CURRENT MEETING REPORT


Reported by Howard Berkowitz, PSC International and Andrew Malis, 
Ascom Nexion, Inc.

Minutes of the Routing Over Large Clouds Working Group (ROLC)


The ROLC Working Group met in two sessions at this IETF.  There were
approximately 145 attendees.

Agenda:

o  First Session
o  Agenda bashing
o  ATM Forum MPOA update
o  Joint statement by the IPATM and ROLC chairs
o  NHRP specification and open issues--draft-ietf-rolc-nhrp-06.txt

o  Second Session
o  ATM Forum Liaison
o  Local/Remote Forwarding Decision--draft-ietf-rolc-apr-03.txt
o  Mobile NHRP Devices--draft-horikawa-mobile-nhrp-00.txt
o  ATMARP/NHRP Translation
o  Router-Router NHRP
o  Status and Workplan


SESSION ONE


ATM Forum MPOA Update

George Swallow, the ATM Forum Multi-Protocol Over ATM (MPOA) 
Sub-Working Group Chair, reported that the MPOA current approach 
is  based upon NHRP and MARS.  No protocol design is being done; 
NHRP  "out-of-the-box" is desired.  The MPOA SWG appreciates the 
work  being done in the IETF to harmonize NHRP and MARS.  There is 
very little interest in the ATM Forum in RFC 1577 (Classical IP over 
ATM).  ATM Forum LAN Emulation (LANE) is used at layer 2.  Both 
"edge devices" and routers are supported by MPOA.  Server redundancy  
is a major concern.  MPOA has additional concerns, such as edge device-
to-edge-device connectivity.  The external ATM Forum MPOA and 
PNNI mailing lists, as reported at the Stockholm ATM Forum BOF, 
still have not been set up by the ATM Forum.  It is premature for  the 
IETF to be citing ATM Forum UNI 4.0; its public release date is unclear, 
with a current February goal for straw vote.  Forum/ITU politics may 
also delay its completion.  Joint statement by the IPATM and ROLC 
chairs

Mark Laubach (the IPATM chair) and Andy Malis presented a chair's 
statement regarding ROLC and IPATM coordination of the transition 
from ATMARP to ATMARP + NHRP to NHRP.  A mention was made 
that the IESG has stated that a well-defined step-wise transition plan 
that  emphasizes interoperability with the installed base is required 
for any evolution of a widely deployed proposed standard.  All clients  
must be able to resolve the address of any other client by required  
default behavior (for the given client type) regardless of 
implementation or deployment.  In the following discussion, the ROLC  
Working Group asked that references to NHRP be removed from Mark's 
IP/ATM  Classic2 draft, to allow a separate transition plan to be 
developed.


NHRP Specification and Open Issues

The working group next discussed some NHRP open issues from version-
06 and the mailing list.

1.  MARS harmonization-Hardware Type field vs. Address Family  
field:  The motivation for each choice was continued from the  mailing 
list discussion.  Good points were made on either side, after which the 
clear working group consensus was to use Address Family to identify the 
NBMA address type.  Grenville Armitage made the corresponding 
change to the MARS specification to allow continued  NHRP and 
MARS harmonization--see draft-ietf-ipatm-ipmc-10.txt.

2.  MARS harmonization-address field coding and parsing:  NHRP was 
zero-filling addresses to 32-bit boundaries, while MARS was not.  The 
chair noted that it would be nice for them to be same, if only  for code 
reuse in your implementations.  After discussing the relative merits, the 
working group agreed to "align" with MARS and not zero-fill addresses 
to 32-bit boundaries.

3.  Destination prefix vs. mask:  The consensus was to go back to the 
prefix rather than the mask.

4.  Using prefixes with purge messages:  The consensus was to allow 
prefixes with purges.

5.  Purge acks:  The working group discussed whether or not purges 
should be  acknowledged.  The consensus was yes.  It is up to each purge 
sender  to decide whether to wait for the ack and whether or not to 
resend  the purge if the ack doesn't come back, but purge receivers must  
always send acks.  There was little consensus one way or the other  for 
adding a bit to the purge specifying whether or not the receiver  should 
send an ack; this should be further discussed on the list.

6.  MTU:  The suggestion was made to use currently unused header space 
for MTU discovery.  There was clear consensus to add this feature, as it 
is consistent with RFC 1626 requirements.

7.  Server redundancy:  This is not addressed in the current spec.  A strict 
reading suggests that if there is more than one NHS in a LIS, then 
NHRP clients must register with all of them.  The working group 
agreed that addressing server redundancy is required before NHRP is 
"ready for prime time".  The working group agreed that it would be a 
reasonable goal  to leverage the IPATM Working Group's 
synchronization method, if possible.  This discussion will be continued 
on the mailing list.

8.  Autoconfiguration:  The issue of how to configure clients and servers 
came up during the redundancy discussion.  There was strong  consensus 
for autoconfiguration capabilities, supported either from network 
management via the NHRP MIB, or via a configuration server.  The 
view was expressed that while ATM anycasts are useful to find  
configuration servers, they should not be used to find NHRP servers,  but 
the working group did not reach consensus on this point.  There was  
discussion of whether to use NBMA-level configuration services when  
available; this led to a liaison to the ATM Forum regarding ROLC's  
interest in using the ATM Forum's LAN Emulation Configuration Server  
(see below).  The point was also made that ATM Forum anycasts cannot 
be used in an IETF document until UNI 4.0 is publicly available.  The 
autoconfiguration discussion will be continued on the list.

