route-cache query

From: Holmes (iamholmes@eml.cc)
Date: Tue Nov 08 2005 - 12:55:07 GMT-3


Hi all -

        I'm looking at a load-balancing case, where IP per-packet
load balancing is being done. (I'm using cef, and ip load-sharing
per-packet).

Briefly, if we were doing load balancing over 2 T1 links, router
to router, say a router has 2 serial interfaces, if route-cache were
enabled, it doesnt always have to do a look up, but would
have an entry that for any traffic with this source / destination
pair and send all further traffic over this interface (basically
per-session or per destination load balancing).

With cef, there no such source/destination pair stored, its a
little more CPU intensive, but we can get IP packet level
load-balancing.

Now to my question :

Why is `ip route-cache / no ip route-cache configured at the interface
level, and not at the global level ? Isnt the decision to send a
packet out to a certain destination over a certain interface made
before-hand ie. If you configure no ip route-cache at the interface
level,
isnt it too late, the path / interface has already been chosen.

Thanks for any replies.

-- 
  Holmes
  iamholmes@eml.cc

-- http://www.fastmail.fm - Or how I learned to stop worrying and love email again



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