From: ccie2be (ccie2be@nyc.rr.com)
Date: Fri Oct 22 2004 - 12:13:59 GMT-3
Sam,
Here's what you need to understand about wccp.
wccp is a protocol that redirects REQUESTS to the cache engine(s). Usually,
the requests are HTTP requests but don't have to be.
Now, consider how these REQUESTS flow through the router without wccp. A
REQUEST from a web browser comes in one interface and the router will route
that same REQUEST out another interface.
So, there are 2 points at which the router can redirect the REQUEST - as it
comes into the router or as it's about to go out of the router.
So, the thing to remember is that with WCCP, it's always the REQUEST that's
being redirected.
The interface which connects to the cache engine is NOT relevant to how the
command, ip wccp web-cache redirect, is used.
If you want to redirect REQUESTS as they come into the router, you use the
command with the IN option. If you want to redirect REQUESTS as they about
to leave the router, you use the OUT option.
Once the decision is made that you want to redirect HTTP (Web-cache)
REQUESTS, the next thing is to decide at what interface to implement the
redirection since it can be either on the input or the output interface and
which is better.
If, for example, you have web browsers off of 2 dozen ethernet interfaces
and one serial interface going to the internet, you cold configure the
command, ip wccp web-cache redirect in, on all 2 dozen ethernet interface by
entering the command 24 times or you could enter the command, ip wccp
web-cache redirect out just once on the serial interface. Both accomplish
the same thing - http REQUESTS will be redirected to the cache engine. But,
from a ease of configuration point of view, it's much easier to issue the
command just once on the serial interface.
However, from a router performance point of view, it's better to issue the
command on all 24 input interfaces.
Currently, IOS supports wccp version 2. Version 2 adds a number of new
capabilties to the original version 1 of wccp, but the redirect concept
remains the same. I think one of the new features of ver 2 is that now
besides redirecting http requests, other types of requests for other types
of sevices can be redirected as well to a cache engine or group of cache
engines, for example, ftp. I don't know or understand that much about how
to configure redirection for other services besides HTTP but I know that if
you're redirecting something else instead of using the keyword web-cache you
use a service number and the number 99 is reserved for reverse proxy
whatever exactly that is - I don't really know.
If you do a seach on cisco.com you'll find a few presentations on wccp which
go into more detail on these and other features.
HTH, Tim
----- Original Message -----
From: <samccie2004@yahoo.co.uk>
To: "'De Witt, Duane'" <duane.dewitt@siemens.com>
Cc: "'studygroup'" <ccielab@groupstudy.com>
Sent: Friday, October 22, 2004 10:22 AM
Subject: RE: WCCP direction ?
> In other words, in on the interface facing cache server ?
>
> Thanks
>
> Sam
>
> -----Original Message-----
> From: De Witt, Duane [mailto:duane.dewitt@siemens.com]
> Sent: 22 October 2004 16:06
> To: Scott Morris; samccie2004@yahoo.co.uk; studygroup
> Subject: RE: WCCP direction ?
>
> Hi
>
> With WCCP redirection you ONLY use redirect in OR redirect out on an
> interface. If you use both you will redirect return packets.
>
> The usual config is redirect in on your closest interface to the source
> traffic so that CEF can reduce the load on the router.
>
> Regards
> Duane
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Scott Morris
> Sent: Friday, October 22, 2004 3:40 PM
> To: samccie2004@yahoo.co.uk; 'studygroup'
> Subject: RE: WCCP direction ?
>
> You should have one or the other from a technical perspective.
>
> If you put both, then things may be confusing where the router redirects
> the
> previously redirected requests. (Not sure on this, as I haven't tested
> it,
> but it sounds like a bad idea!)
>
> Scott
>
> -----Original Message-----
> From: samccie2004@yahoo.co.uk [mailto:samccie2004@yahoo.co.uk]
> Sent: Friday, October 22, 2004 8:05 AM
> To: swm@emanon.com; 'studygroup'
> Subject: RE: WCCP direction ?
>
> Scott
>
> Thanks for the clear explanation :-)
>
> For D-Day, would Cisco accept one or the other or both. Or perhaps it is
> something that I need to deduct from the wording
>
> Regards
>
> Sam
>
> -----Original Message-----
> From: Scott Morris [mailto:swm@emanon.com]
> Sent: 21 October 2004 22:04
> To: samccie2004@yahoo.co.uk; 'studygroup'
> Subject: RE: WCCP direction ?
>
> The "redirect" is from the perspective of the router with regards to the
> http request being made.
>
> So:
>
> User --> e0/0 (router) s0/0 --> internet web server
>
> The web request is seen INCOMING on e0/0 and OUTGOING on s0/0. You may
> put
> either:
>
> E0/0: ip wccp web-cache redirect in
> S0/0: ip wccp web-cache redirect out
>
> The location of the web-cache itself is not part of the picture for this
> particular command.
>
> HTH,
>
>
> Scott Morris, MCSE, CCDP, CCIE4 (R&S/ISP-Dial/Security/Service Provider)
> #4713, JNCIP, CCNA-WAN Switching, CCSP, Cable Communications Specialist,
> IP
> Telephony Support Specialist, IP Telephony Design Specialist, CISSP CCSI
> #21903 swm@emanon.com
>
>
>
>
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> samccie2004@yahoo.co.uk
> Sent: Thursday, October 21, 2004 1:11 PM
> To: 'studygroup'
> Subject: WCCP direction ?
>
> Hi Group
>
> I still find it confusing to decide the direction of re-redirection when
> using caching engine.
>
> If a caching engine is on a LAN, would I redirect out to it so it caches
> my
> requests ?
> Or redirect in, so I accept response from it.
>
> I am inclined to use 1st explanation.
>
> Any thoughts ?
>
> TIA
>
> Sam
>
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