VSS - vPC L3 MEC connectivity

[sal-mahmood1]

Is  VSS - vPC-switches  connectivity with single L3-MEC supported? Or I have to do  2 MECs to VSS from vPVC-switches (one from each vPC switch)?

[Reza Sharifi]

Yes, you need 2.  That is one /30 for each VPC switch.

HTH

[sal-mahmood1]

Thanks for the answer.

This means I will need to have 4 wan links for two MECs between VSS and vPC (my VSS and vPCs are few miles apart).

[Reza Sharifi]

Correct.  You need 4 links between the VSS and the 2 VPC switches (Nexus). You would need to create 2 layer-3 Portchannels (say 2 and 3) Po2 will be on one VPC switch and Po3 on the other one. Each Portchannel has 2 physical links which connect to both VSS switches.

HTH

[sal-mahmood1]

Do you know what is the reason for this restriction on the single-mec between vPC and VSS? vPC-to-vPC, vss-to-vss do not have this restriction. My understanding was that VSS-mec and vPC do not care about what is on the other side of the port-channel.

[Reza Sharifi]

Two different technologies. VSS act as one device with one brain controlling both chassis.  With VPC, they are 2 different boxes and 2 brains. That is why with VPC you still need to run VRRP, HSRP, if they are the end devices gateways, but that is not needed for VSS.

HTH

[sal-mahmood1]

I really appreciate you quick reply. Than you.

Does it mean if configure single mec between vss-to-vPC and put the mec in an SVI and then run HSRP on the vPC side it will work?

[Reza Sharifi]

I am not sure, as I have never deployed it that way.  You could certainly try it in the lab and if it works test the fail over.