[e2e] queuing/dropping algorithms *actually* deployed

mbgreen@dsl.cis.upenn.edu mbgreen at dsl.cis.upenn.edu
Thu Jun 22 06:29:32 PDT 2006

[I guess I need to fix my "From:" address; the first time I sent
this it was rejected.]

   From: David P. Reed [mailto:dpreed at reed.com]
   Sent: Thursday, June 22, 2006 4:10 AM
   What is the scope?   Are you interested in the  
   queueing/dropping protocols deployed on gateways
   connected via carrier pigeons according to the RFC 

I guess that's a good question and I should clarify.  By
algorithms "deployed in routers in the Internet" I meant
queuing/dropping algorithms deployed in a measurable
fraction of routers reachable through IP, by packets with
IPv4 or IPv6 Internet addresses from a source attached to
the "public" Internet (e.g. the "Internet" accessible from
an ISP such as Comcast or Verizon or by being connected
through most U.S. universities).  

As to your particular example: if a significant fraction
of such routers were connected by carrier pigeons, then
yes, I'd want to know about that.  If these were common
enough then I'd bet there would be models of the likely
order in which packets would arrive, and the odds of them
being dropped (Maybe not even so complicated a model if
pigeons in Trafalgar square use "tail"-drop, no? :-)
Similarly, if there happen to be a lot of gateways
connected by men with telescopes and flags or sending
morse code, then I'd want to know about.

But I thought that pigeons, and telescopes, and smoke and
mirrors were rare (relatively) these days --- at least
from routers reachable by standard IP addresses from the
"Internet".  But I don't *know* that, because I don't know
what is commonly deployed today, nor what algorithms are
commonly provided or actually turned on in the
routers/gateways that *are* deployed.

Thanks for any info.
   If so, I am prepared to send samples of the droppings,
   at least, from
   Trafalgar Sq.
   mbgreen at dsl.cis.upenn.edu wrote:
   > A colleague who wanted to do some formal model checking and
   > formal performance analysis on an application-level protocol
   > going through a router, asked me what algorithms are used in
   > currently deployed routers in the Internet.  (Looking for an
   > accurate model of packet drops when this protocol was
   > running alongside many flows of the same protocol, as well
   > as both congestion aware *and* inelastic bad-behaving
   > flows).
   > 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 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.
   > Today I have no idea.  Is there some web site somewhere that
   > can give me this information?  Is e2e the right place to ask
   > this question --- if not, then where? [and, in that case, my
   > apologies for sending it here]
   > Thanks in advance for any pointers.

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