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Re: [LARTC] voip quality/bandwidth/latency techniques

To: dale <dale@czexan.net>
Subject: Re: [LARTC] voip quality/bandwidth/latency techniques
From: Andy Furniss <lists@andyfurniss.entadsl.com>
Date: Tue, 17 Jul 2007 02:24:39 +0100
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dale wrote:
I have voip quality issues I would like to minimize. I have a ~= 3M/384k (Comcast) cable modem and a CentOS based Linux router (SME 7, 2.6.9 kernel) with 5 NAT'd devices (3 PCs "DHCP", 2 Vonage adapters "static 10.10.2.10-11"). The quality problems are audio cutting out and popping. I tried the following (see below) based on a Cookbook example, but I still have audio popping. I have noticed popping corresponding with web browsing, etc.

Maybe you need to consider shaping/policing ingress traffic aswell.

  Any suggestions that may improve voip quality?
Also, are there any network metric capture/graphing tools that are helpful to analyze these type of issues. I'm thinking of a graph that shows various network metrics. I could watch the graph while using the phone and correlate graph spikes with audio pops. Thanks in advance for your help.

I don't use any graphing tools, but I would mark icmp as 1 aswell and have ping running while testing.


Dale



tc qdisc del root dev eth1
tc qdisc add dev eth1 root handle 1: htb default 12

Since you mark all unmarked ip as 3 you don't need default 12 - it will send arp to the worst class.

tc class add dev eth1 parent 1:  classid 1:1  htb rate 300kbit ceil 300kbit
tc class add dev eth1 parent 1:1 classid 1:10 htb rate 200kbit ceil 300kbit prio 0 tc class add dev eth1 parent 1:1 classid 1:11 htb rate 50kbit ceil 300kbit prio 1 tc class add dev eth1 parent 1:1 classid 1:12 htb rate 30kbit ceil 300kbit prio 2 tc filter add dev eth1 parent 1:0 protocol ip prio 1 handle 1 fw classid 1:10 tc filter add dev eth1 parent 1:0 protocol ip prio 2 handle 2 fw classid 1:11

unused?

tc filter add dev eth1 parent 1:0 protocol ip prio 3 handle 3 fw classid 1:12
iptables -t mangle -A PREROUTING --src 10.10.2.10 -j MARK --set-mark 0x1
iptables -t mangle -A PREROUTING --src 10.10.2.10 -j RETURN
iptables -t mangle -A PREROUTING --src 10.10.2.11 -j MARK --set-mark 0x1
iptables -t mangle -A PREROUTING --src 10.10.2.11 -j RETURN
iptables -t mangle -A PREROUTING -j MARK --set-mark 0x3

Andy.
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