L2 Trunk or VXLAN for Overlay Network

[Rene Mueller]

Hello,

I have a Design Question and hopefully someone can help me out. 

We have 3 Serverrooms on our Campus and we want to have an Overlay IP Subnet in our main serverrooms (1 and 3). There are Nexus Switches running and there is the possibility to connect the Switches directly together via a fiber link. Also there are core switches in between which to dynamic EIGRP Routing. 

In my perspective, I have two options now:

1. Use the fiber links to connect the Nexus Switches together and setup a L2 Trunk in between. Then use HSRP on the VLAN Interfaces for active/standby Default Gateway for the Servers in the Overlay IP Subnet. 

2. Don't use the fiber links, but use the existing routing on the campus and setup VXLAN with Anycast Gateways on the Nexus Switches.

I am new with VXLAN and I don't know in detail how Anycast Gateway works. Will both VTEP have it's Default Gateway active for servers or is it similar to HSRP and only one VTEP has an active Gateway and Traffic will be send from the passive VTEP to the active one for Gateway Traffic? What will happen if routing fails? Will then both VTEP be active with it's Gateway IP? 

[lovsharm]

hsrp anycast will work in synch as any vtep can work as GW and there will be no change in the GW mac and ip on any vtep for the same vlan, but you need to configure mac and ip manually on all vtep. 

[Rene Mueller]

So what is the benefit when using VXLAN instead of L2 Trunks between serverrooms? I think VXLAN makes sense when you have no fiber connection in between. But in my case, I have the option for direct fiber links. But I don't know if VXLAN makes sense because I don't know this protocol in detail

[lovsharm]

It is L2 extension over L3 like OTV with more flexibility. if you have L2 connection already, Vxlan is not needed.

 have a look at this https://www.ciscolive.com/c/dam/r/ciscolive/emea/docs/2016/pdf/BRKDCT-3378.pdf