[plug] Network query

[Luke Dudney]

Firstly I would have to ask if this chain of events is able to be
reproduced exactly each time the problem occurs? If not, then your
description is really not much help as it could have been a random
failure (solar flare, parallel processor running perpendicular etc)

I've traced a similar problem to this back to bad cabling -- I could see
arp requests on the wire but not any upper layer traffic. Re-crimping
the connections solved the problem. 

When everything is working correctly, do some ping and throughput tests.
Are you able to sustain LAN speeds over long periods with no packet
loss?

Cheers
Luke

On Tue, 2003-11-04 at 15:04, Bret Busby wrote:
> Hello, all.
> 
> A LAN is as follows:
> 
> 
>     Server/firewall/gateway
>              |
>              |
>    _____________________
>    |         |         |
>    |         |         |
> Client1   Client2   Client3
> 
> 
> The server is running RH 6.2, Client1 is running RH 6.2, Client2 is 
> running RH 7.3, and Client 3 is running Debian (testing).
> 
> The server is shutdown at night (dodgy power supply/fan), and Client2 is 
> left running overnight. Client1 and Client3 are not running.
> 
> This procedure is done over a number of nights, without any problem. 
> Then, due to a decreasing free disk space on the server, archived log 
> files (*.<x>.gz) are deleted from /var/log, on the server.
> 
> Then, the server/firewall/gateway is connected to the Internet (as it 
> is, almost each day), and fetchmail downloads email messages which are 
> sorted by postfix, in to mailboxes.
> 
> Then, using Client2, user tries to access mail (using PINE) on server, 
> as is usual. Attempt fails.
> 
> User tries to ping server from Client2. Destination host unreachable. 
> User tries to ping Client2 from server. Destination host unreachable. 
> User pings server from server, and, Client2 from Client2; pings are 
> successful for pinging same machine. User boots up Client1, and tries to 
> ping Client2 then server, from Client1, and tries to ping Client1 from 
> Server then from Client2. Destination Host unreachable in each case. 
> User pings Client1 from Client1; pings are successful for pinging same 
> machine. User "jiggles connections at network cards", to find whether it 
> makes any difference. No difference. User boots up Client3, and pings 
> server. Client 3 successfully pings server, and then server successfully 
> pings Client3. User then pings Client2 from Client3, then pings Client3 
> from Client 2, and server from Client2 and Client2 from server. pings 
> are each successful. Client1 ping is similarly "awoken". Client3 is 
> shutdown, and pings between remaining live computers, are successful, 
> each way.
> 
> This all happened within the last couple of hours.
> 
> Any ideas as to what has happened, and why?
> 
> Thanks in anticipation.

_______________________________________________
plug mailing list
plug at plug.linux.org.au
http://mail.plug.linux.org.au/cgi-bin/mailman/listinfo/plug