IRB on 1721 router

[bregimand]

I am having a problem setting up IRB between two 1721's on a PPP link. The routers see each other fine, but they cannot see the switches that they are respectively connected to (via ping).

The switches also do not show up in the router's ARP tables.

Here is the config for the Fa0 interface (the same on each router)

interface fa0

no ip address

no ip route-cache

vlan-range dot1q 1 20

bridge-group 1

the rest looks like:

bridge irb

!

int s0

no ip address

bridge-group 1

!

interface BVI1

ip address xx.xx.xx.y 255.255.255.248

no ip route-cache

!

bridge 1 protocol ieee

bridge 1 route ip

I've got VLAN 10 set up on everything as my management VLAN.

Any ideas?

Thanks,

Ben

[Richard Burts]

Ben

Other than wondering why you are doing no ip route-cache on the FA0 and BVI interfaces and why you describe the connection between routers as PPP but do not have encapsulation ppp on the serial interfaces, I do not see problems in the config that you have posted.

I suspect that a clue to the problem is that the switches do not show up in the router ARP tables. Can you tell us how the switches are configured and how they are connected to the router? Is the port of the switch into which the router connects configured as a trunk port?

I might suggest simplifying your environment and after you get the simplified setup working you can add the complexities back in. To start with I would suggest removing the vlan-range from the router interface config and configuring the switch port to which the router connects as a simple access port in vlan 10. Once you get the simple connectivity working and get the IRB working then you can add additional VLANs back into your config.

HTH

Rick

[bregimand]

Rick-

My fault - I typed the config from memory and left off the encap ppp command by accident.

The connection in between the routers and switches is an 802.1q trunk.

I'll give your idea a try.

Thanks,

Ben

[bregimand]

Rick-

I removed the no ip route-cache statements from the Fa and BVI interfaces. I cannot remove trunking from the connection to the switch, as it's not allowed.

I still cannot ping the switch.

Any other thoughts?

[Richard Burts]

Ben

Maybe it would be helpful to have some clarification about what you are attempting to accomplish. Your vlan range would seem to indicate that you want to enable trunking on the router interface. Normally when I see trunking on a router interface it indicates that the router is performing inter-VLAN routing. Your placement of the bridge-group on the interface indicates that you are bridging. Are you trying to bridge all the VLANs together (that would seem to negate the purpose for assigning different VLANs on the switch)? Can you clarify the topology and what you are trying to do?

When I see trunking from a switch to a router interface I usually see subinterfaces on the router for the particular VLANs that you want to process. What happens if you configure a subinterface for VLAN10?

HTH

Rick

[bregimand]

Rick-

I have a client who is doing file/printer sharing across a PPP link, and this is how they originally had the routers setup.

Now I need to have a voice/mgmt VLAN exist across this link, and they don't want me to get rid of the bridging setup. AFAIK, bridging doesn't work with subinterfaces, so I'm at a loss.

Ben

[Richard Burts]

Ben

It looks like you are trying to use the Bridge Control Protocol in your config (the vlan-range is part of that implementation). I have not used that feature before so can not offer any advise based on experience. But I have looked through a bit of documentation about it and have these suggestions:

- the examples that I see for BCP turn off routing (no ip routing). I am not clear whether BCP is supported with IRB. Was the IRB already in place or did you add it?

- one of the things discussed in the documentation was whether you are dealing with tagged frames or with untagged frames. If you are dealing with untagged frames it may help to add the "native" keyword on the vlan-range command. If you are dealing with tagged frames it may help to add "ppp bcp tagged-frame" under the serial interface.

HTH

Rick

[bregimand]

Rick-

I figured out a way to do this. Apparantly this arp issue was by design, as the BVI is the only interface being used, and an arp won't be sent out the same interface it was received in. I think that's what it was, anyway.

So, I got rid of the BCP VLAN range commands, created a sub-interface on the Fa port with a 10.x.x.x address, and created static routes back to my other 2 routers.

Not sure how 'proper' it is, but it works!

Thanks for your help,

B

[Richard Burts]

Ben

I am glad that you figured out a way to get it to work. I think that your solution is quite "proper". Configuration of a subinterface for VLAN10 is a suggestion that I made in one of my responses so I think it is quite proper for your solution.

HTH

Rick

[widsonpf2010]

I would like to know if it is possible to use the Bridge Control Protocol but limit it to a specific interface. Though The pdf guide I downloaded from Cisco shows that I have to disable all routing, I am hoping this could be limited to a given interface while allowing me to use the IP routing features for the other interfaces or ports. My router is a 7602 with an STM1 channelized port adapter. I have multiple group of clients connected with various number of E1s on the router. I need to set the BCP with MLPPP for one particular client. Is it possible to restrict the BCP configuration for only the set of E1 circuits that go to this particular client. Many thanks in advance for any help.