01-21-2014 07:43 PM - edited 03-01-2019 07:30 AM
The system mac and root bridge mac addresses are same on both the primary and secondary vPC. How those are elected and related.
Commands:
sh vpc role
sh spanning-tree
Thanks,
Manu
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01-22-2014 12:29 PM
VPC Primary switch MAC-address. I think this is assigned by the switch resoruces internally.
Cheers,
01-23-2014 11:47 PM
Hi Manu,
As Amit says, the MAC addresses are assigned from an internal resource on the switch. On the Nexus 7000 the show sprom backplane command will give you the starting MAC and the number available.
Regards
01-22-2014 12:38 AM
Hi Manu,
That is the VPC magic :-). That being said,when you have device configured as the VPC-peer, they use a common system MAC or the Primary VPC switch to be forwarded to the downlink devices for the STP. This way we modify the STP behaviour and the VPC domain represent itself as a single root bridge to STP which runs in the background. The downlink devices see the BPDU's coming from a single device as this is all controlled by the VPC Primary switch. VPC Primary switch syncronizes the STP state with peer switch using CFSoE. Once both the peers are synced, all the VPC ports are controlled by the VPC orimary switch.
Hope this helps.
Cheers,
-amit singh
01-22-2014 07:42 AM
Thank you Amit.
I have a vPC between two N7K. I did show spanning-tree and show vpc role on both the device. The vpc-system mac (sh vpc role) and root-id and bridge-id (sh spanning-tree), all the 6 mac addresses are same. vPC local system-mac is different. So my question is, what mac address is electing as the Nexus root id mac address.
I hope i am not confusing you..:-)
Thanks,
Manu
01-22-2014 12:29 PM
VPC Primary switch MAC-address. I think this is assigned by the switch resoruces internally.
Cheers,
01-22-2014 06:39 PM
Hi Amit, appreciate your help. Sorry to disturb you again. In legacy switches show version command will display the switch mac address. What command can use in Nexus?
01-23-2014 11:47 PM
Hi Manu,
As Amit says, the MAC addresses are assigned from an internal resource on the switch. On the Nexus 7000 the show sprom backplane command will give you the starting MAC and the number available.
Regards
01-24-2014 12:32 AM
Okay, i will check. Thank you Steve & Amit.
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