[Codel] ingress rate limiting

Dave Taht dave.taht at gmail.com
Wed Jan 2 13:56:09 EST 2013


I know we have a tendency to focus on just one side of the queue. In
asymmetric networks, both sides get important.

Attached are some plots I took yesterday (from the rrul test prototype
which measures ping rtt in combination with 8 up/down tcp streams) of
normal comcast behavior, the prototype of what I'm calling "cake" on
both ingress and egress, and same prototype with ingress shaping off.

these were taken on a "normal" comcast line of 20Mbit down, 2Mbit up.

2_20mbit_comcast/irene_speedboost_unshaped.ps # "normal" behavior
2_20mbit_comcast/irene_cake_ingress_egress.ps # simple_qos.sh shaper in cerowrt
2_20mbit_comcast/irene_cake_no_ingress.ps # ingress limiting turned
off, egress left on

I also spent some time looking at the behavior of dropbox and netflix.
(no graphs attached)

Both mark their traffic CS1. I knew dropbox did, didn't know netflix did!

How dropbox responds to congestion is interesting. It's pretty good at
not doing bad things to the network. Is there a paper on how it works
somewhere?

netflix does the classic video trick of loading up a giant burst every
few seconds, then going quiescent.


-- 
Dave Täht

Fixing bufferbloat with cerowrt: http://www.teklibre.com/cerowrt/subscribe.html
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