Re: [ProgSoc] Slow Network Response from FreeBSD

[vik <vik@nospam.progsoc.org>]

> The server is slow to respond to connections on ports 110 and 25 from most
> computers on the internal network. There is one that it responds to
> immediately, the rest connect immediately but take between 30 and 60
> seconds to actually bring up the initial welcome string. The computer that
> has an OK response time is not running dhcp and the others are, however I
> have tried setting static IP configs on the others and it has not changed
> the delay. The problem seems to have just spontaneously started one day,
> with no known configuration changes or anything on the server around that
> time.
> 
> I have tried reinstalling qpopper (the POP3 package on the server) with no
> success. The server responds fine as a gateway, i.e. serving web requests
> from the internal network to the internet.
> 
> At this point I am somewhat perplexed as to what to do. My next step would
> be to replace the internal network card but it doesn't stand to reason
> that that should achieve anything.
> 
> I have checked the logs, process list, memory and processor usage and all
> seem to be performing well.
> 
> Has anyone seen this sort of thing before / got any suggestions?

I remember having seemingly inexplicable network delays because of a 
lack of DNS server; when anything was requested of the server, it would 
attempt a reverse DNS lookup on the client; since it was an internal 
network without DNS, this failed and slowed everything down. My solution 
was to install & configure a DNS server. However, this is unlikely to be 
ur problem unless ur logs are full of failed reverse DNS lookups. what 
loglevels are ur daemons running at? increase these to log everything?

But for it to start spontaneously is most odd. So, I reckon try changing 
the NIC for a known working one. I have had some dodgy NICs which work 
but slow everything down a heap. Althought for it to server one computer 
fine and not the others is most odd, suggesting it is not the NIC.

Have u looked at network usage? collision lights on the hub? for that 
matter even the lights on the NIC when it is idle? a network monitor on 
the server may help; packet sniffing may also yield clues.

vik


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