Subject: Congestion control

From: Dave Crocker <[email-masked]>
Date: Thu, 14 Dec 2000 14:36:18 -0800

For an industry that has been predicated on queuing theory that permits 
managing data traffic through moments of transient congestion, the idea 
that the best way to achieve Quality of Service is simply to throw excess 
bandwidth at the problem is quaint.

On the other hand, that simplistic congestion control approach has some 
appeal for planning IETF meeting capacity.

Rather than trying to carefully provide "enough" meeting room capacity for 
expected attendance, what would be the effect of reserving *too much* 
capacity for our meetings?

For example, ensure that rooms are 50% larger than we think they need to be 
and make sure there are some extra rooms, in case we need to move an 
oversubscribed group to a larger room.

The only two effects I can think of are:  extra dollars and further 
restrictions on where we can meet.  The latter is inevitable given our 
growth, the planning trick would merely accelerate the constraint.

How bad would the extra cost be?  Given the work we do in these meetings 
and the negative effect of overcrowding, is the extra cost worthwhile?

d/

=-=-=-=-=
Dave Crocker  <[email-masked]>
Brandenburg Consulting  <www.brandenburg.com>
Tel: +1.408.246.8253,  Fax: +1.408.273.6464

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From: "Scott Brim" <[email-masked]>
Date: Thu, 14 Dec 2000 15:58:19 -0800

Given that the overcrowding at this IETF was the worst ever, and really
interfered with work, not to mention the social event ...

Building on a previous suggestion:

* When you register for the IETF, you specify which WGs you are
  interested in in priority order.

* Simultaneously WG Chairs submit lists of people who are active.  This
  includes chairs for new WGs and BOFs.

* The agenda and room assignments coalesce based in part on expected
  attendance -- this probably continues to require hand-crafting.

* Software magically takes registrant WG preferences and fills rooms,
  giving priority to those who have been active (purely according to WG
  chairs).  Once a room is full no one is added.  OK, this is the
  cruddiest part, but leave the details for now.

* People receive mail saying which WGs they have been granted access to.
  They can apply for more, but they probably won't get in, which means
  there is a strong incentive to have specific reasons why they want to
  go to the IETF when they register in the first place.

* When they come to the IETF their packets contain not only a receipt
  (the point being that the packets are already individualized) but an
  authenticated (anything, a little ink stamp, even) schedule, which
  they have to show at the meeting room door to get in the room.

* "Standby" entry is allowed if there are seats not taken 5 minutes
  before the meeting starts.

Details can be explored based on what you think of this in principle.

...Scott

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From: Jelena Mirkovic <[email-masked]>
Date: Thu, 14 Dec 2000 16:57:08 -0800 (PST)

>  cruddiest part, but leave the details for now.
Errrr....so some people get cut off even during registration process???
What does it mean active? How about newcomers?
Would it not be a nice idea to simply find a hotel with enough number
of big rooms so that everyone who wants can fit in? At least at
registration time? And then you can have stand-by for people that did not
register but suddenly decided they would like to attend some sessions.

Jelena

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From: Kurt Erik Lindqvist <[email-masked]>
Date: Fri, 15 Dec 2000 01:27:38 +0100 (CET)

I think this is a really, really, really bad idea. This is my first IETF.
I had read all the drafts of what interested me before going here. I
thought that was enough. Boy was I wrong. I am now also subscribed to the
mailiglists...

However, I have been to several of the other gatherings of the same people
(mostly RIPE) and I thought I was somewhat prepeared for what this woudl
be like. I wasn't. This was unlike anything I have seen so far. I have
learnt alot and I have really enjoyed following the discussions and
meeting the people. 

This was my first IETF but hopefully not the last. I
have learnt some of how the IETF works. I will be following the
mailinglist discussions, and maybe I can contribute something. Maybe I
oneday in the future can contribute something at a meeting. I hope so.

I don't think that this "awakening" should be limited to people that have
been active on mailinglists. It's not the same thing, and it will "scare"
people off. I really hope that instead the logistical problems can be
overcome.

