nanog mailing list archives

Re: Are SW upgrades needed in MPLS core networks?


From: Petri Helenius <pete () he iki fi>
Date: Fri, 06 Feb 2004 20:55:00 +0200


Rubens Kuhl Jr. wrote:


I don't get why Juniper and Cisco trie-lookup forwarding would differ in
comparing IPv4 and IPv6; Juniper does a 8+1+1+1+1+... search until a leaf
node is found, while Cisco does 16+8+8 (or something near it but still with
3 phases); for both architetures, IPv6 longer addresses implies walking more
deeply into the tree in order to find where to route.

There is another factor at play here which is memory bandwidth at the lookup engine. If you have to look deeper into the packet than you can accomplish by using single spin trough the thing that fetches x bit wide words from the packet, you´ll effectively half your packet rate.

Doing 8+1+1+1+1+... would seem wasteful for IPv6 with the current address allocation scheme, are you sure that´s what´s used for IPv6 too?

Pete


Current thread: