[LARTC] Bridge + leased line + tc

[Andy Furniss]

On Tuesday 13 January 2004  4:15 pm, Wouter Coppens wrote:
> Hi,
>
> I can't get traffic shaping working.
>
> This is my situation:
>
>
> 	     --------                       ------
> Net1 ----- |router|  -------------------- | TC | ----------- Net2
>            --------      leased line      ------
>
> 						   eth1    eth0
>
> We use the leased line for normal traffic but also for synchronisation
> between 2 servers. The leased line is 2mbit. The synchronisation
> generates too much traffic and uses completely the 2mbit capacity of the
> leased line. This is no problem during night, but we want to limit the
> synchronisation traffic during day (or in other words: the sync-traffic
> should get the lowest priority and the other traffic can use up to
> 2mbit).
>
> According to the documentation, you can only shape outgoing traffic. We
> took a PC (named TC) and put the network interfaces in bridge mode.
> The synchronisation happens from Net1 to Net2, so TC is after the leased
> line.
> Normally you would shape the outgoing traffic on eth0, but this doesn't
> work. We even tried to limit eth0 to 20kbit, but the synch-traffic
> completely fills the leased line and no other traffic gets through.
>
> We found a temporary fix by using IMQ with iptables:
> /sbin/tc qdisc del root dev imq0
> /sbin/tc qdisc add dev imq0 root handle 1: htb default 20
> /sbin/tc class add dev imq0 parent 1: classid 1:1 htb rate 2Mbit burst
> 6k
> /sbin/tc class add dev imq0 parent 1:1 classid 1:10 htb rate 64kbit ceil
> 787kbit
> /sbin/tc class add dev imq0 parent 1:1 classid 1:20 htb rate 2Mbit
> /sbin/tc qdisc add dev imq0 parent 1:10 handle 10: sfq perturb 10
> /sbin/tc qdisc add dev imq0 parent 1:20 handle 20: sfq perturb 10
> /sbin/tc filter add dev imq0 parent 1: protocol ip prio 18 u32 match ip
> dst 10.10.10.10 flowid 1:10	(10.10.10.10 is ip of server in Net2).
>
>
> Is there a better way to give the sync-traffic the lowest priority? If
> somybody starts a download it should get 2mbit and the sync-traffichttp
> should get the rest (if any).
>
> We would like to upgrade to 2.6, but imq is not maintained. Any help?

IMQ has been ported to 2.6 http://www.digriz.org.uk/jdg-qos-script/

Andy.