IRB question

Unanswered Question

I have a problem I hope can be figured out here. I need to transport proprietary Ethernet frames across an IP network while still routing IP packets on the same interfaces. It looks like IRB will do the trick but I am unclear as to how to get the bridged frames across the network to the other router.

Here's the scenario - There are two workstations used to control satellite bandwidth. They are geographically diverse but connected via private IP network. The two workstations use a proprietary Ethernet frame for some of the inter-communication between them while the same interface is used for managing the workstations via IP.

I've configured IRB on both routers with the “bridge irb” command, configured the bridge group on the interface facing the workstations and created BVI interfaces for the bridge groups. I set the bridge protocol to IEEE and configured the bridge group to “route ip”. So far everything works fine, the workstations can see each other through IP, but I don't see the proprietary frames. How is it that the bridged frames get across the IP network?

I have included some documentation to help make this clear.

Thanks in advance

I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Richard Burts Mon, 01/26/2009 - 10:17


Would I be correct in assuming that the special Ethernet frames have an Ether type code of something other than IP? That would mean that the non-IP (special) frames are being bridged. So what you really need is some method of transporting the bridged frames over the IP network?

I would suggest that DLSw+ was designed to take non-routed/bridged traffic and encapsulate it in IP to transport over IP networks, and decapsulate it at the destination and bridge it on to its destination. And if you use DLSw+ then I believe that you do not need IRB on those routers.



Giuseppe Larosa Mon, 01/26/2009 - 10:21

Hello Dean,

you have two choices

or you create a L2 path in the network using bridge-group on all involved interfaces (both directions) end to end on all routers (this is the meaning of the bridge-group command)

or you use a more modern and efficient way to carry L2 traffic over an IP network like

L2TPv3 and may be with a double link on the local network (one for IP and one to handle L2 frames)


Hope to help


Giuseppe Larosa Mon, 01/26/2009 - 11:44

Hello Dean,

if you have a L2 switch you could use subinterfaces (if you can separate in different vlans the two types of traffic) because L2TPv3 works well on subinterfaces.

if this is not feasible the DLSW solution suggested by Rick is a better choice.

Hope to help



This Discussion