IPFW DUMMYNET: Several pipes after each other

[Ian Smith]

On Tue, 27 Jan 2009, Sebastian Mellmann wrote:
 > Ian Smith wrote:
[..]
 > > 00060: 192.000 Kbit/s    0 ms  30 KB 1 queues (1 buckets) droptail
 > >   0 tcp     192.168.0.64/1032    207.46.106.36/1863  1847947 563209421  0
 > >   0 141
 > > 00070:   3.072 Mbit/s    0 ms  40 KB 1 queues (1 buckets) droptail
 > >   0 tcp    207.46.106.36/1863     192.168.0.64/1032  2438211 3075075035  0
 > >    0 4550
 > >
 > > It's nearly all streaming rather than more interactive traffic, so
 > > pipe latency isn't so much of a concern.  Anyway, I rarely actually
 > > catch any traffic still in-queue, which you can stare at for tuning.

Just for reference re KES' message re ping times with a full queue: we 
only put established TCP traffic through these pipes; ICMP always, and 
UDP so far - unless/until it becomes an issue - are free-flowing here.

 > > Also, that's aggregate traffic, not per IP as with your masks (which
 > > look maybe wider than necessary, 0x0000ffff covers a /16) so you may
 > > wind up with lots of separate queues sharing a pipe, which may look
 > > very different.  How many hosts, how much memory to spare for each?
 > 
 > 
 > Is there any chance to get the dropped packets for _each_ queue (e.g.
 > logged to a file for further investigation)?
 > Does ipfw provide something here?

I don't know, I've only seen 'ipfw pipe show' results here.  If you have 
numbered queues specified too, I guess 'ipfw queue show' would be what 
to try; if that's any use you could append results to a file/s by cron?

 > I'm mainly doing experiments with different kinds of settings (bandwidth
 > limitations, variable delay, dropped packets probability etcpp.) and I
 > want to see how many packets are actually dropped by ipfw.

Happy experimenting .. soon you'll be the expert we can all consult :)

If you want to get deeper into it, freebsd-net is the appropriate list.

cheers, Ian