stack for distribution. The distribution switches are connected to the core throught one aggregat LACP of 2 links one for each node.

Every morning, when people connect to the network and packets start flowing through the network, I have to close the two links to the MS410-01. otherwise some users have no network

It's pretty difficult to troubleshoot and do some tests since when there is nobody connected to the network everything look fine.

If you have any idea 🙂

alemabrahao

Are you sure that LACP was configured property?

alemabrahao

Have you checked the STP configuration?

Brash

Definitely sounds like your port channel either isn't configured properly, or isn't applying properly.

Tom404

LACP is properly configured (speed/duplex/vlan match...) root guest is enable on the core switches... This problem appears after a migration of a L3 interco, I just changed the default route then rollback.

I'm used to Cisco catalyst and never faced this kind of issue...

Really strange

alemabrahao

I have never worked with Interco, maybe It's an Interco issue.

JacekJ

Just a side note, this bug can be very nasty (has been fixed on MS 15.20):

"Stack routing tables can be incorrect after removing an SVI (present since MS 14.32)"

Tom404

Very interesting... I'm in 14.33. I'll do the upgrade and tell if it resolves this issue.

Thanks !

JacekJ

You can reboot the MS410 stack to see if this is causing you issues (done that quite a few times when that wasn't reported as a known issue). After a reboot everything should run ok, as you set it up in the dashboard.

So the current work around if you need to remove a SVI - is either not remove it at all, or remove and then do a reboot of the stack AFAIK.

The MS15.21 is the first 15.xx that got into stable, so I would wait a bit with the upgrade just to be on the safe side.

cmr

We had the issue with an MS355 stack running 15.18/19 and rebooting it didn't help... The upgrade to 15.20 did fix it.