traffic analysis

[Robin Becker]

Our freeBSD 6.0 host is not yet in production, but appears to have outgoing 
traffic of around 140Mb/day; the http logs say 16 hits etc. The host provider 
said this

"The server is on a /20-network, and this leads to high amounts of
background traffic (ARP, broadcast, etc.). These traffic types are
likely to be the reason for most of your outbound traffic."

I'm not sure I follow this argument. Does this mean I'm responding to large 
number of spurious requests? The provider's analysis of the input volume is 
pretty small (0Mb).

Is there a tool that can give me some reasonable data on this sort of problem? 
Perhaps I need to close down some services etc.
-- 
Robin Becker