Here are the symptoms, anyone know the solution?

[Shr00m]

Our Internet connection (dual T1's) has all the sudden started acting slow. Our ISP told us that we are only using 2/3 of our connection bandwidth but our users experiance slowdowns while surfing the net. One minute you can refresh our ISP's webpage and it pops up instantly 2 minutes from then you could do it again and it would take 10-15 seconds. We think it could be the firewall, but we are not sure how to test and get accurate results by sticking a normal workstation outside of our firewall.

Anyone have any ideas how to do this or suggestions on what to do?

EDIT: I've done traceroutes to our ISP and everything is fine excecpt it acts really slow for routes behind our firewall. Is this normal? Pings to these machines are 1ms, but for some reason traceroute times out sometimes, why is this?

 

[the]

first things first, if you suspect teh firewall, simply elimiante it. get on the otherside and do bandwidth tests and watch your ping times, do the same analysis from inside the firewall and compare notes. use the speakyeasy speed test tools, set up several ftp tests, ping and trace rt tests both inside of nad outside the firewall, about an hour of testing should give you more than anough data to compare back and forth.

if the trace routes are timing out fror routs behind your firewall its a good hunch to suspect it. dont rule out routers, what network hard ware are you running, how many users and how much traffic are you routing?

as a rule of thumb try to make both machiens the exact same, and after your dont testing, assume the box outside the firewall has been comprimised and reimage it. its overkill, but falls under best practices.