Posted on 2014-12-02
We've recently stretched a vlan across a layer 2 link (vlan tagged on a trunk) connecting two different datacenters. I posed a question to a consultant (DR planning) we've been using regarding the SVI for the stretched vlan. The SVI is assigned to a switch in DC1 and all servers in this vlan use the svi as their default gateway. In the event there is an issue with the switch in DC1, the SVI doesn't somehow get assigned to the switch in DC2, correct? Like a sort of failover scenario for the SVI.
The consultant we've been working with claims this will work but I'm not so sure. I don't have a lab environment to test this out in so I'm not sure how I can even come up with a good test for it.
I'm thinking if there is a failure with the switch in DC1, we would have to change the default gateway for any servers in that vlan to the svi in DC2. Unless we use a HSRP or VRRP for failing over that default gateway.
The switches in each datacenter are Cisco 3850s.s