Weird Internal Network Problem - Help I'm going mad!!!

I have a really odd network problem and I just can't figure out what's
wrong.

My setup:-
I have a rack of servers, Win200 Server and Win2003 server, also 2 Linux
boxes. These servers are all connected to a Dell PowerConnect 5224
gigabit switch which is in turn connected to a Cisco PIX firewall which
is connected to the internet.

The internal network is setup as

192.168.7.10
192.168.7.20
..
..
192.168.7.100 etc

These IP addresses are mapped on the firewall to our range of external
IP's e.g.

192.168.7.10 -> 8x.xxx.xx.178
192.168.7.20 -> 8x.xxx.xx.179
etc

My problem is that for some reason traffic on the internal part of the
network does not always work. It seems totally random as to when it
works and when it does not.

e.g.
If I use remote desktop connection to a server from my home PC and bring
up a DOS prompt and ping any one of the servers on the internal network,
sometimes it will get a reply and sometimes it won't. Sometimes it will
get one reply and then will fail for the final 3 pings. Sometimes it
won't reply at all for 5 mins (-t option) and then it will reply
eventually. It doesn't seem to make any difference what server I connect
to remotely and what server I try and ping internally from there. What's
really odd though is say I connect to a server and try and ping
internally and I get no reply, if I also ping that same failed servers
external IP address from my home PC it will reply.

Anyone got any suggestions, I've swapped the switch for a spare, I've
changed all network cables, I changed the firewall and nothing has made
a difference.

Anyone got any suggestions?

ho <(E-Mail Removed)> wrote in news:45c36213$0$5406$(E-Mail Removed):

> me failed servers
> external IP address from my home PC it will reply.
>
> Anyone got any suggestions, I've swapped the switch for a spare, I've
> changed all network cables, I changed the firewall and nothing has made
> a difference.

Maybe you could try to connect your laptop to PIX's WAN port directly and
start to ping internally servers. If the ping reply is O.K, then you
could consider to change another ISP.

--
--------------------------------

Y. Chen [MCSE: Security 2003]

Yoning Tech
http://www.yoning.com

I agree.
But other things to look for.
Make sure you are running Cat5 or Cat5e when working with 100MB
Use premade cables. If you made them yourself, make sure you followed the
color code. Yes they have to be in order or colors and have to be straight
through. If you are using a PIX, pings have to be enabled, otherwise they
fail to ping from outside. Make sure you you have no looped network cables
on the switch.

on the local lan try pinging your servers with Ping xxx.xxx.xxx.xxx -l 65500
if it fails to ping large packet but passes small ping passes then
possible bad switch, network card, patch cable, or wiring in the wall not
certified Cat 5 or ends not wired correctly.

If your concerned about your ISP you can use pathping or tracert to locate
problem with ISP or your router.



"Y. Chen" wrote:

> ho <(E-Mail Removed)> wrote in news:45c36213$0$5406$(E-Mail Removed):
>
> > me failed servers
> > external IP address from my home PC it will reply.
> >
> > Anyone got any suggestions, I've swapped the switch for a spare, I've
> > changed all network cables, I changed the firewall and nothing has made
> > a difference.
>
> Maybe you could try to connect your laptop to PIX's WAN port directly and
> start to ping internally servers. If the ping reply is O.K, then you
> could consider to change another ISP.
>
> --
> --------------------------------
>
> Y. Chen [MCSE: Security 2003]
>
> Yoning Tech
> http://www.yoning.com
>