CURRENT_MEETING_REPORT_
Reported by Dave Katz/cisco Systems
Minutes of the IS-IS for IP Internets Working Group (ISIS)
CLNP Multicast
Radia Perlman gave a presentation on several methods of achieving CLNP
multicast functionality without significantly changing unicast routing.
One use of multicast is for service location. This could be achieved in
CLNP by using a well-known system ID for each service and advertising it
via unicast routing (from multiple locations). This is also known as
``anycast.''
In the very branchy case, one could use NSAP addresses with the
multicast bit set in the system ID. Then a single spanning tree per area
could be created for all multicast destinations and data packets could
be delivered to all subnetworks in the area along this spanning tree.
Since it is very branchy, no pruning mechanisms are necessary (making it
simple). Inter-area forwarding could be accomplished by simply sending
one packet per destination area (normal unicast routing would take place
until the packet arrives in its destination area), or by creating a
special area address that means ``all areas,'' calculating a single
spanning tree over all areas, and delivering the packet to the entire
domain.
For very sparse multicast with a limited number of participants per
group, a scheme such as CBT would be appropriate. One suggested
optimization was to tunnel data packets between the routers at the
branching points; this eliminates the need to set up state through the
non-branching routers.
IS-IS Over Non-Broadcast Multiaccess (NBMA) Networks
An Internet-Draft has been published on IS-IS over non-broadcast
multiaccess (NBMA) networks; the Routing Over Large Clouds Working Group
(ROLC) was due to take up the subject during this IETF meeting.
The Integrated IS-IS Specification
The latest version of the Integrated IS-IS specification Internet-Draft
(the changes to which were essentially reference updates) has expired.
The protocol cannot continue along the standards track until RFCs
describing operational experience and an analysis of the protocol are
published. Chris Gunner is working on those documents.
Integrated IS-IS for IPX and Appletalk
The ISIS Working Group charter needs to be revisited in order that it be
broadened to include other topics, such as Integrated IS-IS for IPX and
Appletalk.
Radia gave a presentation on Integrated IS-IS for IPX and Appletalk.
The significant issues include encapsulation (in order to carry data
packets through islands that do not provide native forwarding service
for the protocol), metric translation, route propagation between areas
(and between protocols), clustering issues for protocols with small
address spaces (such as the creation of addressing domains for
Appletalk), the use of tunnels to carry routing information between
areas when the level 2 subdomain does not understand the protocol, and
various issues specific to the protocols (zones, services, etc.). An
Internet-Draft has been published on the subject.
Radia described the new Novell link state protocol for routing IPX,
Netware Link Services Protocol (NLSP). NLSP is basically equivalent to
IS-IS, and uses compatible packet formats. There are several minor
improvements, most of which could be realized in IS-IS without actually
changing the protocol definition. There are also several changes deemed
necessary for using the protocol in an IPX environment such as the
inclusion of service advertisements, and running the protocol over IPX
rather than over the data link (though it was observed by some present
that this is unnecessary). Several people expressed the view that it
would be possible to implement IS-IS and NLSP from a single code base
without too much difficulty.
IS-IS Enhancements
Discussion turned to enhancements and changes that the group might like
to pursue with IS-IS.
o Increasing the LSP number space to four octets (allowing vast
amounts of information to be carried, such as large numbers of BGP
routes, and also allowing implementations to use OSPF-style
numbering of individual adjacencies)
o Designated router ``tenure'' (increasing the DR election priority
after being elected DR in order to provide stability for the choice
of DR--no protocol change necessary)
o Allow different LSP holding time values per LSP (so that static
information such as service advertisements can be advertised less
often)
o Possible fixes to the ``hedgehog'' problem (extremely branchy,
low-speed networks). Ross Callon will write this up
o Expand the pseudonode ID to two octets (in order to support more
than 255 circuits per router)
o Multilevel (>2) routers
o Multiarea routers (no protocol change necessary)
o Integrated IPX/Appletalkrouting
o NBMA support
o Further definition of the External Info attribute
o Multicast routing
o Increase the size of link metrics from 6 to 16 bits, and total path
cost from 12 to 32 bits
Dave Katz agreed to write up a draft for increasing the LSP number,
pseudonode ID, and link metric fields, as well as a proposal for how to
transition to new versions of the various packets (necessary because the
changes are incompatible with the existing packet formats).
Attendees
Kenneth Albanese albanese@icp.net
William Barns barns@gateway.mitre.org
Ross Callon rcallon@wellfleet.com
Chris Gunner gunner@dsmail.lkg.dec.com
Herluf Hansen hha@tbit.dk
Susan Hares skh@merit.edu
Marc Hasson marc@mentat.com
Denise Heagerty denise@dxcoms.cern.ch
Cornelius Healy con@icp.net
Robert Hinden hinden@eng.sun.com
Phil Irey pirey@relay.nswc.navy.mil
Matthew Jonson jonson@ddn.af.mil
Akira Kato kato@wide.ad.jp
Dave Katz dkatz@cisco.com
Tony Li tli@cisco.com
David Marlow dmarlow@relay.nswc.navy.mil
Randy Miyazaki randy@lantron.com
Doug Montgomery dougm@osi.ncsl.nist.gov
Dennis Morris morris@altair.disa.mil
Ismat Pasha ipasha@icm1.icp.net
Alex Reijnierse a.a.l.reijnierse@research.ptt.nl
Allen Rochkind Allen_Rochkind@3com.com
Greg Ruth gruth@gte.com
Dallas Scott scott@fluky.mitre.org
Frank Solensky solensky@ftp.com
Thuan Tran thuan@xylogics.com
Scott Williamson scottw@nic.ddn.mil
Jean Yao yao@cup.hp.com