loop in 5600 connectivity

[MKH]

Hello

We have two NX5600 7.1.4 in our network. We run VPC between them and enable peer-switch. We have stacked two 3850 and connected them  to N5600s with 4 link (full mesh). We have used 1 port-channel for connectivity of 5ks and  3850.

Should we enable spanning-tree on 3850 switches?

Do we need to  enable spanning tree if we don't enable peer-switch?

Thank you.

[chrihussey]

So you have a 3850 pair in a stack, each switch in the stack has a link to each of the 5600s for a total of four links and the 5600s are operating in vPC mode.

1- Spanning tree should be enabled by default on the 3850s.

2- I wouldn't configure vPC without enabling peer switch.

I believe it is best practice to make the N5600s the spanning tree roots by giving them the same priority for all VLANs.

Even though the resulting logical topology may not have a spanning tree loop, I would not recommend removing it. It's not going to hurt anything and in the end may even prevent problems.

Hope this helps.

[MKH]

I appreciate you so much.

Do I need to  enable spanning tree on them If a have 3rd party switch instead of 3850 switches?

Thank you.

[chrihussey]

If you are asking if you need to enable spanning tree on the 3rd party switches my answer would be probably so. But you would need to make sure there were no compatibility issues and that the 3rd party switches see the N5Ks as root. The protocol is a standard, but when you start mixing different vendors there is always the possibility of problems.

The results may even vary between different vendors and you just would need to test it out and verify it will work is all I'm saying.

Regards

[Rick1776]

Just make sure when you connect to a 3rd party switch or a non Nexus switch you enter the command spanning-tree port type normal if you use network it will run bridge insurance and will shut down vlan's it doesn't receive bridge insurance packets. You could run edge if you would like but I would just port type normal.

[Rick1776]

Here's a good link with the explanations.

https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5000/sw/configuration/guide/cli/CLIConfigurationGuide/SpanningEnhanced.html