9.  [This was actually discussed in the second session, but logically  fits 
in here.]  The question was asked why clients are configured with their 
server's IP address.  The consensus was that this was  just a holdover 
from server mode, and that it should be removed from  the spec.


SESSION TWO


Joint ROLC/IPATM Liaison to the ATM Forum

The ATM Forum liaison was discussed and amended.  The liaison  
included two sections, one suggesting leveraging the LANE  
configuration server for IETF uses, the second asking for LAN  Emulation 
Configuration Server redundancy.  The liaison was later presented at 
the IPATM Working Group meeting, where it was accepted and  
forwarded to the ATM Forum liaison, Joel Halpern.


Local/Remote Forwarding Decision

Yakov Rehkter presented draft-ietf-rolc-apr-03.txt.  His talk discussed 
issues such as:  Why do we care how the local/remote decision made?  
When can SVCs be used effectively?  When is the overhead of SVC 
setup justified?  Other issues discussed included  connection 
setup/teardown, Quality of Service, and SVC sharing.  He pointed out 
that we should rethink the subnet model, and replace it  with a local 
vs. remote model.  Numerous options then result, significantly larger 
than with the classic LIS model.  If the model is relaxed, can link layer 
connectivity always be reached?  Try to  establish connectivity--if not 
reachable, then fall back to the  routed path.  How should we do 
address assignment in the absence of  the subnet model?  Instead, use the 
notion of "groups."  A group implies assignment of end host and router 
addresses from a single prefix.  Routers in the group advertise routes to 
the prefix.  In discussion, the working group agreed to the term "Local 
Address Group" (LAG)  for this group.  The working group also agreed 
that Yakov will update the draft  based upon the discussion, and there 
will be a subsequent working group last call, followed by submitting the 
draft to be published as an Informational RFC.


Mobile NHRP Devices

Hiroshi Suzuki presented draft-horikawa-mobile-nhrp-00.txt.  He 
began his talk by noting that it is more of a "NHRP Client  
Autoconfiguration" than a "Mobile NHRP" talk, although mobility 
issues were also included.  He stated that autoconfiguration is  required 
to make supporting a large number of clients practical.  He presented 
the client's use of anycast to a "well-known" address to  find any NHRP 
server on the NBMA, not necessarily one in your LIS.  If a server 
receives a registration for a client in a LIS other than  its own, then the 
server forwards the registration to the client's home server along the 
usual routed path (just like forwarding a NHRP  Request).  This 
procedure only works when the client is in the same  NBMA cloud as its 
home LIS.  The working group really liked this registration 
optimization, and agreed to include it in the spec.  To allow secure 
registration, NHRP also needs end-to-end authentication in addition to 
the current hop-by-hop authentication.  The working group agreed that 
in registration packets, encryption would be end-to-end, otherwise hop-
by-hop as before.


ATMARP/NHRP Translation

Rob Coltun presented one viewgraph on his approach to 
ATMARP/NHRP  translation.  His ATMARP and NHRP servers are co-
resident.  If an ATMARP pertaining to the local LIS arrives at the 
server, the ARP code handles it.  If it is beyond the local LIS, the 
ATMARP code translates it into a NHRP request, and forwards it to the 
NHRP code.  The same model is also used for incoming NHRP requests.


Router-Router NHRP

Yakov Rehkter presented his approach to router-router NHRP, based 
upon two messages he sent to the mailing list.  Yakov discussed 
tradeoffs required for cut-through paths, including increased state and 
control traffic, how to determine whether a cut-through path is  still 
valid, how to avoid black holes and routing loops, how to  determine 
when to bring down SVCs, and interactions with BGP and  inter-domain 
routing.  Yakov will be documenting this information in a forthcoming 
draft, which the working group agreed will be the basis for further 
work.


Status and Work Plan

The working group agreed that the charter and work plan need to be 
revised;  this will be done on the list.  The tentative work plan 
discussed in the meeting is:

December 1995		Produce version 07 of the NHRPv1 spec, new 
LAG (was APR) draft.

January 1996			Final calls on these documents, submit 
to IESG

March 1996			Discuss companion documents-NHRPv1 
Applicability Statement, MIB, Protocol Analysis, router-to-router 
(NHRP v2), server-to-server synchronization,transition plan, using 
shortcuts for IP multicasting

June 1996			Discuss 
implementation/interoperability issues, finalize NHRPv1 companion 
documents, further discuss NHRPv2.

December 1996		Complete NHRPv2.


The meeting adjourned following this discussion.

Later in the week, the ROLC and IPATM chairs met with the Routing 
Area Director (Joel Halpern) and the Internet Area Directors (Susan  
Thomson and Frank Kastenholz) to discuss the transition plan and  
direction of the working groups.  The recommendations to the working 
groups from this meeting are that:

The IPATM Classic2 draft should proceed with ATMARP and without 
reference to NHRP, and include ATMARP server synchronization.

The IPATM and ROLC working groups should coordinate MIB 
development, explore leveraging the same server synchronization 
methods, and keep in mind that future IAB/IETF directions may require 
authenticated address registration (i.e., this is a heads up, and don't 
preclude a straightforward evolution to this as part of the 
synchronization
work).

A future ROLC RFC will be used to specify how to substitute NHRP for 
ATMARP; i.e., IPATM will continue to develop ATMARP in its work at 
this time.