Back to back BGW connectivity for DCI with VXLAN EVPN Multi-Site.

[SandevChopra07800]

Hi, our customer having 2 x DCs, wants to introduce VxLAN as a layer-2 extension approach rather than traditional way of extending vlans. We proposed to 2 x BGWs (Border gateways) in each DC that will be connected to their existing Core SWs using a double-sided VPC. Design Guide reference: https://www.cisco.com/c/en/us/products/collateral/switches/nexus-9000-series-switches/whitepaper-c11-742114.html

Question I have is are we able to directly connect the BGWs in each site or do we need a site-external network?

If compared to ACI, directly connecting the spines across the sites is supported, you dont need a inter-site-network (ISN). Should work with directly connecting the BGWs also as long as there are two Datacenters only. 

Please advise? 

[Dawei · Accepted solution]

You can connect BGWs on DC1 to BGWs on DC2 without inter-site-network, BGW back-to-back model:

https://www.cisco.com/c/en/us/products/collateral/switches/nexus-9000-series-switches/white-paper-c11-739942.html

[SandevChopra07800]

Thankyou!

[JonathanC1]

I know this is an old thread but curious if you have to use BGWs in a back to back design. Could you theoritically use your spines as the BGW? Similar to ACI Mpod B2B (https://www.cisco.com/c/en/us/td/docs/dcn/aci/apic/kb/cisco-multipod-b2b.html)  Cheers

[SandevChopra07800]

Yes, you can use Spines in a back to back model, but keep in mind that will only be used for 2 sites. Just in case, you get a 3rd site, then it is not supported and you will have to use an ISN network. 

[svenus]

Sorry to bring this up but I could not find relevant information, this thread looks like the most suitable to ride on.

I received a request to build a greenfield 2 sites DCI using BGW back to back model. There is no other spine nor leaf purchased for this project so the 2 BGWs at each site will act as the leaf role. In this scenario, is it supported for BGW/Spine/Leaf all aggregated into one switch?  

With that design, I also would assume vPC will need to run from BGW/Spine/Leaf towards to end hosts (running LACP).  Is that a valid design?  

Customer requires these configurations to be managed by NDFC, so what role should I set for the BGP/Spine/Leaf?

Thanks.

[JonathanC1]

I'm pretty certain this would work and you could do it through NDFC but lots of caveats to keep in mind like suboptimal routing. I would personally lab it on vCenter with Nexus dashboard & N9Kvs if it was for a customer before getting too far in.