[LARTC] Sharing a DSL between 40 subnets with htb

[Flemming Frandsen <ff@nrvissing.net>]

I have a network with around 40 /24 subnets that shares a common DSL, 
this cries out for shaping so here I am trying to make it work as my 
first tc project.

I have managed to cargocult some snippets from this list and tried to 
come up with a config, but there are a few things that I'd really like 
some input on:

1) Are the NAT'ed addresses available in the PREROUTING table of eth0?

2) If not then can I have the iptable --set-mark stuff in the tables
    for one interface and use the mark in tc on another interface?

3) Is it possible to filter on the routing table in stead of the
    --set-mark? so all traffic going to a certain router gets
    filtered into the same htb?

4) Does this look at all sane?


Note: I didn't generate the 40 classes for this example.

#!/bin/sh -x

#This is a generated traffic shaper script that is supposed to evenly
#share out a common DSL line between a number of subnets on:
#eth0: The DSL line.
#eth1: The 10.48.0.0/12 net, which contains 20 user subnets.
#eth2: The 10.16.0.0/12 net, which contains the server net.
#ath0: The 10.32.0.0/12 net, which contains 20 user subnets.

#Root htb that all the traffic is going to go through:
tc qdisc add dev eth0 root handle 1: htb default 0x42
tc class add dev eth0 parent 1: classid 1:1 htb rate 700kbit burst 6k

#Default class for everything not matched by the firewall rules:
tc class add dev eth0 parent 1:1 classid 1:42 htb rate 600kbit\
                                               burst 15k prio 0
tc qdisc add dev eth0 parent 1:42 handle 42: sfq perturb 20

#Have the bucket that traffic gets dropped into
#be determined by the firewall mark
#btw: --set-mark 0xbabeface maps to class id babe:face
tc filter add dev eth0 parent 1: protocol ip prio 1 handle 1 fw

#Start the table for classifying traffic:
iptables -t mangle -N to-dsl

#Hook up the classification table to the interface
iptables -t mangle -A PREROUTING -o eth0 -j to-dsl


#Here are all the buckets for the user subnets

#Adding subnet: 10.16.0.0/24
iptables -t mangle -A to-dsl -s 10.16.0.0/24\
              -j MARK --set-mark 0x11000

tc class add dev eth0 parent 1:1 classid 1:1000\
               htb rate 600kbit burst 15k prio 10

tc qdisc add dev eth0 parent 1:1000 sfq perturb 20


#Adding subnet: 10.32.0.0/24
iptables -t mangle -A to-dsl -s 10.32.0.0/24\
              -j MARK --set-mark 0x12000

tc class add dev eth0 parent 1:1 classid 1:2000\
               htb rate 600kbit burst 15k prio 10

tc qdisc add dev eth0 parent 1:2000 sfq perturb 20


#Adding subnet: 10.32.1.0/24
iptables -t mangle -A to-dsl -s 10.32.1.0/24\
              -j MARK --set-mark 0x12001

tc class add dev eth0 parent 1:1 classid 1:2001\
               htb rate 600kbit burst 15k prio 10

tc qdisc add dev eth0 parent 1:2001 sfq perturb 20


#Adding subnet: 10.32.2.0/24
iptables -t mangle -A to-dsl -s 10.32.2.0/24\
              -j MARK --set-mark 0x12002

tc class add dev eth0 parent 1:1 classid 1:2002\
               htb rate 600kbit burst 15k prio 10

tc qdisc add dev eth0 parent 1:2002 sfq perturb 20


#Adding subnet: 10.32.3.0/24
iptables -t mangle -A to-dsl -s 10.32.3.0/24\
              -j MARK --set-mark 0x12003

tc class add dev eth0 parent 1:1 classid 1:2003\
               htb rate 600kbit burst 15k prio 10

tc qdisc add dev eth0 parent 1:2003 sfq perturb 20


#Adding subnet: 10.48.0.0/24
iptables -t mangle -A to-dsl -s 10.48.0.0/24\
              -j MARK --set-mark 0x13000

tc class add dev eth0 parent 1:1 classid 1:3000\
               htb rate 600kbit burst 15k prio 10

tc qdisc add dev eth0 parent 1:3000 sfq perturb 20


#Adding subnet: 10.48.1.0/24
iptables -t mangle -A to-dsl -s 10.48.1.0/24\
              -j MARK --set-mark 0x13001

tc class add dev eth0 parent 1:1 classid 1:3001\
               htb rate 600kbit burst 15k prio 10

tc qdisc add dev eth0 parent 1:3001 sfq perturb 20


#Adding subnet: 10.48.2.0/24
iptables -t mangle -A to-dsl -s 10.48.2.0/24\
              -j MARK --set-mark 0x13002

tc class add dev eth0 parent 1:1 classid 1:3002\
               htb rate 600kbit burst 15k prio 10

tc qdisc add dev eth0 parent 1:3002 sfq perturb 20


#Adding subnet: 10.48.3.0/24
iptables -t mangle -A to-dsl -s 10.48.3.0/24\
              -j MARK --set-mark 0x13003

tc class add dev eth0 parent 1:1 classid 1:3003\
               htb rate 600kbit burst 15k prio 10

tc qdisc add dev eth0 parent 1:3003 sfq perturb 20

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