CURRENT_MEETING_REPORT_

Reported by Tony Ballardie/University College London

Minutes of the Inter-Domain Multicast Routing Working Group (IDMR)


Tuesday Session

A summary of the changes to the latest release of ``mrouted'' (DVMRP)
was presented by Steve Deering.  Amongst the many new features, a new
version of IGMP will accompany the new release as a separate module,
allowing for its optional testing.  Details of mrouted's new features
will be announced when it is officially released.

Dino Farinacci presented various changes to PIM Dense Mode (DM). The
main change was to LAN assert messages, the problem being on a
multi-access LAN that non-optimal paths could be chosen.  The solution
involves carrying mertics in ``assert'' messages.

Dino also gave an update on implementation and deployment status.
Cisco's CBONE has 20+ routers running PIM DM and SM at present.

Dino also described PIM's rendez-vous point (RP) reporting mechanism,
which is implemented in the form of a new IGMP message type.  An IGMP
RP-Report message is sent in response to standard IGMP host membership
queries.

Dino's slides are retrievable via anonymous FTP from:


             cs.ucl.ac.uk:darpa/fdm-slides.ps, rp-report.psg


Van Jacobson gave a presentation on ``administratively scoped IP
multicast,'' which involves the designation (by the IANA) of a region of
the multicast address space for use within configurable boundaries.
These boundary configurations would be placed in the configuration files
of multicast routing protocols, such as DVMRP. The primary purposes of
administrative scoping are:  address re-use and prevention of multicast
traffic flow in either direction across a boundary, if that traffic is
destined to a group specified within the boundary range.

Van's slides on administrative scoping are available via anonymous FTP
from:


               cs.ucl.ac.uk:darpa/van-adminscope-slides.ps


Keith McCloghrie presented a summary of three new multicast MIBs:  an
IGMP MIB, a generic multicast routing MIB, and a PIM MIB. An
Internet-Draft on each of these is available from the Internet-Draft
directories as:


   o draft-ietf-idmr-igmp-mib-00.txt
   o draft-ietf-idmr-multicast-routmib-00.txt
   o draft-ietf-idmr-pim-mib-00.txt


Van Jacobson also presented a proposal for multicast traceroute.  This
would be extremely beneficial for the purpose of fault diagnosis on a
multicast path.  A detailed description of multicast traceroute was
given, together with the problems involved in making it work correctly,
despite problems in the network.

Van's traceroute slides are available via anonymous FTP from:


               cs.ucl.ac.uk:darpa/van-traceroute-slides.ps



Wednesday Session


Deborah Estrin presented various aspects of PIM's Dense Mode/Sparse Mode
interaction.  DM and SM were clearly defined as follows:


   o DM stores prune state for active sources
   o SM stores join state for explicit receivers


The slides from Deborah's talk can be retrieved from:


                  cs.ucl.ac.uk:darpa/dm-sm-interact.ps


Van Jacobson presented some notes on multicast scaling and PIM. The
discussion focussed primarily on the state requirement in routers and
link bandwidth requirement on inter-domain (backbone) links, given the
interaction between PIM DM operating within domains, and PIM SM
operating at the inter-domain level.

Scaling statistics were analysed, and various intuitive conclusions
drawn regarding the scalability of PIM operating over the wide-area.

Van's slides for this talk can be found in:


              cs.ucl.ac.uk:darpa/van-pim-scaling-slides.ps


Due to schedule overrun, the interoperability issues of PIM and CBT were
not discussed.  It was decided to follow up this discussion over the
MBone at a time that will be announced on the IDMR list.