ssn_dk

Hi,
We have recently experienced some mysterious problems on our lan that
I hope you can help to clarify. Our setup is as follows:

1 linux box, running dns,dhcp and nat.
dhcp configuration:
172.1.0.1-172.1.0.254 subnet 255.255.248.0
cisco catalyst 2900 routers, with ips
192.168.3.10-192.168.3.15, subnet 255.255.255.0
~200 clients, primarily windows.

External internet access works fine, but the individual clients and
their workgroups in the LAN does not show up in windows (any version),
and LAN ping requests time out, from both windows and linux. Funny
thing is that the error is not completely persistent; sometimes I can
ping other clients and see their shares but only for a brief amount of
time. The only machine I can always ping locally is the gateway (the
linux server).

Everything worked like a charm until recently when the company
administering the server decided to change the dhcp ip range
(previously we all had 192.168.xx adresses). Due to bureaucracy and
other things I cant get to ask that company about the error - we live
at a college dormatory, they dont really listen to us..

Do you have any idea what could possibly cause this? I dont really
know how windows sharing works, but I suspect it uses broadcasts. Why
ping requests won't work baffles me even more. If I setup my laptop
and desktop machines with static ip's, ping only works if I disconnect
the cable that connects my personal switch with the rest of the lan.
Is it related to the fact that the routers are now on an entirely
different "ip set" than the clients?
Can either the server or the routers have been reconfigured in a way
that disallows this kind of network traffic?

Regards,
Mr. Soren Nielsen
Denmark

keith wansbrough

ssn_dk@hotmail.com (Soren S. Nielsen) writes:

Don't know the answer to most of your questions, but I have
experienced a situation where it seemed that Windows (XP) didn't
respond to pings unless QoS was turned on. Also if you have Internet
Connection Firewall on, you need to allow ICMP echo requests in.

HTH.

--KW 8-)
--
Keith Wansbrough <kw217@cl.cam.ac.uk>
http://www.cl.cam.ac.uk/users/kw217/
University of Cambridge Computer Laboratory.