I have hub and spoke arch. The two of the spokes are using BVI10 on the same subnet. The Hub has two serial interfaces, one facing Spoke1 (BVI10) and the other facing Spoke2 (BVI10). These two Spokes can share broadcast (ie DHCP). The Hub also has a uplink ethernet port with a BVI50 that is peered with a Core Router BVI50. The broadcast of the Spokes (BVI10) does not mix with (BVI50) which is great UNTIL we want it to. We want to go into a mode where all the DHCP request from the spokes get sent to the CORE.

So essentially, I want upon 'manual' intervention of a configuration change (yes they want manual) that the two bridge BVIs share DHCP request up to the CORE but I cant get them to cross.

Ive experimented with IP Helper-addresses, Bridge 50 domain 1 with Bridge 10 domain 1 on the Hub router, IP DHCP Smart-relay, placing secondary IP addresses on BVI10 that are in the same subnet as BVI50.

Any ideas on how to cross them from one interface to another bridged interface? I would have thought that the Bridge IRB and BVI would have allowed routing between them. Im holding my breath that I dont have to pull out a router on a stick. I must be missing something simple.

For now, We are stuck with bridging due to some unmentioned items in the architecture.