GRE Tunnel

Unanswered Question
Feb 2nd, 2009

I need to know if GRE tunnel is processed in Software of hardware on following routers/switch models ?

6500 running sup720 running native IOS





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Roberto Salazar Mon, 02/02/2009 - 16:03

For 6500 with Sup720:

HW support

Currently, Cat6k Sup720 supports GRE & IPIP mode of tunneling in HW. Tunnel tos & Tunnel ttl options are also supported in HW.

SW support

Certain tunnel features, such as tunnel checksum, tunnel path-mtu-discovery,

tunnel sequence-datagrams, tunnel flow egress-records, tunnel key when applied

on the interface, are supported in software. For features requiring software

processing, we create a 'punt' adjacency in HW, to punt the packet to the software

path. Tunnel mode nos is supported in software. Also, IPX & Appletalk & Multicast & NAT tunneling are supported in software. Packets requiring fragmentation (where input interface mtu > tunnel ip mtu) are sent to software for fragmentation.


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