I am currently using the ultimate-tc script from http://lartc.org/howto/lartc.cookbook.ultimate-tc.html and I want to make sure that internet radio packets (mp3 streaming audio) will always get through no matter what. I have added some iptables commands like this: iptables -A OUTPUT -t mangle -p tcp --dport 8000 -j TOS --set-tos Minimize-Delay iptables -A OUTPUT -t mangle -p tcp --sport 8000 -j TOS --set-tos Minimize-Delay with the aim of marking the streaming audio packets so that they will get a higher priority: but I'm not sure if this is needed or exactly how it works! Some audio streams come in with the incoming packets marked [tos 0x40] and the outgoing packets marked [tos 0x10] (according to tcpdump) but not all. The ultimate-tc script ends with these ingress rules: ########## downlink ############# # slow downloads down to somewhat less than the real speed to prevent # queuing at our ISP. Tune to see how high you can set it. # ISPs tend to have *huge* queues to make sure big downloads are fast # # attach ingress policer: tc qdisc add dev $DEV handle ffff: ingress # filter *everything* to it (0.0.0.0/0), drop everything that's # coming in too fast: tc filter add dev $DEV parent ffff: protocol ip prio 50 u32 match ip src \ 0.0.0.0/0 police rate ${DOWNLINK}kbit burst 10k drop flowid :1 This will drop packets to keep the download rate just below the maximum capacity of the link: which will keep the ISP's queue empty and improve latency. But I am concerned that if there are a *lot* of other download streams going at the same time as my audio stream, then these rules may drop lots of packets from the audio stream and cause it to skip. Should I add rules to drop audio stream packets at ${DOWNLINK}kbit rate and drop all other traffic at $[9*$DOWNLINK/10]kbit rate, in the same way that ultimate-tc does for outgoing traffic? If so, what should the rules look like? Something else I don't understand about ultimate-tc is that the high priority class gets a rate of ${UPLINK}kbit and the low priority class gets $[9*$UPLINK/10]kbit: but doesn't the rate refer to traffic *in that class*. Traffic-Control-HOWTO Section 7.1.5. (Rules) says: "Ideally, the sum of the rates of the children classes would match the rate of the parent class, allowing the parent class to distribute leftover bandwidth (ceil - rate) among the children classes." but this isn't the case for the ultimate-tc script. -- Martin Martin.Ward@xxxxxxxxxxxx http://www.cse.dmu.ac.uk/~mward/ Erdos number: 4 G.K.Chesterton web site: http://www.cse.dmu.ac.uk/~mward/gkc/ _______________________________________________ LARTC mailing list / LARTC@xxxxxxxxxxxxxxx http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
