Re: squid cache

Travis Johnson wrote:
 
> I've noticed in the squid archives you seem to have alot of experience
> with squid and cisco.

I wouldn't say that. I only hack on Squid on my spare time as
recreation, I do not (currently) run it.

> We are trying to start a squid cache for our ISP.

Good.

> Using the cisco redirection seems logical, but at the same time seems
> like it will cause twice the amount of traffic on the ethernet port? Is
> that correct?

It depends. If your Squid is on another ethernet port than your clients
then your router will route all cache misses twice, one time from the
internet to the cache, and one time from the cache to the clients. If
your Squid is on the same ethernet port as the clients then only the
tiny fraction of the traffic that flows from the clients to the internet
will be doubled. Route-maps are not bi-directional, they only affect the
traffic that are routed throught the router.

You should also know that cache->client MTU discovery does no work when
using transparent proxying so you propaply need to disable MTU discovery
on the cache box, or some clients may experience strange effects (causal
hung traffic).

There are other ways to accomplish similar goals. One very effective one
is to use a route map to redirect the traffic to a small server which
returns a page giving detailed instruction on how to configure the proxy
settings (preferably using a PAC file to simplify things and future
maintaince) and why caching is good for the customer. This way you
avoids all the technical issues of running transparent proxying, and
also most of the political ones too.

> Also, have you had any experience with squid v2.2? Is it recommended for
> a very large squid cache?

Is 2.2 released yet? Last time I looked it was only in pre-release state
(2.2.PRE2). I don't recommend a pre-release for any production cache,
and 2.2.PRE2 has known errors of which some is 2.2.PRE specific.

In general however every new release improves things, so I recommend
trying to always have a recent version running a few weeks after it has
been released (== RELEASE or PATCHx). My current recommendation is
2.1.PATCH2 + recommended patches listed on my Squid page
http://hem.passagen.se/hno/squid/, or 2.2 some time after it has been
released (allow some time for testing of the release before deploying it
on a main cache).

And please, send future questions to squid-users mailinglist.

--
Henrik Nordstrom
Spare time Squid hacker