[altq 910] Re: Filters / filter intersection

[Kenjiro Cho <kjc@csl.sony.co.jp>]

Nicolas Christin wrote:
> 	I have yet another question, this time about filters. I read the
> documentation on the subject (in TIPS.txt) and I'm still a bit confused.
> What I want to do is set a filter specifying "all traffic going between IP
> address A and IP address B should be class 'high'". The traffic in
> question is TCP, and I want the ACKs (on the reverse path) to belong to
> class 'high'. If I use something like
> 
> 	filter fxp1 high A 0 B 0 0
> 
> data packets will indeed belong to class high, but since the TCP ACKs are
> sent from B to A, they won't match the filter. I would instead need to do
> something like
> 
> 	filter fxp1 high A 0 0 0 0
> 	filter fxp1 high 0 0 B 0 0
> 
> 	Unfortunately, the above doesn't work: the second filter will
> override the first one. Any suggestions? (Besides modifying the code
> of the parser, which I can do as a last resort, but would rather avoid if
> possible.) Also, I'd rather avoid having to define two classes with
> exactly the same properties...

You have to use disjoint filters.  For example,
	filter fxp1 high A 0 B 0 0
	filter fxp1 high B 0 A 0 0

But, usually, you have to configure another interface for the reverse
path since ALTQ controls only outgoing traffic.

-Kenjiro