Re: [squid-users] Performance tunning !

Henrik Nordström wrote:
> Joe Cooper wrote:
>
>
>>Do some reading on MTU. The simplest thing is probably to enforce a
>>small enough MTU on the cache network interfaces to make the problem
>>disappear...this probably isn't going to lead to the best performance
>>(larger MTU leads to higher network throughput and lower load on
>>equipment, all other things being equal), but it can probably fix the
>>errors you're seeing.
>
>
> Actually the simplest fix if your redirection method cannot support PMTUD is
> to disable the use of PMTUD. If you have dialup users or similar it is damn
> impossible to tell the smallest MTU you need to support to your clients
> unless you are willing to go for a rediciously small MTU value just to
> support the few that are using very small MTU (commonly done for better
> interactive performance on a shared link, such as someone doing SSH and
> downloading at the same time over a modem).
>
> The downside is that you MUST ONLY disable PMTUD for the links to your
> clients. You should not disable PMTUD on outgoing connections to the Internet
> or you may well find that you cannot reach parts of the Internet..

I'll buy that. Though this won't fix things in the case of the MTU
problem with WCCP (at least not in my experience). Of course, the MTU
only has to be dropped to 1476 (or somewhere around that, I don't recall
exactly) in that case, which does no real harm to throughput.

-- 
Joe Cooper <joe@swelltech.com>
Web caching appliances and support.
http://www.swelltech.com