[LARTC] Best method for filtering ACKs?

[LARTC] Best method for filtering ACKs?

[Stefan Gold]

Hello,

I'm wondering which of these filters is the best method for filtering ACK 
packages to achieve lowest delay possible on a dsl-link.

This one ist from the wondershaper from the lartc-site:

/sbin/tc filter add dev $EXTIF parent 1:0 protocol ip prio 0 u32 \
  match ip protocol 6 0xff \
  match u8 0x05 0x0f at 0 \
  match u16 0x0000 0xffc0 at 2 \
  flowid 1:10

Thats a suggestion from the german computer magazine c't:

iptables -A POSTROUTING -t mangle -o $EXTIF -p tcp -m length --length :64 -j 
MARK --set-mark 10
tc filter add dev $EXTIF parent 1:0 prio 0 protocol ip handle 10 fw flowid 
1:10

But why so difficult? Is there a reason against filtering ACKs like this?

iptables -A POSTROUTING -t mangle -o $EXTIF -p tcp --tcp-flags ACK -j MARK 
--set-mark 10
tc filter add dev $EXTIF parent 1:0 prio 0 protocol ip handle 10 fw flowid 
1:10

regards
Stefan
_______________________________________________
LARTC mailing list / LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/

Re: [LARTC] Best method for filtering ACKs?

[Ed Wildgoose]

Stefan Gold wrote:

>Hello,
>
>I'm wondering which of these filters is the best method for filtering ACK 
>packages to achieve lowest delay possible on a dsl-link.
>  
>

I think this is an excellent start for most stuff:
http://digriz.org.uk/jdg-qos-script/

The reason for all the frills is basically that some P2P protocols cheat 
and use ACK for actual transfer of data.  So I *think* both your 
examples, just try to filter only ACK's smaller than a certain size (128 
bytes is a good size), larger ones should be left alone and assumed to 
be bulk data.

Ed W
_______________________________________________
LARTC mailing list / LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/

Re: [LARTC] Best method for filtering ACKs?

[Stefan Gold]

Am Sonntag 20 Juni 2004 15:22 schrieb Ed Wildgoose:
> >I'm wondering which of these filters is the best method for filtering ACK
> >packages to achieve lowest delay possible on a dsl-link.
>
> I think this is an excellent start for most stuff:
> http://digriz.org.uk/jdg-qos-script/

That helped a lot. Thank you!

Stefan
_______________________________________________
LARTC mailing list / LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/