- kurtis -

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From: "Scott Brim" <[email-masked]>
Date: Thu, 14 Dec 2000 17:01:20 -0800

(Continuing this for its value in exploring the issues ...)

> What does it mean active? How about newcomers?

How about newcomers?  IETF activity takes place primarily on mailing
lists.  IETF meetings are to resolve issues and reach closure.  If
you're not active, why are you coming?

> register but suddenly decided they would like to attend some sessions.

Yes of course.  Our capacity needs are going beyond the capability of
most meeting sites.

...Scott

---

From: Kurt Erik Lindqvist <[email-masked]>
Date: Fri, 15 Dec 2000 01:47:50 +0100 (CET)

- kurtis -

---

From: Dave Crocker <[email-masked]>
Date: Thu, 14 Dec 2000 17:31:19 -0800

>Building on a previous suggestion:

Just to be clear, my suggestion is diametrically opposed to the list that 
you specified.

You are suggesting very tight queue management.  By the mid-70's, Kleinrock 
showed that these mechanisms do not work in the face of sustained 
overload.  They only work when the problem is transient.

Rather than trying to manage the congestion, I am suggesting that we throw 
money at the problem, to overbuy space so that we don't have the problem.

d/

=-=-=-=-=

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From: Maurizio Codogno <[email-masked]>
Date: Fri, 15 Dec 2000 02:36:48 +0100

> capacity for our meetings?

there are other solutions, of course. Besides an "admission examination"
for attendants, "right" choice of the venue may cut attendance. Think at
how many people would have come to Minneapolis in December. (On the
downside, those people would have not gone outside the hotel, so congestion
could have been even worse)

My personal experience shows that BOFs are the most overcrowded meetings: I
don't know whether this is the result of a biased estimation (nobody knows
in advance who will participate to a BOF, since there is no official
group), but I also believe that people stay there just to see what happens,
and this is much easier than to attend a regular WG meeting, where people
talk about actual drafts (ok, *some* people talk, but the idea is this
one). Maybe a "preparatory mailing list" one month before the meeting may
help to tell the bona fide participants, and allow to give them a "premium
pass" ...

ciao ,.mau.

---

From: "Scott Brim" <[email-masked]>
Date: Fri, 15 Dec 2000 07:58:12 -0800

> money at the problem, to overbuy space so that we don't have the problem.

So, throwing bandwidth at the problem is quite cost-effective in about
85% of the cases, and congestion control is most useful at aggregation
points, say where enterprise networks meet regional networks.  It would
seem then, that we should solve the meeting room congestion by getting
really big rooms, and control access to the halls?

...Scott

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From: Harald Alvestrand <[email-masked]>
Date: Fri, 15 Dec 2000 08:01:38 -0800

>register but suddenly decided they would like to attend some sessions.

there is a little problem with the timelines of IETF planning...
if you have a BOF meeting at time T, the timeline is roughly:

T-2 years: Contract with hotel is signed
T-3 months: Most participants register
T-2 months: BOF proponents start registering
T-1 month: BOF is announced
T-1 week: BOF agenda is posted
T-3 days: Last BOF participants decide to attend the IETF
T-5 minutes: Lots of IETF participants decide to attend the BOF
T: BOF happens
T+5 minutes: Complaints about room crowding hit the IETF list :-)

If someone wants changes to earlier decisions based on events that happen 
later, please send one (1) time machine to the IETF secretariat.

(guessing is what we already do!)

--
Harald Tveit Alvestrand, [email-masked]
+47 41 44 29 94
Personal email: [email-masked]

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From: Fred Baker <[email-masked]>
Date: Fri, 15 Dec 2000 12:26:13 -0800

>really big rooms, and control access to the halls?

It is possible to avoid congestion entirely. Use beaches. There may be 
other problems :^)

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From: Fred Baker <[email-masked]>
Date: Fri, 15 Dec 2000 12:24:25 -0800

At 04:57 PM 12/14/00 -0800, Jelena Mirkovic wrote:
>of big rooms so that everyone who wants can fit in?

