LARTC - Feb 2007 - tc filter matches ip fileds inside pppoe frames

I have a requirement which I guess it is not too unusually, however I
haven''t
quite figured out how to do it and couldn''t find any examples which
handle that.

I have made myself a Linux-based bridge, eth0 bridged with
eth1 to form br0.

In this bridge, I run ''tc'' script to handle QoS.

So far nothing unusual.

However, what''s different is that this bridge is sitted in between a
pppoe client
and pppoe server, ie pppoe frames are bridge between the Linux bridge, and 
I am interested to perform QoS on the pppoe frames, based on the ip tos setting 
of the ppp packets ( encapsulated inside the pppoe frames ).

For example, normal tc script :-

tc filter add dev ppp0 parent 1:0 prio 10 u32 \
     match ip tos 0x10 0xff \
     flowid 1:4

This will work on a ppp0 device because the ppp0 has ip packets flowing through 
it. Now in my bridge, there is no such device, I only have access to eth0 or
eth1,
how could I perform the same thing on devices such as eth0 or eth1, but matching
the ip TOS setting inside the pppoe frame ?

Best regards.




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Resent using text insted of html.
  ----- Original Message ----- 
  From: Ming-Ching Tiew 
  To: lartc@mailman.ds9a.nl 
  Sent: Monday, February 05, 2007 9:28 AM
  Subject: tc filter matches ip fileds inside pppoe frames


  I have a requirement which I guess it is not too unusually, however I
haven''t
  quite figured out how to do it and couldn''t find any examples which
handle that.

  I have made myself a Linux-based bridge, eth0 bridged with
  eth1 to form br0.

  In this bridge, I run ''tc'' script to handle QoS.

  So far nothing unusual.

  However, what''s different is that this bridge is sitted in between a
pppoe client
  and pppoe server, ie pppoe frames are bridge between the Linux bridge, and 
  I am interested to perform QoS on the pppoe frames, based on the ip tos
setting
  of the ppp packets ( encapsulated inside the pppoe frames ).

  For example, normal tc script :-

  tc filter add dev ppp0 parent 1:0 prio 10 u32 \
       match ip tos 0x10 0xff \
       flowid 1:4

  This will work on a ppp0 device because the ppp0 has ip packets flowing
through
  it. Now in my bridge, there is no such device, I only have access to eth0 or
eth1,
  how could I perform the same thing on devices such as eth0 or eth1, but
matching
  the ip TOS setting inside the pppoe frame ?

  Best regards.




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From: Ming-Ching Tiew
To: lartc@mailman.ds9a.nl
Sent: Monday, February 05, 2007 9:28 AM
Subject: tc filter matches ip fileds inside pppoe frames
> I have a requirement which I guess it is not too unusually, however I
haven''t
> quite figured out how to do it and couldn''t find any examples
which handle
that.
>
> I have made myself a Linux-based bridge, eth0 bridged with
> eth1 to form br0.
>
> In this bridge, I run ''tc'' script to handle QoS.
>
> So far nothing unusual.
>
> However, what''s different is that this bridge is sitted in between
a pppoe
client
> and pppoe server, ie pppoe frames are bridge between the Linux bridge, and
> I am interested to perform QoS on the pppoe frames, based on the ip tos
setting
> of the ppp packets ( encapsulated inside the pppoe frames ).
>
> For example, normal tc script :-
>
> tc filter add dev ppp0 parent 1:0 prio 10 u32 \
>     match ip tos 0x10 0xff \
>     flowid 1:4
>
> This will work on a ppp0 device because the ppp0 has ip packets flowing
through
> it. Now in my bridge, there is no such device, I only have access to eth0
or eth1,
> how could I perform the same thing on devices such as eth0 or eth1, but
matching
> the ip TOS setting inside the pppoe frame ?
Perhaps this will be one step closer to matching ip TOS inside the PPPOE
frame :-

 # tc filter add dev vlan0 parent 1:0 protocol 0x8864 prio 10 u32 \
     match u32 0x00100000 0x00ff0000 at  .... \
     flowid 1:4

Protocol 0x8864 refers to PPP_SES.

But the question where is the location of the TOS filed in the ip header
encapsulated inside the PPP frame ? What if the IP header is compressed
inside the ppp frame ?

Cheers