Re: Suggestion to improve it

From: Chris Fedde <>
Date: Wed, 04 Sep 1996 14:15:18 -0600

In message <> Lars Fenneberg writes:
> I thought of it this way: if there is a cache hit, then the connection
> is not established (most of the time, when the DNS entry is not
> expired). But when there is a miss, the page is fetched directly. This
> should already cut down telephone charges. But you're right that this
> might not be enough.
> The problem with the "dial by hand" senario is that the user might not
> get the desired page even if it is in the cache, because the DNS entry
> has expired.

It's really more complex than this. Squid is going to do a HEAD
for each client request on just about every object in the cache.
This is so that the cache can be sure that it is sending the correct
stuff to the client. Most HTTP objects in the cache do not have
an Expires: header and so squid can not determine if the object
in the cache is the most current object. The HEAD request allows
squid to compare the Last-Modified: or at worst the Date: header.

Squid is not really the best choice for operating in an unconnected
environment. It can however be used to help improve the performance
over a slow or expensive link. Here is how I would do it:

    - Make sure there is a local caching DNS server and that all
    clients are configured to use it.
    - Set up the dial link to connect on packet requests and set the
    timeout to be short (say 5 to 10 minutes).
    - Set the squid positive_dns_ttl to zero (0) so that it will always ask
    the name server for addresses. This is a workaround for a bug in the
    squid 1.0.X ipcache code

This setup should minimize the amount of time that the connection
stays dialed and should maximize local performance. From here the
next step would be to get a dedicated 28.8K modemport connection
to your ISP and leave the modem dialed 24 hours/day. Here in
Colorado this is around US$200/month. That may be a bit too steep for
the casual user.

good luck
Received on Wed Sep 04 1996 - 13:18:49 MDT

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