Measuring network traffic on the same interface, to different nets

["Sanjeev \"Ghane\" Gupta" <ghane@dotxtra.com>]

Folks,

I am running SQUID for a client, in transparent mode, woody, 2.4.19.  The
edge router sends all port 80 to me, I send out to the router on the same
interface.  I can capture total traffic on the interface.  The users are on
202.a.x.y.

What I need is a way to see:
    Traffic on eth0 to and from 202.a
    Traffic on eth0 to and from all other nets

This way, I can clearly see what reduction in traffic is occuring.  I can
get figures from SQUID, but these do not tally with the edge router's view,
which shows practically no difference between incoming and outgoing on the
port.  If SQUID is caching, outgoing should be more, as the SQUID acts as a
source for some objects, right?

Any way to do this?

--
Sanjeev