[c-nsp] VPC + MLAG but more of a general question I guess

[Drew Weaver]

Hello,

If you have two Cisco switches in a VPC domain and then you connect another pair of switches downstream (that also run MLAG/VPC) is it required that all of the port-channels [for the partner network, not the peer-link] between those two sets of switches use the same VPC id?

Example:

VPC ID 18
C9336-1 -> Downstream-Switch1
C9336-2 -> Downstream-Switch1

VPC ID 19
C9336-1 -> Downstream-Switch2
C9336-2 -> Downstream-Switch2

Typically if a port channel configuration is invalid on the C9336 side it will put one of the ports into Stby to prevent loops but in this case the Cisco end doesn't see any problem with anything whatsoever.

The other vendor really seems to be having a hard time though:

<188> Jul  8 12:56:37 LAB1-1 DOT3AD[dot3ad_core_lac]: dot3ad_lacp.c(2332) 6475060 %% WARN Interface [ifName not found(803)] partner key 32786 is not same as existing members of LAG interface Po2 (32787). Not adding interface [ifName not found(803)] as active member of LAG interface Po2.

There are a couple of things here that I guess I have to ignore because the other vendor won't look into it even though I've pleaded with them to do so.


  1.  [ifName not found(803)] in the WARN message [????]
  2.  The switch actually DID add the interfaces to PO2 even if it continually says that it can't do that.
     *   Po2       Active: Te1/0/1, Te1/0/2      Dynamic  7         1         Disabled  0         0
  3.  The most important thing is that this configuration actually *functions* even when testing failure domains.

Should connecting a pair of MLAG switches downstream from a VPC domain be any different than connecting any other host to a VPC domain?

My thinking is that the uplinks from each downstream switch really don't have anything to do with each other, which is why I configured them in separate VPCs on the Cisco side.

The second vendor is telling me that po2 from each downstream switch has to be in the same VPC on the Cisco side which isn't really clicking/making sense to me.

Anyway this turned out way longer than I wanted it to be, thanks in advance if you even read it.

-Drew