Subject: [Diffserv] Report on DECIDES BOF 2

From: Jon Crowcroft <[email-masked]>
Date: Mon, 15 Nov 1999 13:49:40 +0000

Report on DECIDES BOF 2
                                       
   This was a followup to the BOF held in Oslo at the 4th IETF. There' we
   had a consensus that we needed another BOF, but not one for a working
   group (yet). The purpose of this BOF was to allow work since then to
   be presented, and to then see if there were grounds for pursuing a
   working group, or else providing input to existing (or other proposed)
   working groups.
   
   The talks are available through links below.
   
   The outcome of the meeting was that we did not need a new BOF, nor did
   we need a working group. However, it was felt that:
   
     The community needs to continue to refine the traffic source models
   and information about traffic matrices (e.g. for the TE wg) so that
   simulations and analytical work are kept realistic and relevant to the
   IETF.
   
     We do need a path for measurement results to be reported to the
   various relvant IETF working groups. IPPM and Diff-serv and others
   need to liase w.r.t this.
   
     It is possible that soon, but not quite yet, an industrial forum for
   deploying class and quality of services may be needed -the IESG might
   consider a directorate perhaps sometime in the next year.
   
     There is a propsoed IRTF research group that can help with the first
   of these tasks to some extent. We expect new WGs to deal with more
   interim matters, such as composing edge-to-edge services from PHBs.
   Contact
[email-masked]

   for information on that activity - if it comes about, look at the IRTF
   web page for details.
   
The Slides are avaialble from
http://www.cs.ucl.ac.uk/research/decides/report2.html

The Agenda was as follows:

Draft agenda for 2nd DECIDeS BOF, 46th IETF 

BOF Deployment Considerations of Implementing Differentiated Services (DeCIDeS)

60 Minutes.  14.15-15.15, Tuesday November 9, Empire, Omi Shoreham, DC

Problem Re-Statement and News (see the Document) - 		5 mins
	Jon Crowcroft 
	[email-masked]

Measurement
	Terena/TF-TANT Report Tiziana Ferrari <[email-masked]>
	(see www.cnaf.infn.it/~ferrari/tfng/ds-test.html) 	10 mins

	Snelnet ADSL diff-serv trial measurements
	"Wentink, M.M." <[email-masked]> 

	How does signaling based traffic conditioning scale?	5 mins
	[email-masked], Telia Research - 5 mins

Simulation 
	TCP Diff Serve Results					5 mins
	A.L.Narasimha Reddy   "A.L.Narasimha Reddy" <[email-masked]>

	Traffic Engineering for IP Networks with Real-Time Traffic - 5 mins
	Prehofer Christian <[email-masked]>

	Simple scheme for admision control together with simulation  5 mins
		results for real-time traffic.  
	Lars Westberg, Ericsson Research       
	[email-masked], [email-masked]

Operations

	Provisioning for multicast traffic in a diffserv network 5 mins
	Cheng-Yin Lee <[email-masked]>

	 Title : "Diff-Serve and Bandwidth Broker Implementation 5 mins
          in JB Project"
	   Speaker : Hiroshi Esaki (WIDE Project)
	   Works : Univ.of Tokyo, UCLA, Osaka Univ., Keio Univ., NAIST,
           Hitachi, Fujitsu, Toshiba,  etc.,

Where does this work go next in the IETF?			5 mins
	J Crowcroft et al 

	1/ OAM WG to define protocols/procedures for diff serve deployment 
		e.g. like mboned, define tools for debugging (dtrace,
		dpathchar, etc)
	2/ TA WG to explore inter-domain exchange of diff serve capability
		e.g. look at bandwidth broker and survey family of
		protocols for brokering  - rsvp, snmp, rap/aaa, etc

 --------------------------------------------------->
 
BOF Deployment Considerations of Implementing Differentiated Services (DeCIDeS)

Motivation.

The IETF WG on Differentiated Services (diff-serv) has been meeting now for 
over a year now and has made excellent progress. The framework, architecture, 
DS Field definition, and format for traffic conditoners document, and most
importantly , two PHB definitions have been specified.

So what is the problem?

The Integrated Services WG (int-serv) (with its related groups such as 
ISSLL and RSVP and others), has also defined a set of protocols and 
mechanisms for enhanced services in the Internet. The difference between the 
int-serv and diff-serv approaches is that int-serv (at least the Guaranteed 
and Controlled Load services) is amenable to analysis. Effective bandwidth 
calcualations, and the thesis by Parekh shows how the admission tests for leaky
bucket characterised traffic and delay bound for the path can be
calculated. The difficulty with IS has been in designing
implementations that scale (hence a great deal of work in state
aggregation in RSVP, and in fast generalized port specification
classifiers, as well as  the work on efficient queue data structures
and insert/retrieve algorithms, such as WF2Q and approximations such
as SFQ). Indeed, there are network QoS calculi (by Rene Cruz and also
by Jean-Yves le Boudec).

Meanwhile, with diff-serv, the difference is that there can be no
obvious analytic theory of diff-serv. A path can be constructed out of
a sequence of hops each with a PHB and some associated SLA. However,
the service (and provisioning of service) necessarily depend on the
actual network topology and traffic conditions that prevail.

This is a positive aspect of diff-serv, since it gives providers (and
router vendors) a lot of design freedom in how they deploy actual
services (and associated tarrif structures).

However, to evaluate a diff-serv PHB is now a complex task, and
requires simulation or measurement. To date, only modest simulations
and measurements have been carried out.

[Aside: of course the exact same argument
applies to figuring out call blocking
probabilities in int-serv type networks]

Objectives.

To prepare a document that outlines evaluation framework for PHBs by
suggesting realistic topologies and traffic patterns for measurement
or simulation work. Note that there is a health warning associated
with simualtion - see reference [2] below.

Reading

0/ http://www.cs.ucl.ac.uk/research/decides/
Notes and most slides from previous BOF

1/ http://www.cs.columbia.edu/~hgs/internet/traffic.html

2/ Paxson, V., and Floyd, S., Why We Don't Know How To Simulate The
Internet, Proceedings of the 1997 Winter Simulation Conference,
December 1997. at
http://www.aciri.org/floyd/papers/wsc97.ps

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