Ian Smith wrote: > That's a very good ipfw tutorial, given parts of it are a bit outdated > (FreeBSD 4.x) but it covers a lot of useful background. I just skimmed > lots of it now but nothing I read jarred, unlike the Handbook section. > > > If I choose the default (50 packets) it means that it takes approx. > 100ms > > (600kbits / 6144kbits) to fill the queue. > > So the question is: Which value to choose for the queue? > > It's going to depend on lots of things, your workload, upstream push .. > you could start with more like the default and adjust as necessary?
Sounds like a good idea. I'll just start with the default and see if works in my setup. > > > And you'll surely need a much larger queue for this pipe, at > 100Mbit/s. > > > > As already asked above: > > > > How do I know the queue is large or small enough for my needs? > > I'm never sure, so tend to experiment. How fast your hardware is and > kern.hz setting could be significant factors, as could be TCP/UDP mix > and other factors I know little about. Reducing reported packet drops > is about all I've used for a guide so far. This one is a FreeBSd 4.8 > box, a 2.4GHz P4 doing little but being a filtering bridge between a > 8192/384kbps ADSL link and nests of mostly XP boxes in 3 LAN groups: > > !ipfw pipe show | egrep 'tcp|bit' > 00010: 256.000 Kbit/s 0 ms 30 KB 1 queues (1 buckets) droptail > 0 tcp 192.168.0.23/1043 220.127.116.11/80 7196387 2897628161 0 > 0 9706 > 00020: 5.120 Mbit/s 0 ms 50 KB 1 queues (1 buckets) droptail > 0 tcp 18.104.22.168/80 192.168.0.23/1043 9977802 12858014698 > 0 0 63260 > > 00040: 96.000 Kbit/s 0 ms 20 KB 1 queues (1 buckets) droptail > 0 tcp 192.168.0.45/1037 22.214.171.124/443 2315107 299340364 0 > 0 2086 > 00050: 1.536 Mbit/s 0 ms 40 KB 1 queues (1 buckets) droptail > 0 tcp 126.96.36.199/443 192.168.0.45/1037 3279021 3802388928 0 > 0 22433 > > 00060: 192.000 Kbit/s 0 ms 30 KB 1 queues (1 buckets) droptail > 0 tcp 192.168.0.64/1032 188.8.131.52/1863 1847947 563209421 0 > 0 141 > 00070: 3.072 Mbit/s 0 ms 40 KB 1 queues (1 buckets) droptail > 0 tcp 184.108.40.206/1863 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. > > 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'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. > HTH, Ian Regards and thanks for the help so far, Sebastian _______________________________________________ email@example.com mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "freebsd-questions-unsubscr...@freebsd.org"