Hi all ! I'm building a network appliance whose goals are to enhance Voip quality on 512/128k DSL links. But, i have a voice quality problem, and i think i'm doing something wrong, but i can't find what. Please excuse my terrible english, i'm french.
From what i've read, tc is the tool i need. I read the documentations,
readmes and lartc.org howto, and came to the following setup: NA = Linux-based network appliance (in fact a standard PC) A--[Switch]--[eth1 NA eth0]--[DSL modem] A = 1 pc and 1 ip phone on a 192.168.0.0/24 network on the other side, the DSL modem is a bridge-type, thus i have my internet ip on the NA eth0 interface. The DSL modem is actually a 15Mbit/1024Kbit ATM, but i want to limit the upload to 128Kbit/s, to test the Voip thing. My plan: HTB qdisc with overall rate at 128kbit, and 2 classes, one with prio 1 (for VoIP) and one with prio 2 (For other data), each of them rated a 1kbit/s and ceiled at 128kbit/s. And, on top of this, SFQ qdiscs for fairness. So : $TC qdisc add dev eth0 root handle 1: htb default 3 $TC class add dev eth0 parent 1: classid 1:1 htb rate 128kbit burst 6k $TC class add dev eth0 parent 1:1 classid 1:2 htb quantum 1600 rate 1kbit ceil 128kbit prio 1 $TC qdisc add dev eth0 parent 1:2 handle 2: sfq perturb 10 $TC class add dev eth0 parent 1:1 classid 1:3 htb quantum 1600 rate 1kbit ceil 128kbit prio 2 $TC qdisc add dev eth0 parent 1:3 handle 3: sfq perturb 10 And my packets are classified by the following in the iptables mangle table, forward chain: (my ip phone has 192.168.0.42, and pc 192.168.0.3) Chain FORWARD (policy ACCEPT 3400K packets, 9214M bytes) pkts bytes target prot opt in out source destination 284 118K CLASSIFY udp -- eth1 eth0 192.168.0.42 0.0.0.0/0 CLASSIFY set 1:2 284 118K RETURN udp -- eth1 eth0 192.168.0.42 0.0.0.0/0 12679 19M CLASSIFY tcp -- eth1 eth0 0.0.0.0/0 0.0.0.0/0 CLASSIFY set 1:3 12679 19M RETURN tcp -- eth1 eth0 0.0.0.0/0 0.0.0.0/0 (here a thing that i don't understand, is why i'm not classifying the packets with 2: or 3: ? when i do, the traffic is entirely stopped...i surely miss something here.) So, the packets get classified, and effectively, they are prioritized. _But_ i do hear some cuts in the voice that's sent through the NA, when i'm doing some uploads. (like some lazy wget --post-file=/tmp/some-big-iso-file.iso - Yeah i could use nc, but.. :) ) Shouldn't the voice be absolutely clean with this setup ? or am i missing something important ? For the sake of completeness: # tc -s -d qdisc show dev eth0 qdisc htb 1: r2q 10 default 5 direct_packets_stat 871 ver 3.17 Sent 25977039 bytes 18250 pkt (dropped 0, overlimits 28929 requeues 0) rate 0bit 0pps backlog 0b 28p requeues 0 qdisc sfq 2: parent 1:2 limit 128p quantum 1514b flows 128/1024 perturb 10sec Sent 162753 bytes 380 pkt (dropped 0, overlimits 0 requeues 0) rate 0bit 0pps backlog 0b 0p requeues 0 qdisc sfq 3: parent 1:3 limit 128p quantum 1514b flows 128/1024 perturb 10sec Sent 25678966 bytes 16999 pkt (dropped 0, overlimits 0 requeues 0) rate 0bit 0pps backlog 42392b 28p requeues 0 # tc -s -d class show dev eth0 class htb 1:1 root rate 128000bit ceil 128000bit burst 6Kb/8 mpu 0b overhead 0b cburst 1664b/8 mpu 0b overhead 0b level 7 Sent 26406423 bytes 17759 pkt (dropped 0, overlimits 0 requeues 0) rate 127968bit 10pps backlog 0b 0p requeues 0 lended: 17232 borrowed: 0 giants: 0 tokens: 92249 ctokens: -187751 class htb 1:2 parent 1:1 leaf 2: prio 1 quantum 1600 rate 1000bit ceil 128000bit burst 1600b/8 mpu 0b overhead 0b cburst 1664b/8 mpu 0b overhead 0b level 0 Sent 166201 bytes 388 pkt (dropped 0, overlimits 0 requeues 0) rate 856bit 0pps backlog 0b 0p requeues 0 lended: 388 borrowed: 0 giants: 0 tokens: 6986400 ctokens: 77500 class htb 1:3 parent 1:1 leaf 3: prio 3 quantum 1600 rate 1000bit ceil 128000bit burst 1600b/8 mpu 0b overhead 0b cburst 1664b/8 mpu 0b overhead 0b level 0 Sent 26278072 bytes 17396 pkt (dropped 0, overlimits 0 requeues 0) rate 127144bit 10pps backlog 0b 25p requeues 0 lended: 139 borrowed: 17232 giants: 0 tokens: -20775252 ctokens: -87749 Thank you all ! -- f00ty "Tact is the art of making a point without making an enemy." _______________________________________________ LARTC mailing list LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc
