From: Scott Morris (swm@emanon.com)
Date: Wed Jul 16 2003 - 12:10:36 GMT-3
It really isn't a speed issue rather than an aggregation one. Whether
you route first or redirect first will be a negligible processing
difference on any router.
From the aggregation standpoint, the answer is different. If you have
multiple ethernet LANs going to a single T-1 to the Internet, you either
have multiple "in" redirects on the ethernet, potentially with exception
lists for internal sites, or you have a single "out" redirect on the T-1
interface which captures everything headed towards the internet
anyway...
It becomes a design question rather than a processing question. (While
technically you are correct, the amount of difference it would really
make doesn't make it worthwhile)
Scott
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Brian McGahan
Sent: Wednesday, July 16, 2003 10:53 AM
To: 'Jim Phillipo'; ccielab@groupstudy.com
Subject: RE: WCCP Question
Jim,
The redirection direction doesn't have anything to do with where
the cache engine sits. It has to do with when the redirection is done.
Redirecting 'in' is faster that redirecting 'out', since the
redirection is done before the routing table lookup and switching is
done by the router. If you redirect the packet while it's going 'out',
then the router just wasted the time doing a lookup and switching a
packet that has to be possibly redirected to another interface.
The router learns where the cache engine sits by running WCCP.
Either the cache engine has the router's address configured by its
unicast address, or it announces to a multicast address that the router
listens for.
HTH,
Brian McGahan, CCIE #8593
Director of Design and Implementation
brian@cyscoexpert.com
CyscoExpert Corporation
Internetwork Consulting & Training
Toll Free: 866.CyscoXP
Fax: 847.674.2625
-----Original Message-----
From: Jim Phillipo [mailto:jim.phillipo@guardent.com]
Sent: Wednesday, July 16, 2003 5:35 AM
To: ccielab@groupstudy.com
Cc: 'brian@cyscoexpert.com'
Subject: WCCP Question
With WCCP we have the option of :
ip wccp web-cache redirect in
or
ip wccp web-cache redirect out
My question is, does the cache engine need to be on the same segment of
the interface with the out keyword ? or does the router redirect those
outgoing packets to another interface where the servers are ?
I can't see a reason to use the out keyword ? Why not put the in keyword
on all the routers with hosts on them ?
Any thoughts ?
Jim Phillipo, CCNP, CCDP
Sr. Internetworking Engineer
W: 401.456.1821 F: 401.456.0599 M: 508.982.8923
90 Royal Little Drive, Providence, RI 02904
www.guardent.com _____________________________________________________
G U A R D E N T
Security | Privacy | Data Protection
This archive was generated by hypermail 2.1.4 : Wed Aug 06 2003 - 06:52:41 GMT-3