Kazaa/p2p on a LAN and ping problems

[Eric Timme]

Network topology:

LAN <==> FreeBSD Gateway <==> Internet

Gateway specifications:
FreeBSD overlord 4.8-STABLE FreeBSD 4.8-STABLE #0: Mon Sep 22 07:05:09 CDT 
2003
k6-233, 128MB ram
ipf packet filtering in place

Internet (cable):
256kb up
2.0mbish down

======

It seems an impossible task to limit Kazaa and other p2p (Kazaa especially) 
from accessing the Internet from a LAN, especially when you're sharing the 
LAN with other college age people. So, I've instead told them to limit their 
upstream to 5kB, which leaves a good amount of of the upstream pipe for web 
browsing.

However, whenever any p2p in the house is active pings on any external network 
degrade horribly, even if it's only a single host, and 20kb of my upstream 
bandwith remains. 

Wolfenstein servers that I pinged 30 on with no p2p activity on the LAN, for 
instance, begin to ping at 400-500 ; the situation is equally bad with MUDs 
and other ping reliant games such as Quake.

Is this normal? Is there anything I can do to fix the problem so that ping 
dependant games can be played while p2p apps are active on the LAN? Kicking 
the network cable out works late at night, and at times during the day, but 
it isn't a permanent solution. Limiting p2p from the LAN completely is not 
possible from my position.

A user on IRC mentioned he had no such problem with IPFW - if my problem isn't 
specific does that mean that my use of ipf is responsible for this behavior?

Thanks,
Eric