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Bridge tunnel with EIGRP

I am trying to implement a bridged tunnel for multi-vlan traffic as well as EIGRP routing. I am using two cisco 1811 routers. When I get the tunnel up the EIGRP neighbor keeps flapping up / down. Any ideas as to why this occurs ? Has anyone configured something similar ?

6 REPLIES

Re: Bridge tunnel with EIGRP

Not quite sure what you mean with a "bridged tunnel".

Could you please show some config or clarify in some more detail what & how traffic is to be transported?

One remark about tunneling:

Your tunnel must be a GRE tunnel as a standard IPsec tunnel will not forward the EIGRP multicast hello's.

Regards,

Leo

New Member

Re: Bridge tunnel with EIGRP

I have attached a text file of the config for one side of the tunnel, the other side is configured the same.

Re: Bridge tunnel with EIGRP

I looked at your config and noticed that you only enable EIGRP for the tunnel itself. I would rather use network 10.0.0.0 with a distribute-list.

The other possible issue may be that your tunnel is clogged with broadcast traffic. What is the actual bandwidth on the tunnel?

Regards,

Leo

Silver

Re: Bridge tunnel with EIGRP

I dont think bridging feature on GRE is supported, may work though. I suggest removing IP from the main interface and configuring it on a BVI interface and see if it solves the flapping problem. Do you see the neighborship going to 'SIA'

New Member

Re: Bridge tunnel with EIGRP

I also don't believe that GRE tunnels support bridging. The GRE encapsulates the packet with a L3 header with the protocol type (0x0800 for IP) and a source/destination IP pair. Since all of this is L3 based, I don't think a L2 tunnel would work.

Gold

Re: Bridge tunnel with EIGRP

I suspect the above comments about bridging a gre may be true also but the most likely reason the EIGRP is flapping is becuase you are learning the tunnel endpoints inside the tunnel. The bridging just confused things.

Assume your tunnel is up and EIGRP Is talking between 192.168.1.1 and 192.168.1.2 The local router that you have posted the config for is also advertising that you can get to the 10.103.128.8 network via the tunnel.

The problem is 10.103.128.12 in is that network. The router whose configuration you did not post must have this address as the tunnel destination. You now have the classic problem of the tunnel end point being reachable via the tunnel. You will need to have a staitc route or something to override the EIGRP route that is learned via the tunnel or it will flap.

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