VXLAN Design Question

[paul1202]

Hi,

Customer has an EVPN BGP VXLAN Spine and Leaf deployment at a single DC managed by DCNM.

There is now a requirement to add a single pt-pt L3 backup circuit to the Fabric from another site.

Both Spines are configured as BGW's and successfully have external connectivity to the Campus network and the wider world.

Can we connect the single backup circuit to only one of the Spine switches and have an iBGP peering between the 2 Spines (BGWs) or maybe have to connect the circuit to a L3 switch which will have L3 peering to each BGW Spine.

Alternatively, we could terminate the backup circuit to the DC's Campus network and route traffic down as the per the current external connectivity, but they really want the backup traffic to be avoid the current routed path.

Thanks.

[drumfrodo]

This would be regular Border Spine connectivity, and not really related to BGW function (which is a distinct EVPN multi-site role). Seemingly you already have external connectivity on the same nodes, so adding another external L3 connection should be smooth sailing. There should be no need for additional iBGP peering within the fabric for this connectivity, as the reachability across it will be distributed via the internal BGP EVPN peerings anyway. However for redundancy it would be beneficial to connect the circuit via your mentioned L3 switch/router which can then peer to both spines so future maintenance/upgrades on them is possible without taking down the external backup connectivity.

[paul1202]

Thank you for your reply.

As it's only a backup circuit to the existing production circuits, only one is required.

As you've confirmed the route(s) will be advertised over the BGP EVPN peerings we should fine.

I think I got confused when deploying a Multi-site solution where we needed to stretch VLANS between fabrics and the circuits terminate directly on the Spines.

I had heard from a Cisco SE that it is now possible to directly-connect the Spines together to ensure traffic is not black-holed in the event of a Spine or circuit failing.

Thanks again.

[apay4mb]

Hi,
Can I ask for the design you mentioned:

'Both Spines are configured as BGW's and successfully have external connectivity to the Campus network and the wider world.'

Will be good if you provide any information, link or related documents.

Thanks