MS150 stack random uplink drop

[u/rootj0]

Hey folks,

I'm looking for some insight on an issue we're troubleshooting.

We have a stack of five MS150 switches connected to an MS225 core switch. On a random day at around 3:03 PM, the entire stack went down and lost communication with the core.

The odd part is that the core switch reported a Layer 1 UDLD error, indicating the fiber could transmit but not receive data. We checked the fiber and SFPs, and everything appeared to be fine. We're using Cisco SFP+ modules.

On July 18, we upgraded the stack to MS18.1.8. The incident occurred on the 29 july, we collected the console logs and sent them to support. So far, the only explanation we've received is that there may have been a synchronization issue within the switch stack.

We also performed a remote reboot of the stack, which reproduced the same issue. We collected another set of logs and provided those as well. Support has since suggested waiting for a newer firmware release, but we haven't received a definitive root cause.

Has anyone experienced something similar with an MS150 stack or MS225 core? Any recommendations on what else to check?

For reference:

No switching loops detected.

We do see some MAC flapping, but it's related to APs and wireless client roaming, and nothing that should bring down an entire switch stack.

Fiber and transceivers appear healthy on inspection.

I'd appreciate any suggestions or ideas on what to investigate next.

[u/topher358]

For what it’s worth I have standalone MS150s and MS225s and neither have any issues. I actually try to avoid stacks because I find they tend to have more problems then benefit over the long haul

[u/rootj0 → u/topher358]

While I appreciate your feedback your comment does not help I don't know your environment how much you test scenarios but to say stacks are more problematic does not help here.

[u/cptluu → u/rootj0]

I am responding to your request you left on my post.
Unfortunately I did not see some of the errors you have stated.

I spoke to one of my Cisco reps on my account and it was advised to just avoid 18 unless you have a reason for it.

My only reason for some networks is they have stacked switches and there was a known bug with APs in stacked switches where roaming broke. That was fixed in 18.

[u/SFTech415]

Are you using the Cisco stacking cables (SC) or a patch cord (PC) to uplink the switches?
We just had an issue with new SCs last week where they're passing Vlan 1 but no other Vlans. 2nd project in 2 weeks.

If you're using SCs, I would power down the stack, remove the SCs, install and program PCs between the switches.

From 3 years ago:
Cisco stacking cable cause stack to crash…

“I have called Cisco Meraki support to ask them what happened, and they told me it is a known issue with "Cisco" branded stacking cables. “

https://www.reddit.com/r/meraki/comments/14g3o6h/cisco_meraki_stacking_wtf/

[u/rootj0 → u/SFTech415]

Interesting! we are using Meraki stacking cables. From our back and forth they assume the MS18 firmware might be causing issues not complete information, now it could make sense since the sync between the switches was failing but nobody mentioned the cisco stacking cables could be causing this issue