Re: modprobe ifb

Linux Advanced Routing and Traffic Control

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Hi
i think the problem is red only works when there is congestion
(queue),but the only limit on ingress is speed of kernel (no limit). RED
is not for and cannot limit traffic rate. That is why it wouldn't work
here, unless combined with something to shape the traffic rate. (tbf or
htb here)
What you might want to do is to shape traffic with htb as you did, and
use red inside htb, not to do tail-drop.
Tbf would be easier for shaping, but i don't know if combining tbf and
red is possibe. (probably not)

from man tc-red:

bandwidth
   This rate is used for calculating the average queue size after
   some idle time. Should be set to the bandwidth of your interface.
   Does not mean that RED will shape for you! Optional.


Ruben Porras wrote:
I'm trying to set up a traffic control on ingress attaching a egress qdisc to
the ifb device. The idea is to use a RED algorithm instead of policing
the incoming traffic. After trying with tc-red and not obtaining the
expected results, I decided to try with something easier, and use htb
as bottleneck:

ifconfig ifb0 up
tc qdisc del dev $dev ingress
tc qdisc del dev ifb0 root

tc qdisc add dev $dev ingress
tc filter add dev $dev parent ffff: protocol ip prio 10 u32 \
  match u32 0 0 flowid 1:\
  action mirred egress redirect dev ifb0


(1) tc qdisc add dev ifb0 root handle 1: htb default 1
(2) tc class add dev ifb0 parent 1: classid 1:1 htb burst 0 rate 112kbit

Now I generate some traffic:

$ scp user@host1:~/reallylargefile .
reallylargefile                          0%   64KB  12.4KB/s 7:52:29

and I get the expected results, if instead of htb I use something like
RED, changing lines (1) and (2) with

tc qdisc add dev ifb0 root handle 1: red limit 256000 min 1 max 32000
avpkt 1 burst 1 probability 0.8 bandwidth 512

I don's see any dropped packets at all. (I know that the values of min,
avpkt and burst are extremely low, and that probability is extremely
high, but I just tweakeed them hopping to see dropped packets)

Did I completely misunderstod the how red works?

Thank you.

i am a newbie here, so if i am completely wrong, then i am sorry.
_____________
Best regards
John Default


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