Network bottleneck

[Schoolies]

I'm trying to determine what is slowing down my Internet connection. At times it is slow as all heck but the majority of the time it is fine, so it appears something is using all of the bandwidth.

It is a simple 10 computer network with a T1 internet connection, Cisco 506 router and all unmanaged switches.

Can anyone recommend an easy tool (and of course cheap) to monitor the network traffic?

Thank you!

 

[drebo]

I like to use the scream test in this case. Look at the switches when the internet speed drops and unplug the fastest blinking light. When that person bitches, go over and see what he's doing. A T1 isn't exactly fast anymore, and depending on your router, if he's downloading a bit torrent or even listening to internet radio, it can have a relatively large impact.

 

[Googer]

It could be your DNS? Try switching to open DNS.

http://www.opendns.com/

 

[ScottMac]

Originally posted by: drebo
I like to use the scream test in this case. Look at the switches when the internet speed drops and unplug the fastest blinking light. When that person bitches, go over and see what he's doing. A T1 isn't exactly fast anymore, and depending on your router, if he's downloading a bit torrent or even listening to internet radio, it can have a relatively large impact.

Internet radio isn't that bad ... most stations I've seen aren't even 64k, frequently 32-40k or less. If you had a bunch of them, then I suppose it'd be an issue but if one Internet radio stream is killing the network, then there are other issues (up to and including a policy that permits Internet radio on the company LAN).

 

[JackMDS]

If 3 or more out of he ten are busy doing something that is Bandwidth Hogging the system would slow down.

Install a utility like Netstat on each computer and follow for few days the Bandwidth Habit.

http://www.analogx.com/content...twork/nsl/download.htm

In General.

The inexpensive way is to install a utility (as the above) and with cooperation of the users find the problem.

On the other hand a lot of time the problem occurs due to lack of users cooperation.

Under such circumstances the traffic need to be measured centrally which means setting an appliance or a computer that all the traffic flow through and can be evaluated.

 

[jlazzaro]

does your equipment terminate the T1? The 506 isn't a router, its a firewall.

try getting some interface utilization statistics on the PIX...look into something like MRTG. during times of high congestion, a pcap on the PIX with the capture command may give you more insight. depending on where the T1 terminates, you'll want to look into some type of QoS policy.