Subject: Workplan Proposal: Benchmarking Differentiated Services Mechanism

From: "Perser, Jerry" <[email-masked]>
Date: Fri, 27 Oct 2000 12:00:06 -0700

The Benchmarking Differentiated Services Mechanisms Proposal intends to
address new problems created by differentiated service mechanisms.  These
problems are not evident when testing with RFC2544 or RFC2889.  The main
problems we propose to tackle are:

1. Extending current metrics, which assume the absence of congestion, to
address the issues of DUT behavior during congestion.  Metrics like
Throughput (RFC1242), measure the point just before DS (Differentiated
Services) has to make a decision on who to forward and who to drop.
Throughput is very useful to find out how much a DUT can handle until a DS
kicks in.  The new metrics we propose have the following qualities:
     - Defined as a per hop behavior (PHB).
     - Defined explicitly for congested traffic where the DUT MUST drop
frames.
     - Several PHBs can be combined to approximate a path segment.  There is
no
       intent to represent end-to-end measurements.  Rather, a goal of this
effort
       is to evaluate what effect each DUT's metrics have on, say, a
backbone network
       as a whole. 

2. Defining specific methods to activate the DS in order to get an
"apples-to-apples" comparison.  Different forms of DUT congestion will
produce different results.  Main factors are traffic distribution, amount of
over-subscription, and number of code points used.  On the issue of code
points, a DUT might have 2, 4 or 8 queues to handle all 64 code points.  If
a DUT only has 4 queues, then how does it handle 64 different services?

3. Creating one set of metrics for both IP precedence and DSCPs.  IP
precedence is currently deployed.  DSCP is just starting to be deployed.  By
defining one methodology for both technologies, we help the latest networks
while supporting existing ones.

4. Defining test scenarios for multiple DSCPs.  Most tests today just test 2
priorities: protected and unprotected.  But DSCP can theoretically handle
priorities.  A new model is needed to replace the current binary model.

5. Creating a foundation for new technologies that do a DS-type forwarding
decision not based in the IP header.  These technologies can build upon the
DSCP test methodology.  One such technology is MPLS, where the DSCP
functionally is embedded in a label just before the IP header.

___________________________________________________________ 
Jerry Perser               Phone: 818.676.2320 
SmartLab Manager           Lab:   818.676.2337 
SmartBits Systems          Fax:   818.880.9165     
26750 Agoura Road          Corp:  818.676.2300 
Calabasas, CA, 91302       Pager: [email-masked]