Strange network problems...

[Marcus Williams]

Hi -

Anyone any good at diagnosing network problems? :)

We've started to get really odd network problems at work. It feels like 
a NAT problem but I havnt really got a clue as I cant track it down. The 
easiest way to reproduce it is from a browser - I can be happily 
googling when suddenly I'll get back an error from google saying my 
request wasnt understood. The strange thing about this is it appears to 
be someone elses request to a different site if that makes sense. So 
google is getting an HTTP request for something like /myspace/photo.jpg 
or a mangled version of my request.

Whats worse is occasionally these requests do work - so I can go to some 
random website and get an image back as the response (google.com the 
other day returned its favicon as the response for the root page, our 
netgear router returned one its css files in one of the admin frames on 
its page).

In other network tools its not as obvious (slow/broken connections etc) 
because you dont actually see the response as such, but its definitely 
happening. Switching to a different ADSL line doesnt fix it so I dont 
think its internet provider related. There dont appear to be any errors 
reported on the gateway NICs.

Anyone any ideas how to track it down?

Marcus