GRE Tunnels - Packet Sequencing

[kondic]

Hi All,

I've been unable to find this tidbit of information anywhere, but my question is, in a GRE tunnel which traverses a multipath cloud, will the packets at the destination come out of the tunnel at the same order they came in, or can their sequence be changed during the transit of the tunnel?

I've read about a new 'sequence' option for GRE tunnels in the RFC which may address this, but cannot se anyway to implement this in IOS if this is indeed the solution.

Any thoughts?

Thank you!

[pkhatri · Accepted solution]

Hi,

If you enter the 'tunnel sequence-datagrams' under your tunnel interface configuration, that will enable the sequence number option as per RFC2890.

The output of 'sh interface tunnel' will show the sequence numbers for received and transmitted packets after that..

Note that this will also configure the tunnel interface to drop datagrams that arrive out of order

Hope that helps - pls rate the post if it does.

Regards,

Paresh

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[kondic]

Thanks for the info, it will help me in my quest to diagnose a cranky videoconference system complaining of out of sequence packets across our DS3!