Diffserv service classes


Less-than-best effort traffic as implemented via the Internet2 Scavenger
Service (see: http://qbone.internet2.edu/qbss/ ) never really took off;
for example, see http://netflow.internet2.edu/weekly/20041108/#dscp
which notes that Scavenger Service (DSCP=8) tagged traffic makes up less
than 1% of all octets and less than 1% of all packets.

One can argue chicken-and-egg (e.g., had it been supported on the commodity
Internet, it would have been more successful), but I think the bottom line
reality was that because

-- Internet2 was/is uncongested, and because
-- the typical university user of I2 pays $0/Mbps used anyhow,

the motivation for users to tag traffic as Scavenger was typically
non-existent (offering a "discount" from a price of zero is hard unless
the model would involve PAYING people who generate less-than-best-effort
traffic, a model which strikes me as, well, somewhat
unsustainable/politically difficult).

A network administrator at a site might unilaterally tag all traffic of a
particular type as less-than-best-effort, but again, unless there is
congestion, that tagging would be to no effect.


Joe St Sauver (joe@oregon.uoregon.edu)
University of Oregon Computing Center

No doubt what you say is true, however, the typical
eVLBI site is not part of the Internet2 (and also
doesn't need the TCP aspects of the Scavenger service).

There are certainly applications and users out there that would
like to use all of the bandwidth possible, but do not need
to step on other, more bit sensitive, services.