From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Wed Apr 14 2004 - 15:12:32 GMT-3
David,
Your understanding is correct. The switching process occurs
after the routing table lookup. The reason that "in" can be more
efficient than "out" is a situation like this:
.Destination--E0--Router--E1--Source
. |
. E2
. |
. Cache Engine
A packet from a source located on E1 is received by the router
destined for a webserver out E0. A routing table lookup is performed,
the outgoing interface is determined to be E0, and the packet is
switched to interface E0. The router then looks at attributes applied
to the E0 interface, and sees that "ip wccp redirect out" is configured.
The router also knows that the cache engine is located on interface E2.
Assuming the packet is eligible to be cached it is switched from
interface E0 to E2 for delivery to the cache engine.
In the above case the packet is switched twice. Once to the
outgoing interface listed in the routing table, and then again to a
different interface in which the cache engine resides. If "ip wccp
redirect in" was configured on E1, the caching decision would be made
before the switching process. Therefore the packet would be switched
directly to E2, instead of to E0 and then back to E2.
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987 x 705
Outside US: 775-826-4344 x 705
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> David Hurtado
> Sent: Wednesday, April 14, 2004 9:59 AM
> To: marvingreenlee@yahoo.com; ccielab@groupstudy.com
> Subject: Re: Question about Tunnel interface and criteria of WCCP
>
> Hello Marvin,
>
> Would you mind to explain why the traffic will be switched twice if
you
> use
> "ip wccp redirect out"?
>
> The way i see WCCP, if i use "ip wccp redirect out", the router will
> redirect the request going out from the interface, which are
completely
> different from the requests that go into the interface.
>
> Maybe you are trying to explain that is better to use "ip wccp
redirect
> in"
> in the incoming interface than "ip wccp redirect out" in the outgoing
> interface, because in this way you don't have to make a IP route table
> check, find the ougoing interface and later redirect the request.
Using
> "ip
> wccp redirect in" in the incoming interface you redirect and don't
look
> for
> the ougoing interface.
>
> Is this what you wanted to explain?
>
>
> Please help me because me understanding of WCCP is very poor.
>
> Thanks a lot
>
>
> >From: Marvin Greenlee <marvingreenlee@yahoo.com>
> >Reply-To: Marvin Greenlee <marvingreenlee@yahoo.com>
> >To: Xy Hien Le <byme88@hotmail.com>
> >CC: ccielab@groupstudy.com
> >Subject: Re: Question about Tunnel interface and criteria of WCCP
> >Date: Wed, 14 Apr 2004 07:12:59 -0700 (PDT)
> >
> >1. If concerned about adding new addresses, ask the
> >proctor.
> >
> >2. With WCCP, In or Out specifies whether you are
> >doing ingress or egress filtering.
> >The command 'ip wccp redirect' tells the router what
> >traffic to redirect. It does not matter where the
> >cache server is. The cache server sets up a heartbeat
> >between itself and the router/switch, so that the
> >router/switch knows where the cache server is. If your
> >clients are on a certain interface, it is recommended
> >to use the 'ip wccp redirect in', so that traffic does
> >not have to be switched twice.
> >
> >See also:
> >WCCP Implementation PDF Presentation.
>
>http://www.cisco.com/warp/public/732/Tech/switching/wccp/docs/WCCP_Impl
em
> entation.pdf
> >
> >
> >Sample config for WCCP with a 3550 and a CE
>
>http://www.cisco.com/en/US/products/hw/contnetw/ps761/products_configur
at
> ion_example09186a0080160b28.shtml
> >
> >Cisco WCCP Presentations
>
>http://www.cisco.com/warp/public/732/Tech/switching/wccp/presentations.
sh
> tml
> >
> >
> >Marvin Greenlee, CCIE #12237
> >Network Learning, Inc.
> >Senior Technical Advisor
> >marvin@ccbootcamp.com
> >www.ccbootcamp.com
> >
> >--- Xy Hien Le <byme88@hotmail.com> wrote:
> > > Hi all,
> > >
> > > I have a couple questions:
> > >
> > > 1. In practice lab, I have encounter numbers of
> > > times that required creating a
> > > tunnel interface to solve issues. In some
> > > situations, I have to add additional
> > > IP address. My question is, does this allow in real
> > > lab scenario to add
> > > additional ip address?
> > >
> > > 2. What is the criteria of IN/OUT in WCCP, and when
> > > to decide which one to
> > > use?
> > >
> > > Any input is very much appreciated.
> > >
> > > Thanks in advance,
> > >
> > > Xy
> > >
> > >
>
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