Daniel Musketa wrote:
Hello,
I'm trying to get lossless VoIP traffic over my 3000k/500k ADSL line. Shaping
outgoing traffic is no problem: I set total ceil for outgiong device (ppp0)
to 450kbit and put VoIP into highest prio class. Even during full upload the
voice is clean on the other end.
Now I tried to get the same result for incoming data. I attached HTB to eth1
where the incoming voip traffic is forwarded to. But even when I set the
ceiling for other traffic as low as 800kbit there are drop outs in incoming
voice while "full" downloading.
Could I setup HTB better than below? Should I reduce eth1's queue length (now
1000)? If yes, how?
If you use child qdiscs on classes then you set qlen with their params,
only people that don't bother need to play with txqueuelen.
... sfq perturb 10 limit 16 ....
I think in this case - gig eth and because of gso/tso then it would be
better not to shape on eth, but put ifb on ingress of ppp0. If you
really needed to use eth rather than ifb I would not use a default/ use
default 0 and only classify traffic from wan - unclassified goes
unshaped with htb. You use iptables so may prefer the latter - but it
looks like you could make tc rules to do the same for you in this case.
I would also give voip more of the bandwidth (rate) and make the lesser
classes borrow.
Sfq is really only for bulk - not that it should make much difference as
your voip class should never be backlogged, if set up as above.
To use ifb something like -
modprobe ifb
tc qdisc add dev ppp0 ingress
ip link set ifb0 up
tc filter add dev ppp0 parent ffff: \
protocol ip prio 10 u32 match u32 0 0 \
flowid 1:0 \
action mirred egress redirect dev ifb0
Then add your htb rules/filters to ifb0
FWIW 64kbit 50pps voip = 80kbit IP level, for my dsl pppoa = 116kbit at
atm level, for other pppoXs maybe 53*8*50 bit/s more. You can patch for
dsl(atm) overheads, or wait for an in kernel solution.
Andy.
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