DHCP & Multiple rack controllers

We’re having a few issues and I want to make sure that it’s not me mis-understanding what should be. version is 2.6.0 beta 2.

  • We have 2 region controllers in 2 different racks, call them (regiond001 regiond002)
  • We have 2 rack controllers in 2 different racks and different DNS domains (rackd001.cluster1 rackd002.cluster2)

Everything has a single interface, and no VLANs are in use so it’s all untagged.

The rack controllers control a single, unrelated rack, call it cluster3.example.com.

I created a fabric called cluster3-rack1, vlan untagged, subnet as

The switch in rack1 has DHCP helpers pointed to both rack controllers.

  • It doesn’t seem possible to assign HA DHCP servers on 2 different subnets with DHCP relay.
  • On the VLAN page, the “rack controllers” section is empty and I can’t add a rack controller.
  • The generated DHCP for the subnet is missing the next-server and doesn’t get sent to the client (confirmed with tcpdump)

So, on relay dhcp subnets, one rack controller is a single point of failure. I’m not sure, since the terminology of relaying DHCP requests from a VLAN to a VLAN doesn’t really make sense. I’ve only known DHCP helpers to point to a single IP, so it should be a rack controller (or set of rack controllers), not a VLAN.

Hey Andrew

Your project sounds like fun! Have you checked out the HA configuration docs?

Also have you checked out the advanced cli tasks regarding registering your rack controllers with the region controllers