Re: Problems with some web sites (tuning?)
>>---- Original Message ----
>>Subject: Re: Problems with some web sites (tuning?)
>>Date: Sat, 28 Mar 2009 15:32:49 -0700
>>>> I don't know what could be causing this but the behavior might
>>>> suggest that the packets are undergoing a very high error rate.
>>>> timeout or "lockup" can indicate that the packets cannot be
>>>> reassembled at the destination (your computer) and the TCP
>>>> times out waiting for one or more missing packets.
>>>That makes sense to me, but why is it only a very few web sites? I
>>>haven't heard complaints about poor wikipedia access, so it appears
>>>that most other people don't have problems with that either. One
>>>I thought of is that maybe they have very tight timeout limits, and
>>>since I am on dialup, I often exceed those limits and they then drop
>>>packets. I have heard about a couple things(ECN and SACK?) that can
>>>cause problems with some sites, but I think I already have disabled
>>>them in the sysctl.conf settings I included in my original message.
>>>Any idea how I could trace something like dropped packets? Looking
>>>for the absence of something can be very difficult if I don't know
>>>what I should be looking for.
>>>Thanks for your suggestions.
>>>Carl Johnson firstname.lastname@example.org
> Oy dial up! Since others have not seemed to experience this and
> since you are on dial-up, this seems to point to your local dial-up
> connection-either excessive errors (a possibility) or substantial
> delay (also a possibility). Either one potentially requires (TCP)
> retransmission. A couple of tests to run (the second is a bit
> 1. Try the difficult web sites in the middle of the night when the
> ambient noise (and hence any errors) should be less
> 2. Move your computer to another location (a friends house across
> town perhaps) and try it from there.
Actually that brings up another possibility. I hadn't mentioned that
I also use wwwoffle (an offline www caching proxy), and I just
realized that seems to play a part. While offline, wwwoffle queues up
any http requests until I go online, and then it starts fetching them
at up to 4 at a time. The problem seems to mostly go away when I
fetch articles 1 at a time, so it appears that the congestion makes
the problem much worse. I am just going to experiment more with
reducing the number of parallel fetches for now. Having wwwoffle
fetch queued up jobs is convenient, so right now I'll just experiment
to find a reasonable compromise.
Thanks for your suggestions. I think they have given me some idea of
what is happening.
Carl Johnson email@example.com