From mboxrd@z Thu Jan  1 00:00:00 1970
From: Nick Pelling <nick.pelling@farncombe.com>
Date: Mon, 16 Mar 2015 16:00:21 +0000
Subject: Are there any alternatives to IFB for downlink shaping?
Message-Id: <1426521620621.27129@farncombe.com>
List-Id: <lartc.vger.kernel.org>
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To: lartc@vger.kernel.org


Hi everyone,

I'm trying to configure (OK, 'hack') a Linux-based Broadcom wireless gatewa=
y to prioritize the traffic between two groups of interfaces, e.g. where ho=
me traffic gets rate 80% ceil 95% prio 1, and where guest traffic (i.e. wl1=
) gets rate 15% ceil 60% prio 2.

I now have tc doing this beautifully on the uplink traffic (I use 'action s=
kbedit mark 1', why is this trick mentioned hardly anywhere?): but, like al=
most every other first time poster here :-) , I'm having no luck at all get=
ting this working for downlink traffic.

Specifically, I've put in a lot of work trying to get IFB working, but it s=
eems to be stitched too early in the packet processing chain to be any use =
for shaping a WAN interface's downlink traffic. Basically, my downlink band=
width stats stay resolutely at zero bytes / zero  packets, whatever I try. =
:-(

Are there any higher-level (i.e. device-level) configuration alternatives t=
o using IFB? It seems obvious to me that if I could insert any (fake, forwa=
rding-only) device at all between the WAN port and the rest of the system, =
then I would be able to use normal  tc egress shaping on the traffic going =
through it.

It strikes me that this would be something a tap device could do, for examp=
le: but I've never seen anyone discuss this anywhere on the web.

Anyway, I'm currently using eth3 for the WAN, so my (working) uplink traffi=
c shaping looks like this:-

eth0-2 / wl0 ---> br0 --->=A0 \
                       =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0  =A0 =A0=
 =A0 =A0+--->=A0[tc egress] eth3 --> [Internet]
wl1 =A0 =A0 =A0 =A0                =A0 =A0 =A0 =A0 =A0 --->=A0 /

For the downlink, however, I'm wondering if there might be a fake device I =
could configure in that serves only to forward packets. tap0?

eth0-2 / wl0 <--- br0 <---=A0 \
                        =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=
 =A0 =A0+ <---=A0fakedevice [tc egress] <--- eth3 <--- [Internet]
wl1                =A0  =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 <---=A0 /

I was hoping (of course) that IFB would be able to do this for me, but it d=
oesn't seem to want to play nicely. Am I missing something? All suggestions=
 and comments very much appreciated! :-)

Thanks very much, Nick