[LARTC] QoS for Voip.

[Alessandro Ren]

Thanks for the tips Brian,     Actually, I have many sorts of links, line PPOE ADSL, PPPOA ADSL which a use PPTP over PPOA relay, radio links that connect in the  ethernet interface and cable modems.     To change the SFQ queue size I must recompile de kernel? I think a saw some messages talking about that.     One other thing, I have the 1:10 a   1:20 class, let's assume there is no voip traffic and all bandwidth is being consumed and it is in the other class. When the voip traffic starts, there is  a inicial delay untill the 1:20 class starts to free bandwidth to the 1:10 class, as I've noticed. Should I change the burst and cburst parameters to get a better response or just make de queues smaller?       Thanks. Brian Carrig wrote: On 16 Jul 2004 at 13:35, Alessandro Ren wrote: Hello Brian, This is the basis for the wshaper. I have only two classes and I put voip on the 1:10 class and the rest in the 1:20. I am not listing here, but I have the rule marking packets and sorting then into classes, actually, I just put one port into the 1:10 class, that's the voip port and nothing else. I really want to keep the best quality I can for voip, without bandwidth waste., because, if a page takes 1 seconds longer do load is ok, but if a voip packet starts to get delay, we got a problem, I think, I must have no queue for voip packets, all packtes should be forwarded as soon as they get to the box, right? You do actually have a queue for VoIP, as you implement SFQ for both the 1:10 and 1:20 classes. To the best of my knowledge the default setting for this queue is 128 packets. This may be too large for VoIP if latency is a concern so I would suggest making this queue much smaller (limit option). Unfortunately without knowing the particulars of your link I am unable to suggest a figure but have play around and see what suits. Regards Brian # tc qdisc add dev $DEV root handle 1: htb default 20 # shape everything at $UPLINK speed - this prevents huge queues in your # DSL modem which destroy latency: tc class add dev $DEV parent 1: classid 1:1 htb rate ${UPLINK}kbit burst 6k # high prio class 1:10: tc class add dev $DEV parent 1:1 classid 1:10 htb rate $[4*$UPLINK/10]kbit \ burst 6k prio 1 # bulk & default class 1:20 - gets slightly less traffic, # and a lower priority: tc class add dev $DEV parent 1:1 classid 1:20 htb rate $[6*$UPLINK/10]kbit \ ceil $[10*$UPLINK/10]kbit burst 6k prio 2 # all get Stochastic Fairness: tc qdisc add dev $DEV parent 1:10 handle 10: sfq perturb 10 tc qdisc add dev $DEV parent 1:20 handle 20: sfq perturb 10 Brian Carrig wrote: We run something similar allowing customers to place traffic into gold, silver or bronze classes. I reserve a fixed amount of bandwidth for each class and allow them to borrow (I hate the idea of bandwidth going to waste). However, excess bandwidth is offered preferrentially to gold, then silver before being offered to bronze. Because p2p and other bw consuming traffic are unlikely to be in the gold and silver classes (they cost more) there haven't been any problems. I haven't really looked at the wondershaper script in much detail, how is voip traffic prioritised? Regards Brian On 16 Jul 2004 at 12:19, Alessandro Ren wrote: I've been using a altered version of the wshaper script to priorize voip traffic for my customers. I'd like to know if someone in the list has any tips on QoS for voip, if someone has done some experimentation. I am using HTB and if someone on the LAN uses a p2p program, I started to noticed in the voip, with cuts, jitter and lag. If a reserve a fixed amount of bandwitdh not letting anyonbe borrow, it works fine, but then if noone is using voip, I have bandwidth going to waste. I think I need some fine tunning oin the HTB parameters, but I am not sure sure about that.