Hello everyone!
I was trying to do some traffic shaping to make http pages more
responsive while torrenting. So I decided to modify TOS value of packets
to have an affect on the default pfifo_fast qdisc.
I've the following iptable rules --
#DNS request
iptables -t mangle -A OUTPUT -o eth1 -p udp -m multiport --dports 53 -j
TOS --set-tos 0x10
#DNS response
iptables -t mangle -A PREROUTING -i eth1 -p udp -m multiport --sports 53
-j TOS --set-tos 0x10
#Incoming torrent connections
iptables -t mangle -A PREROUTING -i eth1 -p tcp -m multiport --dports
2000 -j TOS --set-tos 0x2
iptables -t mangle -A PREROUTING -i eth1 -p udp -m multiport --dports
2000,1900,2001 -j TOS --set-tos 0x2
#Mail server
iptables -t mangle -A OUTPUT -o eth1 -p tcp -d imap.googlemail.com -m
multiport --dports 993 -j TOS --set-tos 0x10
#HTTP(S)
iptables -t mangle -A OUTPUT -o eth1 -p tcp -m multiport --dports 80,443
-j TOS --set-tos 0x14
#iptables -t mangle -A OUTPUT -o eth1 -p tcp -m multiport --dports
80,443 -j TOS --set-tos 0x10
iptables -t mangle -A PREROUTING -i eth1 -p tcp -m multiport --sport
80,443 -j TOS --set-tos 0x14
#iptables -t mangle -A PREROUTING -i eth1 -p tcp -m multiport --sport
80,443 -j TOS --set-tos 0x10
There is an improvement, but it's so little that it feels like placebo,
making me doubt the above action. So are the actions correct?
man tc-prio has a table --
TOS Bits Means Linux Priority Band
------------------------------------------------------------
0x0 0 Normal Service 0 Best Effort 1
0x2 1 Minimize Monetary Cost 1 Filler 2
0x4 2 Maximize Reliability 0 Best Effort 1
0x6 3 mmc+mr 0 Best Effort 1
0x8 4 Maximize Throughput 2 Bulk 2
0xa 5 mmc+mt 2 Bulk 2
0xc 6 mr+mt 2 Bulk 2
0xe 7 mmc+mr+mt 2 Bulk 2
0x10 8 Minimize Delay 6 Interactive 0
0x12 9 mmc+md 6 Interactive 0
0x14 10 mr+md 6 Interactive 0
0x16 11 mmc+mr+md 6 Interactive 0
0x18 12 mt+md 4 Int. Bulk 1
0x1a 13 mmc+mt+md 4 Int. Bulk 1
0x1c 14 mr+mt+md 4 Int. Bulk 1
0x1e 15 mmc+mr+mt+md 4 Int. Bulk 1
But is there a difference between all TOS values which fall in a single
band?
I mean, does the behavior of pfifo_fast change if I change from 0x12 to
0x16? Cause I thought the qdisc to be simple, and a different behavior
for all of the above TOS values means pfifo_fast does a lot more than
just placing packets in 3 different queues.
Another question -- how do you get these TOS values? and what does -j
TOS --set-tos <HEX/DEC> do? Does it modify the 4 bits or the whole 8 bit
TOS value in the header, or does something completely different?
I'm running a custom kernel with Gentoo OS.
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