Re: Mark traffic on one machine, match on another machine?

[Jack Bates <uo4zau@nottheoilrig.com>]

On 28/11/12 04:54 AM, Giles Coochey wrote:
> On 28-11-2012 05:25, Steven Kath wrote:
>>> Is there a way to mark traffic on one machine and match the
>>> mark on another machine? so I can classify traffic on the
>>> proxy server and shape it on the router?
>>
>> This question is a good example of the rationale for the
>> TOS/DSCP header on IPv4 packets. netfilter/iptables are
>> quite capable of matching and manipulating the DSCP field,
>> as are some proxy servers.
>> --
>
> +1 to above.
>
> Alternatively, you could route the packet from the proxy to a different,
> secondary IP on the router. The router could then shape all the traffic
> that arrives on the secondary IP. You can achieve the secondary IP with
> sub-interfaces, secondary IP in the same subnet, or separate VLAN
> interfaces
>
> I don't think there is any net-filter tagging, in the way that you can
> tag packets in rules while it passes internally through the proxy, that
> would be visible externally to the router.

Cool, thanks a lot for this advice Steven and Giles, our proxy server is 
Apache Traffic Server, so I started work on a simple "remap" plugin to 
set TOS/DSCP field: http://nottheoilrig.com/trafficserver/201211300/tos.cc

It should enable something like the following, in the Traffic Server 
remap.config:

   map http://gmail.com @plugin=tos.so @pparam=3
   map http://facebook.com @plugin=tos.so @pparam=7

But what about response traffic? Is there a way to copy the TOS/DSCP 
field to the response from the origin server?