Hi all. I've been getting the following message
%IP_VFR-4-FRAG_TABLE_OVERFLOW: GigabitEthernet0/2: the fragment table has reached its maximum threshold 64
Its now at 64 but has been at 16 and 32 and it grows as our clients grow. I do know why this happens but my question is:
Packets stay at an interface fragment table on input before being processed? My logic says yes but I would like to hear some confirmation and what you have to say.
Attached is a quick drawing of our edge network. Gi0/3 is a subnet of http caches where packets are forwarded by WCCP on a GRE tunnel. packets FROM the caches are not GRE encapsulated.
I hope my question is clear
Thanks to all
They are held waiting for the subsequent fragments in an effort to reassemble all of them to get a complete view of the packet.
See:
http://www.cisco.com/en/US/docs/ios/12_3t/12_3t8/feature/guide/gt_vfrag.html
It's best to try and prevent fragmentation if at all possible. For example, if you know it's TCP and there will be some overhead due to a GRE header you could have the device adjust the TCP MSS size to account for it:
http://www.cisco.com/en/US/tech/tk827/tk369/technologies_white_paper09186a00800d6979.shtml