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Editor's Note: These minutes have not been edited.
Meeting Minutes -- 38th IETF; Memphis, TN
Reported by Ken Jones
Area: Operational and Management Requirements
Working Group: ptopomib
Date: April 9, 1997
WG Chair:
Ken Jones <kjones@baynetworks.com>
Area Advisor:
Andy Bierman <abierman@cisco.com>
-------------------------
Summary
=======
The Ptopo WG met on Wednesday, april 9th from 1:00 to 3:15.
55 people attended the session.
Reading Material
================
ID-1: Network Element Object MIB (Neo-MIB)
draft-tackabury-neo-mib-00.txt
ID-2: Physical Topology Framework
draft-kjones-ptopo-framework-00.txt
ID-3: Physical Topology MIB and Discovery Protocol
draft-bierman-ptopo-MIB-proto-00.txt
ID-4: Physical Topology Terminology
draft-malachi-topology-terms-00.txt
Agenda Review - Jones
=====================
Ken Jones presented the agenda, which was accepted with
some changes in the order of presentatons. The proposed agenda
called for reviewing the 4 IDs, and then to spend
the rest of the time discussing key issues, with a goal of
reaching consensus within the group if possible, and deferring
contentious issues to the mailing list.
The following was the final agenda:
o Agenda Review
o Review IDs
o Framework - Ken Jones
o Neo-MIB - Wayne Tackabury
o MIB and Discovery Protocol - Andy Bierman
o Terminology - (not reviewed due to author not present)
o Issues Review (list of issues provided below)
o Discussion on need for Interim meeting
Physical Topology Framework (ID-2) - Jones
==========================================
Ken Jones reviewed the framework document. A copy of the
ID and the presentation can be found in the ptopo
archives (ftp.3com.com). Key points and issues raised include
the following:
o the definition of physical topology is the external
interconnection of physical ports. Can be 1:1 or 1:n. It
is a linear relationship - there is no concept of hierarchy
required.
o the common MIB should be independent of the topology
mechanism(s) used and should represent the agent's local view
of the physical topology. That view may be incomplete and/or
redundant. The MIB should also contain information about
other agents that have been discovered by this agent. These
other agents may contain physical topology data.
o Security - there is an issue that agent discovery and
physical topology information may be a security concern in some
environments.
o Use of datalink information to determine physical topology.
The framework document describes a method of determining physical
topology based on detecting which MAC addresses have been seen on
which ports. There was a question about whether this datalink
information should be used to understand physical topology. It was
pointed out that datalink info is a good way to identify leaf devices
without requiring them to implement an active topology mechanism or
the PTOPO MIB.
Network Element Object MIB (ID-1) - Tackabury
=============================================
Wayne Tackabury reviewed the Neo-MIB document. A copy of his
presentation and the ID can be found in the PTOPO
archive (ftp.3com.com). Key points and issues raised include the
following:
o this MIB supports both the local topology agent and the
topology server agent. It is also extensible to layers above
physical topology. Wayne presented an example of how vlan
topology would be represented in the MIB
o it was suggested that the identifier used to indicate
the topology mechanism used to collect the data be included in
the index. This would allow a management application to readily
retrieve all topology information obtained through a particular
mechanism.
Physical Topology MIB and Discovery Protocol (ID-3) - Bierman
=============================================================
Andy Bierman reviewed the MIB and discovery protocol document. A copy
of his presentation and the ID can be found in the PTOPO archive
(ftp.3com.com). Key points and issues raised include the following:
o the entity MIB would be extended to support a read-only chassis
ID and port IDs. These IDs would be persistent across power cycles.
o the MIB contains both physical connectivity information and
agent identification information, as described in the framework
document. the MIB provides local topology - it is not a topology
server.
o The MIB does not allow for representation of partial topology
information (e.g. if remote port is not known), or for ambiguous
information (e.g. several devices are known to exist downstream
from a port, but the actual physical connections are not known (also
known as a cloud).
o There was a question as to whether the device ID would be
universally required to be supplied by all topology mechanisms.
o there is a 128-byte limit on the size of an index, so we need
to be careful how many strings we use as indices.
o the PTOPO Discovery Protocol is proposed as an example
mechanism that could be used to populate the PTOPO MIB. The
mechanism proposed would be for store and forward devices since
the discovery packets should not be forwarded by a device and
must be sent on all ports, including spanning-tree-blocked ports.
o it was pointed out that the PTOPO agent is different than
the topology mechanism "application" and we should be careful
not to confuse the two.
Issues Discussion - Jones
=========================
Ken Jones led a discussion on a number of issues. Two major
issues were discussed and consensus was reached. The other
issues will be discussed on the mailing list. The list of issues
can be found in the presentations directory in the PTOPO archives.
Local Topology vs Topology Server
The issue is whether the WG should focus just on local topology
for now or whether it should include a topology server. The MIB
requirements for both could be very similar, although the topology
server could have additional requirements. A proposal was made
to focus on local topology for now and either work on the topology
server as a future WG effort or possibly move it to DISMAN or some
other WG. Topology issues such as connections to local printers
through a printer port would also not be part of local topology
MIB. A straw vote was taken on this issue and the group
felt strongly that it should focus on local topology for now.
Do we need to specify topology mechanisms
The group felt very strongly that we need to specify one or more
mechanisms in order to provide enough information to allow
interoperable implementations. It was agreed that we can't limit
the MIB or the implementations to a single mechanism - we must allow
use of existing mechanisms, both standard and proprietary. We
must allow the overlapping use of different mechanisms. Data in the
MIB should be identified with the topology mechanism used to discover
that data.
There were several other issues that we did not have time to cover.
The following is a brief summary of these issues:
o entity MIB extensions - are these satisfactory and are there
issues with requiring implementation of portions of the entity MIB.
o agent identification - is this through a t-address?
o device identification - should this be more flexible.for example
should it be read/write.
o should the MIB include end-station (leaf) topology information.
The response from San Jose was a strong yes.
o how does the MIB accomodate redundant or ambiguous information -
e.g. multiple agents detected on a port, and multiple device IDs
detected on a port.
o Should there be a separate table for connection info and agent id?
o how useful are time filters for topology. The RMON group has
positive feedback on their usefulness.
o topology corner cases - non-PTOPO devices, multiple agents in
a chassis, multiple links between devices, rings, busses (see
framework document).
o can the instance of the topology mechanism be used to bound
the topology gathering process (see framework document)
o what's the right way to detect and process topology changes.
Interim Meeting Discussion
==========================
We discussed the need to get active discourse occuring on the mail
list. It seems that most of the work prior to the Memphis meeting
happened during the 3 weeks prior to the cutoff date (Wayne was
the exception). An interim meeting would have the benefit of
getting work done 3 weeks ahead of time, but we really need
a more focused effort from the group.
It was agreed that the chairman would determine whether sufficient
progress was being made on the mail list, and if not would call for
an interim meeting to be held sometime in June. We will also try
to coordinate with other Operations and Management WGs that may be
planning interim meetings as well.