I don't know if you are aware of it, but there is a very simple algorithm 
for determining what the "conference hotel" will be for any given meeting. 
Ask what city it is in, and find out what the largest hotel is.

We are already going to the largest places we can find short of going to 
conference centers; in some cases, we are already using conference centers. 
I have asked the Secretariat to advise me, quantitatively, of the 
implications of making that leap. I can tell you up front that it has 
implications for either the meeting fee or the corporate sponsorship.

---

From: "Henning G. Schulzrinne" <[email-masked]>
Date: Fri, 15 Dec 2000 19:59:10 -0500

In case the IETF is truly desperate: We could also rent out a major
university during the summer and stick everybody in dorm rooms - that
should be enough to discourage the tourists and evoke the roots of the
Internet :-) I'm sure OSU has classroom space for a few ten thousand
students... 

Then, there's always the Scout Jamboree option: build an Internet tent
city. I'd imagine Burning Man has more attendees than the IETF and it
seems to draw some of the same crowd.
-- 
Henning Schulzrinne   http://www.cs.columbia.edu/~hgs

---

From: John Collis <[email-masked]>
Date: 15 Dec 2000 17:06:57 -0800

Fred Baker <[email-masked]> writes:
> I don't know if you are aware of it, but there is a very simple
> algorithm for determining what the "conference hotel" will be for any
> given meeting. Ask what city it is in, and find out what the largest
> hotel is.
> 
> 
> conference centers; in some cases, we are already using conference
> centers. I have asked the Secretariat to advise me, quantitatively, of
> the implications of making that leap. I can tell you up front that it
> has implications for either the meeting fee or the corporate
> sponsorship.
> 

IMO that is becoming obvious and although some people will hate the idea,
I think the latter option is probably the only realistic one. We still
need to make it reasonably easy enough for anyone to attend. Therefore we
can't afford to blowout the cost of coming to an IETF so that only those
individuals working for companies with deep enough pockets can attend.

Cheers,
-- 
John Collis
IndraNet Technologies Ltd.
Email: [email-masked]

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From: Grenville Armitage <[email-masked]>
Date: Fri, 15 Dec 2000 17:47:01 -0800

"Henning G. Schulzrinne" wrote:
> Internet :-)

Many a true word is said in jest....

cheers,
gja

---

From: Dave Crocker <[email-masked]>
Date: Fri, 15 Dec 2000 18:42:16 -0800

>implications for either the meeting fee or the corporate sponsorship.

And that impact is precisely why I phrased my suggestion as a question.

On the other hand, we are growing, so that impact will be felt at some 
point, no matter what.  The congestion problem hits us regularly, so it 
seems worth looking for some sort of basic change to eliminate it.

I do not believe that better "planning" is really feasible; too many 
variables the planners cannot predict or control.  I also do not believe 
that restricted attendance or other draconian administrative practises are 
appropriate; they would dramatically alter the nature and dynamic of our 
communal get togethers.

More space is entirely practical, except for the open question of cost.

But since growth ensures we encounter the problem eventually, let's gain 
the upside from it sooner rather than later.

d/
=-=-=-=-=

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From: Tripp Lilley <[email-masked]>
Date: Sat, 16 Dec 2000 10:53:56 +0000 (/etc/localtime)

> seems to draw some of the same crowd.

Interop tried this at Vegas shows from, what, '96 through '98, when they
outgrew the LVCC :) Marketing called it the HTFE -- "High Tension Fabric
Enclosure", but the NOC team preferred "Temporary Enclosure Needing
Tension" -- TENT.

-- 
   Joy-Loving * Tripp Lilley  *  http://stargate.eheart.sg505.net/~tlilley/
------------------------------------------------------------------------------
   "There were other lonely singers / in a world turned deaf and blind
    Who were crucified for what they tried to show.
    Their voices have been scattered by the swirling winds of time,
    'Cause the truth remains that no one wants to know."

