08-23-2022 08:28 PM
Hi everyone ... hope everyone is doing well !!!
I have spanning-tree related questions and looking for inputs/suggestions .. thanks all in advance !!
I am attaching a new pair of Nexus 93180s to a stack of Cisco 3650s via vPC. The Cisco 3650 stack is currently the spanning-tree root on my network and I would like the Cisco 3650 stack to continue be the spanning-tree root when it's connected to the Nexus 93180s. My concern is the Nexus 93180s may become spanning-tree root and cause traffic disruption due spanning-tree convergence. My end goal is to prevent the Nexus 93180 to become spanning-tree root.
Questions,
1. Do I simply change spanning-tree priority on the Nexus 93180s to be higher than the 3650 stack ?
2. Anything in the vPC config on the Nexus 93180s that I need worry about ?
I will eventually promote the Nexus 93180s to be spanning-tree root when I am ready to retire the 3650 stack.
Thanks you all for your help !!!
Danny
08-23-2022 11:11 PM
>...Do I simply change spanning-tree priority on the Nexus 93180s to be higher than the 3650 stack ?
Yes, no further worries 'needed'
M.
08-24-2022 12:55 AM
when you configure vPC - you use spanning-tree port type network for STP bridge assurance.
downlink towards edge switch config also make sure you use vPC on port-channel.
vPC best practice for reference :
08-24-2022 02:30 AM
Hard so Hard to answer this Q.
08-24-2022 07:19 AM
Thank you very much for your inputs gents !!! very much appreciate your help !!!
Danny
08-24-2022 07:30 AM
I didnot meaning anything
BUT
it really hard
let explain the issue
there are two VLAN
vPC-VLAN and non vPC-VLAN
for vPC-VLAN the Root config in one vPC Peer and secondary Root config also in Secondary vPC Peer
the issue come from
the NSK Peer always make STP of vPC-Link as FWD status
that no problem if root is one of vPC peer
but config other SW as Root and as I mention above the vPC-Link is FWD
this unpredictable and need more analysis how the vPC deal with this case.
that why I say Hard to answer.
if I get something I will update you
08-24-2022 07:43 AM
Thanks MHM !!! appreciate your help as always !!!
I had a similar scenario a few years ago. I connected a pair of Nexus 7010s to a 6509 via vPC and I am pretty sure I had the Nexus 7010 as root and I don't remember experiencing any issues. That was when I migrate from the 6509 to a pair of Nexus 7010s.
I am being cautious this time .. just making sure I am not disrupting the business when connecting the new Nexus 9k to a production Cisco 3650 stack.
Thanks !!!
Danny
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