How to prioritize VoIP traffic in the network

#!/bin/sh
TCOP="add"
IPTOP="-A"
if [ "$1" == "stop" ]; then
echo "Stopping..."
TCOP="del"
IPTOP="-D"
fi
#In the first section we take care of command line argument,
#if we run the script with sh ./name.sh stop then it will stop prioritizing,
#if run without any arguments, it will start to do what it's supposed to do.
#In this example we will use HTB (Hierarchy Token Bucket) algorithm to classify
#and prioritize traffic. This solution will give us the advantage of classes.
#This means we can create a class in which we can put VoIP traffic, a class
#in which we can put web and mail traffic and then prioritize traffic based on
#classes.
#Here is the diagram of our classes
#
#
# +---------+
# | root 1: |
# +---------+
# |
# +----------------------------+
# | class 1:1 |
# +----------------------------+
# | | |
# +----+ +----+ +----+
# |1:10| |1:20| |1:30|
# +----+ +----+ +----+
# |
# +--------+--------+
# | | |
# +-----+ +-----+ +-----+
# |1:100| |1:101| |1:102|
# +-----+ +-----+ +-----+
# 1:10 is the class for VoIP traffic, pfifo qdisc
# 1:20 is for bulk traffic (htb, leaves use sfq)
# 1:30 is the class for interactive and TCP SYN/ACK traffic (sfq qdisc)
# 1:20 is further divided up into different kinds of bulk traffic: web, mail and
# everything else. 1:100-102 compete for their slice of excess
# bandwidth, and in turn 1:10,20 and 30 compete for any excess above their
# minimum rates.
# which interface to throw all this on
IF=eth2
# ceil is 75% of max rate (768kbps)
# rate is 65% of max rate
# we won't let it go to 100% because we don't want the DSL modem
# to have a ton of packets in their buffers. *we* want to do the buffering.
RATE=576
CEIL=640
#VoIP traffic limit
VOIPLIMIT=448kbit
#syn/ack/fyn limit for interactive traffic like SSH
SYNACKL=32kbit
#http/mail limit
CLASS20R=96kbit
HTTPL=32kbit
MAILL=32kbit
OTHERL=32kbit
#You only need to change IF with your server network card name, and rate and ceil
#Next we create the root class, class 1
tc qdisc ${TCOP} dev ${IF} root handle 1: htb default 102
tc class ${TCOP} dev ${IF} parent 1: classid 1:1 htb rate ${RATE}kbit ceil ${CEIL}kbit
#Next we create the top layer class 10, 20, 30
#Each class has a guarantee of X (rate X) traffic,
#and can use a maximum of Y (ceil Y) if it is available
tc class ${TCOP} dev ${IF} parent 1:1 classid 1:10 htb rate ${VOIPLIMIT} ceil ${RATE}kbit prio 1
tc class ${TCOP} dev ${IF} parent 1:1 classid 1:30 htb rate ${SYNACKL} ceil ${RATE}kbit prio 2
tc class ${TCOP} dev ${IF} parent 1:1 classid 1:20 htb rate ${CLASS20R} ceil ${RATE}kbit prio 3
#Next we divide class 20 in 3 classes for "http mail" and everything else
tc class ${TCOP} dev ${IF} parent 1:20 classid 1:100 htb rate ${HTTPL}
tc class ${TCOP} dev ${IF} parent 1:20 classid 1:101 htb rate ${MAILL}
tc class ${TCOP} dev ${IF} parent 1:20 classid 1:102 htb rate ${OTHERL}
#Next, we assign the method used to shape our traffic for each class
tc qdisc ${TCOP} dev ${IF} parent 1:10 handle 10: pfifo
tc qdisc ${TCOP} dev ${IF} parent 1:30 handle 30: pfifo
tc qdisc ${TCOP} dev ${IF} parent 1:100 handle 100: sfq perturb 10
tc qdisc ${TCOP} dev ${IF} parent 1:101 handle 101: sfq perturb 10
tc qdisc ${TCOP} dev ${IF} parent 1:102 handle 102: sfq perturb 10
#Assign were the traffic with mark (handle ) X will go and prioritize the traffic (prio Y)
tc filter ${TCOP} dev ${IF} parent 1:0 protocol ip prio 1 handle 1 fw classid 1:10
tc filter ${TCOP} dev ${IF} parent 1:0 protocol ip prio 2 handle 2 fw classid 1:30
tc filter ${TCOP} dev ${IF} parent 1:0 protocol ip prio 4 handle 3 fw classid 1:100
tc filter ${TCOP} dev ${IF} parent 1:0 protocol ip prio 4 handle 4 fw classid 1:101
tc filter ${TCOP} dev ${IF} parent 1:0 protocol ip prio 4 handle 5 fw classid 1:102
#Mark the traffic using iptables
#Mark IAX2 with mark 1 .class 10
iptables -t mangle ${IPTOP} PREROUTING -p udp -m udp --dport 4569 -j MARK --set-mark 0x1
iptables -t mangle ${IPTOP} PREROUTING -p udp -m udp --dport 4569 -j RETURN
#Mark SYN,ACK,FIN SYN traffic with mark 2 class 30
iptables -t mangle ${IPTOP} PREROUTING -p tcp --tcp-flags SYN,ACK,FIN SYN -j MARK --set-mark 0x2
iptables -t mangle ${IPTOP} PREROUTING -p tcp --tcp-flags SYN,ACK,FIN SYN -j RETURN
#MARK HTTP and HTTPS traffic with mark 3 class 100
iptables -t mangle ${IPTOP} PREROUTING -p tcp --dport 80 -j MARK --set-mark 0x3
iptables -t mangle ${IPTOP} PREROUTING -p tcp --dport 80 -j RETURN
iptables -t mangle ${IPTOP} PREROUTING -p tcp --dport 443 -j MARK --set-mark 0x3
iptables -t mangle ${IPTOP} PREROUTING -p tcp --dport 443 -j RETURN
#Mark MAIL traffic class 101
iptables -t mangle ${IPTOP} PREROUTING -p tcp --dport 25 -j MARK --set-mark 0x4
iptables -t mangle ${IPTOP} PREROUTING -p tcp --dport 25 -j RETURN
#Mark everything else with mark 5 class 102
iptables -t mangle ${IPTOP} PREROUTING -j MARK --set-mark 0x5