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Beginner

7206 VXR Issue with GRE Tunnels

Hi,

Has anyone come across issues with multiple GRE tunnels between two devices when using the same source and destination addresses. I've tried using tunnel keys but this makes no difference. The only way I can get this to work is between different source & destination addresses.

Thanks,

Adam

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VIP Mentor

7206 VXR Issue with GRE Tunnels

Hi,

I do not believe that it works to have 2 GRE tunnels with exactly the same source and destination addresses between 2 routers. I believe that there must be at least one unique address (source or destination) for each tunnel.

http://www.cisco.com/en/US/docs/ios/interface/command/reference/ir_t2.html#wp1012689

Usage Guidelines

#

The source address is either an explicitly defined IP address or the IP address assigned to the specified interface.

#

You cannot have two tunnels using the same encapsulation mode with exactly the same source and destination address. The workaround is to create a loopback interface and source packets off of the loopback interface.

#

When using tunnels to Cayman boxes, you must set the tunnel source command to an explicit IP address on the same subnet as the Cayman box, not the tunnel itself.

#

GRE tunnel encapsulation and deencapsulation for multicast packets are handled by the hardware in PFC3 and 12.2(18)SXF and later releases. Each hardware-assisted tunnel must have a unique source. Hardware-assisted tunnels cannot share a source even if the destinations are different. You should use secondary addresses on loopback interfaces or create multiple loopback interfaces to ensure the hardware-assisted tunnels do not share a source.

Regards

Please rate if it ehlps.

Beginner

Re: 7206 VXR Issue with GRE Tunnels

Thanks for the reply, but I know that this can be done using tunnel keys. I tested this today on different platforms and it worked fine, it just seems to be an issue when one of the tunnels is on the 7206.

Sent from Cisco Technical Support iPad App

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Frequent Contributor

7206 VXR Issue with GRE Tunnels

i will call it a bad design

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Posted by WebUser Ahmed Saud from Cisco Support Community App

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Beginner

Re: 7206 VXR Issue with GRE Tunnels

Thanks for the utterly unhelpful reply. I haven't asked about the design, I've asked about the functionality.

Sent from Cisco Technical Support iPad App

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