[e2e] queuing/dropping algorithms *actually* deployed

John Kristoff jtk at northwestern.edu
Thu Jun 22 14:38:00 PDT 2006

On Wed, 21 Jun 2006 17:18:07 -0400 (EDT)
mbgreen at dsl.cis.upenn.edu wrote:

> I realized that I had no idea what to tell him.  In what
> fraction of routers is RED turned on and used these days?  Is some

This came up in a a thread entitled "Is Red Dead?" on this last year
in September and October.  Perusing those posts will give you some

> sort of fairness or QoS preserved in a measurable fraction of routers?
> Scheduling?  10 or 15 years ago I guess I could have safely said
> queues are almost all FIFO and drop-tail controls when packets are
> dropped and basically nothing else is relevant in a formal model.

This is probably still true, but I know there has been some use of
QoS/AQM within organizations turning that stuff on as they deploy
VoIP.  Though in my experience, except for those limited WAN links
most of preferential treatment of packets and dropping is not
actively happening.  Furthermore, in my experience, monitoring to
see if those knobs are doing something useful is rarely being done.

Recently I have heard of one very large content provider who is
deploying "QoS".  As it was described to me, it was mainly as a means
to help decide "who/what" gets to live if a significant portion of
the network goes away rather than as a way to prioritize packets in
normal operation.  I'm not sure if this is public knowledge, but I
am hoping they'll at least do some kind of talk based on their
experience soon.

All the political talk of net neutrality I suppose may spur some
additional management pressure to do "QoS" as well.


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