How can I find who is consuming the most bandwidth on a LAN?

Question

I have ADSL with 2Mbit bandwidth shared with my three roommates through a wireless LAN.

I found when playing Counter-Strike that the ping ranges from 20 to 300+; it's very unstable. Are there any tools that can help me find why it's so unstable? If one of my roommates was using download software, how would I know?

Answer 1

Do you have access to the router? If so and you are technically inclined and the router does not natively support it, you can install DDWRT or similar to give you the ability to bandwidth throttling/scheduling. This of course would probably create some animosity between you and your roommates should you not let them know ahead of time, but that is a discussion for another forum.

With DDWRT you can even use ntop to get bandwidth statistics for your network. This would be ideal in determining if you roommates are actually coming close to saturating your 2M line so that you can determine further action.

Answer 2

It's almost certainly the downloading. If you guys are going to share Internet, you have to actually share it. That means that when one person is doing something that requires low latency (like gaming) someone else can't do something that destroys latency (like running clustering downloaders).

The usual simple solution is to talk to the person downloading and explain to them that they need to limit their bandwidth in each direction to at most 80% of the maximum bandwidth they ever see. This will only reduce their transfer rates by 20% or so and it will keep the queues on the connection nearly empty rather than nearly full, preserving latency for applications like gaming.