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New Member

Two GRE Tunnels with the same source and destination ip address

HI all,

We have configured a Tunnel GRE and connectivity looks fine, the problem is when we try to setup a second tunnel with a different ip address but the same source and destination ip addresses, then we lost all the connectivity to the box, the IOS image we are running is "c7300-k91p-mz.122-27.SBC2.bin".

Any idea about this issue?

Thanks in advance,

3 REPLIES
Cisco Employee

Re: Two GRE Tunnels with the same source and destination ip addr

If both tunnels have the same source and destination, there is really no way for the router to demultiplex the information coming from one tunnel or the other.

You could try configuring a different tunnel mode on each tunnel (gre on one and ipip on the other) or use different source and destinations addresses (different loopbacks addresses).

What is the reason for the two tunnels between the two same end points?

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México 
Paseo de la Reforma 222 Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
New Member

Re: Two GRE Tunnels with the same source and destination ip addr

Is because we are implementing a MPLS network and we need to manage all the CE routers through a different VPN... we think it is better in this way because setting up tunnels with different ip source address needs a loopback interface per tunnel.

Are we running in the right way?

Cisco Employee

Re: Two GRE Tunnels with the same source and destination ip addr

Enrique,

If you need to have multiple tunnels between the same pair of routers the different loopback addresses is probably your best option.

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México 
Paseo de la Reforma 222 Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
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