[quagga-users 14095] Re: enabling ECN

durga c.vijaya.durga at gmail.com
Thu Aug 6 01:57:55 BST 2015

​i Mikael,
I am currently looking at setting buffer limits and observe the packets for
ECN flag. I am not yet planning to mitigate the effects of congestion by
implementing Fair Queueing,

The ecn flag as in /proc/sys/net/ipv4 is set to 2 which I think indicates
that the host responds an to incoming packets activated with ecn but
doesn’t trigger outgoing packets ​with ecn, I might have misunderstood it

Now that I understand that ecn settings are independent of quagga, I will
try to look more on ubuntu network settings to get the setup working.


On Wed, Aug 5, 2015 at 8:56 PM, Mikael Abrahamsson <swmike at swm.pp.se> wrote:

> On Wed, 5 Aug 2015, durga wrote:
> Hi Balaji,
>> Thank you very much. So enabling TCP ECN on the host machine is the right
>> way of propagating congestion notifications.
> Yes, but quagga only sets up routing, it doesn't set up anything else. So
> if you want the quagga running router to do ECN marking, you need to use
> whatever the operating system provides to set up queues that'll do ECN
> marking. If you're running recent Linux kernels, you can for instance use
> tc and set fq_codel as queuing algorithm on the interface.
> http://manpages.ubuntu.com/manpages/trusty/man8/tc-fq_codel.8.html
> #tc qdisc add   dev eth0 root fq_codel
> But this has nothing to do with quagga, quagga only programs the routing
> table, nothing else.
> --
> Mikael Abrahamsson    email: swmike at swm.pp.se
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