Nexus 5548UP vPC domain with 1x L3 card

[martijnsmit]

Hi,

I can't find anywhere whether it is possible to create a vPC domain with 2 Nexus 5548UP switches, where only 1 Nexus 5548UP has a L3 daughter card.

Does anyone know if this is possible, supported, or both?

The question of "why" isn't important in this case, I know it's a weird configuration. ;-)

[Steve Fuller]

Hi Martijn,

I've never tried this, but I don't see why one of the switches having a Layer-3 module would mean that you can't establish vPC between the two switches. Apart from the peer-keepalive configuration, vPC is really a Layer-2 concept so Layer-3 capabilities shouldn't have any impact.

Also when you look look at the show vpc consistency-parameters command, there are no Layer-3 capabilities considered.

Sorry I can't provide a more definitive answer. I'd be interested to hear how you get on if/when you try it.

Regards

[sean_evershed]

Interesting question.

The only thing that the NX-OS guide for the 5500 switches states is that the vPC peer switches must be of the same type. As stated by Steve vPC is a layer 2 technology so the daughter card is not required.

How do you propose to use the daughter card? Will this be used to provide the Layer 3 gateway for the non-VPC VLANs?

[martijnsmit]

I was mostly just wondering what would happen, as I've found no mention of using the same hardware configuration in the documentation. Also, it would be a good thing to know what would happen if a Nexus 5548UP (with a L3 card) dies that gets replaced with a Nexus 5548UP without a L3 card.

I think I could make a case for a vPC pair where only 1 Nexus switch has a L3 card, where L2 has the priority for high availability, but I would probably always go for the same hardware configuration. 

Thanks for the replies so far, it looks like I at least did not miss it in the documentation where it mentions "same hardware configuration" ;-)