   - Kris Kristofferson, "To Beat the Devil"

---

From: Paul Hoffman / IMC <[email-masked]>
Date: Sun, 17 Dec 2000 11:25:10 -0800

WG chair says "OK, the room is now over-full. Who are there people in 
the doorway or outside who intend to work actively on drafts or 
forming the charter for this group? I see seven hands up. Could 
fourteen people who are currently sitting or jammed up against a wall 
who do *not* already plan to work actively on drafts or forming the 
charter for this group please be polite and leave? I will announce 
the mailing list address for this BOF on [email-masked] if we get 
anywhere during this hour. Also, look for an announcement of a Bar 
BOF on the messages board later today. OK, about ten people have 
left. Thanks!"

This, of course, relies on the early sitters being polite and 
patient, but that has been known to happen at various times in IETF 
history.

--Paul Hoffman, Director
--Internet Mail Consortium

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From: Dave Crocker <[email-masked]>
Date: Mon, 18 Dec 2000 08:55:27 -0800

At 11:25 AM 12/17/00 -0800, Paul Hoffman / IMC wrote:
>WG chair says "OK, the room is now over-full. Who are there people in the 
>doorway or outside who intend to work actively on drafts or forming the 
>charter for this group? I see seven hands up. Could fourteen people who 
>are currently sitting or jammed up against a wall who do *not* already 
>plan to work actively on drafts

This is among the set of reasonable procedures to follow when there is 
congestion.  As with each technique suggested, there are benefits and there 
are problems.

However the premise to my suggestion is that we are growing and are going 
acquire larger venues eventually.

So let's acquire them a little sooner and avoid the pain of congestion and 
imperfections and inconveniences of all these congestion management techniques.

d/

ps. The plea for less active attendees to move works once.  It does not 
cover late arrivals.  Taking a Draconian attitude towards active 
participants who arrive late is an example of the imperfection of the 
management techique.

=-=-=-=-=

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From: Bob Hinden <[email-masked]>
Date: Mon, 18 Dec 2000 10:20:59 -0800

I find it amusing that this debate on how to handle "congestion" at IETF 
meetings mirrors the technical debate on congestion in the Internet.  The 
two sides still seem to be "more bandwidth" or "apply QOS".

Bob

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From: Grenville Armitage <[email-masked]>
Date: Mon, 18 Dec 2000 17:31:40 -0800

wait for the Assured Seating (AS) Per Hotel Behavior (PHB) with
multiple drop precedence levels.... badges are marked on ingress
to the room based on willingness to work... the chair drops people
marked "dead weight" first as the room fills.... in order to come
up with another diffserv-related acronym, sophisticated chairs use
reverse RED (Read Every Draft) to boot out those who havent.

cheers,
gja

-- 
________________________________________________________________________
Grenville Armitage                    http://members.home.net/garmitage/
Bell Labs Research Silicon Valley

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From: Fred Baker <[email-masked]>
Date: Mon, 18 Dec 2000 17:55:02 -0800

>two sides still seem to be "more bandwidth" or "apply QOS".

Actually, there are three avenues under discussion. "More bandwidth", and 
"ensuring access for the critical participants" are the ones you mentioned. 
The third is "apply random early detection with sufficient force to ensure 
that the meeting fits in the room."

Reality, IMHO, involves some elements of each of the above. Our experience 
has been that we do indeed get the largest venues we can consistent with 
the projected attendance, and we do in fact ask people to let the folks who 
have read and posted drafts get in the room. BOFs are often decided weeks 
in advance, while venues must be contracted months to years in advance, and 
people decide what to attend as little as minutes before entering the room. 
I get impatient with the summary dismissal of people as "tourists", but in 
point of fact when I have ten contributors in a room that will hold 100 and 
I have another hundred telling me that "the conference attendance is 2700, 
divide by 8 and make sure that every room will hold that number of people", 
I do begin to wonder whether every single one of those people is in fact 
critical to conducting the meeting.