CURRENT MEETING REPORT


Reported by Marshall T. Rose, Dover Beach Consulting, Inc.


Minutes of the SMNP Agent Extensibility Working Group (AGENTX)

The AGENTX Working Group met for two sessions at the 34th IETF.

Session 1

The first session was held on Wednesday, December 6th.  There were no 
changes to the agenda published on November 27.

The Chair began with a presentation (also available in postscript) 
which:

o  reviewed the Working Group's charter;
o  described, in high-level terms, the multiple component problem; and,
o  reviewed previous IETF publications in this area.

There was considerable discussion with respect to the high-level 
description of the multiple component problem.  The resulting comments 
were incorporated into the presentation.

The Chair then called for presentations by interested parties.

Jim West made a presentation describing his experiences with packet-
based multiplexing.  He noted that the use of port 161 is driving the 
need for sub-agents and that independent functional entities are best 
implemented using packet-based multiplexing.  Other points included:

o  the "real" snmp agent is started on a non-standard port;
o  the proxy-agent listens on port 161, and forwards requests to proxy-
   targets based on community name; and,
o  if the community is unknown, the request is forwarded to the original 
   agent.

Limitations to this approach are:

o  there is no "standard" API for component developers; and,
o  moving the "real" snmp agent to another port is problematic in some 
   environments, e.g., if the agent reads a configuration file to 
   determine its port number, then other processes on that system (e.g. 
   management applications) will malfunction if the configuration file 
   is altered; but, if the agent has the port number hard-coded, then its 
   object code must be patched directly.

Bert Wijnen made a presentation describing his experiences with 
variable-based multiplexing.  He noted that too many interfaces for 
component developers is the driving force, and that in developing his 
approach, DPI, he sought to:

o  hide complexity from the component developer;
o  split the core of the agent code from the instrumentation;
o  require no modifications of management applications; and,
o  provide a "drop-in" solution for component developers.

His approach is targeted for developers of non-network related 
components and is documented as RFC 1592.

With only a few minutes left, the Chair asked for other presentations 
to be made in the second session.  In the interim, there was some general 
discussion on whether management applications could support multiple 
community strings when communicating with the same agent.


SESSION 2

The second session was held on Friday, December 8.

The Chair indicated that he was stepping down at the end of this 
meeting, and that Bob Natale would assume the position of Chair.

Jeff Case made a presentation describing his experiences with variable-
based multiplexing.  Jeff noted that the need for implementation 
standard MIB modules is the driving force, and that in developing his 
approach, EMANATE, he sought to:

o  achieve source code portability and binary interoperability;
o  achieve compliance with both the SMI and the protocol (e.g., support 
   multi-phase operators); and,
o  achieve flexibility by utilizing the most efficient communications 
   facilities available on the target platform.

His approach supports environments in which there is interaction 
between multiple MIB modules which may be cooperatively realized 
by multiple implementation units.  In addition, his approach is a 
programmatic rather than a protocol approach, and hence is not openly 
published.

Randy Presuhn made a presentation describing ongoing work in the area 
of variable-based multiplexing.  This work focused on issues of both 
correctness ("as if simultaneous") and performance (optimizing multi-
phase operations).  In addition, he suggested that the key issues were 
to develop:

o  a set of service requirements;
o  a service definition (i.e., an abstract api); and,
o  a specification for the protocol used for intra-agent communication.

Brian O'Keefe made a presentation on behalf of himself, Andy 
Bierman, Baria Greene, and Dave Perkins, in which they suggested 
that the Working Group distinguish between:

o  logical entities, which implement functional components, and contain 
   a system group; and,
o  implementation units, which are realized by sub-agents.

For example, a managed system might contain four logical entities: 
itself, a router, and two bridges.  Further, the two bridge entities might 
be realized by three implementational units, one of which is shared 
between the two logical entities.  Although there needn't be any logical 
structure imposed on how implementation units comprise functional 
components, an important question is whether there is a one-to-one or a 
one-to-many relationship between an operational scope and a logical 
entity.  It was noted that this dichotomy helps to explain the 
difficulties in implementing interMIB relationships.

Prior to leaving, the new Chair presented a few thoughts on the 
AGENTX Working Group.  He stated that he would ask the Area 
Director to appoint a facilitator for the Working Group, to oversee both 
content discussion and process.  He also felt that the Working Group 
should:

o  focus on the solution space;
o  base approved solutions on a developed and published specification;
o  take a "bottom-up" approach towards a solution; and,
o  leverage SNMP whenever possible.

Dan Romanscieu made a presentation describing his experiences with 
variable-based multiplexing.  His approach sought to:

o  minimize the number of managed elements visible to management 
   applications;
o  provide an alternate multiplexing agent in case of failure; and,
o  require only minimal configuration.

He expressed concern over the difficulty of mapping MIB modules onto 
implementational units. And, in view of his experiences, he felt that 
the Working Group's goals were ambitious.

Finally, there was group discussion on the issues presented.

One thread dealt with the issue as to the merits of the information 
hiding approach implicit with variable-based multiplexing, versus 
the information publication approach implicit with packet-based 
multiplexing.  In particular, Dave Bridgham and Randy Presuhn 
presented conflicting arguments as to these merits.  A voluntary action 
has been assigned asking each participant to post concise summaries of 
their positions.

A second thread dealt with the issues as to the difference between the 
information selection inherent with packet-based multiplexing versus 
the information integration inherent with variable-based 
multiplexing.  For example, a service provider might provision a 
customer-specific subset of the available management information 
based on community string.

Further, a third thread dealt with the goal of the Working Group, viz. 
to allow multiple, independent contributors to implement a single 
system.  In addition, three functional requirements were identified:

o  applicable system types (outside the scope of the Working 
   Group);
o  consistency with overall framework; and,
o  end-to-end performance.


ACTION ITEMS

The Chair assigned the following voluntary actions:

Aleksey Romanov: Please provide the Working Group with a URL for 
the proposal on agent extensibility that you posted some time ago (his 
response).

Bert  Wijnen, Jeff Case, and Dan Romanscieu: Please send ASCII, 
Postscript, or HTML versions of your presentation to the Chair so that 
your presentation may be included in the ftp archive.

Dave Bridgham and Randy Presuhn: Please post concise summaries of 
your position with respect to the efficacy of the proxy approach to the 
mailing list.

Andy Bierman, Editor for the entity mib Working Group: Please 
consider the relationship between packet-based multiplexing and the 
logical entity table, especially how proxy relates to chaining or 
referral of requests to logical entities.