I'm trying to work out the best way to throttle a
network through a NetBSD router/firewall, and
am not sure of what's available to do this, and am
wondering if the list can help?

I've got a firewall/router doing PPPoE over a DSL
link, with two networks behind the firewall :

ugly ASCII diagram follows :


  Internet  ---- PPPoE ----  NetBSD box ---- Network A
                                 |
                              Network B


I want to be able to monitor network B, and when it
reaches a certain amount of traffic over a predetermined
period (1 month in this case) throttle it down to
56k or thereabouts (some arbitary speed) for its link out
through the DSL line.  The firewall/router is also doing
NAT, as nets A & B are RFC 1918 addresses.  Nets A & B are
10 or 100 Mb/s ethernet.

I was thinking of using IPF's "count" and a cronjob to
keep track of the traffic.

Is ALTQ good for this sort of throttling or do I need to look at some
other utility?

thanks

Carl