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nimrod-minutes-95apr.txt
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1995-05-26
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CURRENT_MEETING_REPORT_
Reported by Isidro Castineyra/Bolt Beranek and Newman
Minutes of the New Internet Routing and Addressing Architecture
Working Group (NIMROD)
Preface
The NIMROD Working Group met on Tuesday, 4 April, and on Wednesday, 5
April. The agenda for the meeting was:
o Tuesday
- Agenda bashing/Announcements
- Overview of the Deployment Document (Charlie Lynn)
- Configuration vs. Discovery (Martha Steenstrup)
- Discussion
o Wednesday
- What is in the Nimrod Model (Martha Steenstrup and Isidro
Castineyra)
- Software Architecture (Charlie Lynn)
- Discussion
- Open Issues and Work Plan
Deployment Document
Charlie Lynn gave an overview of the Deployment Document. He discussed
strategies for the gradual integration of Nimrod in the Internet.
Configuration vs. Discovery
Martha Steenstrup presented a list of information elements that could be
obtained by either configuration or discovery. For each element, Martha
discussed the trade-offs and the current thoughts on what to do with
that element. Highlights of her presentation follow.
o The goal is to make both a ``plug-and-play'' system and to make
everything configurable.
o Configured items:
- At Node Representatives: adjacency formation constraints,
association constraints, set of locator elements for component
nodes.
- At Endpoint Representatives: EIDs and names of endpoints,
association constraints, multicast group membership of
endpoints.
- At Forwarding Agents: traffic restrictions.
- At Agents: type of agent, EID of agent, nodes on which behalf
the agent acts (configured).
Martha will be posting the slides she used to the working group mailing
list.
Nimrod Model/Bootstrap I
Isidro Castineyra described a bootstrap model for Nimrod. Highlights of
his talk follow:
o Nimrod specifies only what happens between nodes.
o The internal operation of an ``atomic'' node is not Nimrod's
concern.
o There are two kinds of locators: flat and hierarchical.
o The flat locator of a node is used in Basic Routing (later) to do
flat routing within the components node of nodes. This mode of
routing is used to bootstrap hierarchical routing.
o The Nimrod part of a hierarchical locator is a sequence of up to
256 locator elements, where a locator element is a 16-bit string.
o Hierarchical locator is ``inside'' a node if its Nimrod part is
both prefixed by the node's locator and longer than the node's
locator.
o For a given node and for a given hierarchical locator inside the
node, the first element following the original node's locator
identifies a component node. This 16-bit string is referred to as
the node's ``local element.'' Therefore, nodes are limited to
having no more than 216 component nodes.
o For a given node, the assignment of the values of local element to
component nodes is independent both of assignment of local elements
inside the node's subnode and in nodes that subsum the given node.
o Basic routing is based only on connectivity (i.e., it does not take
into account considerations of quality of service or service
restrictions).
o Basic routing is used for agent discovery and to enable
communication between agents that reside in different nodes. The
advanced routing capabilities of Nimrod are built over basic
routing.
o Basic routing is very much like a one-level OSPF. Basic routing is
built over a flooding protocol which works between the set of
nodes. When a message is flooded, every node in the set receives a
copy of the message which is delivered to the node's
representative(s).
o Information flooded includes: identity of neighboring component
nodes, what agents the node includes.
Slides from this presentation will be posted to the mailing list.
Nimrod Model/Bootstrap II
Martha Steenstrup described an alternative bootstrap model. Highlights
of her presentation follow:
o Besides interaction between nodes, Nimrod specifies interaction
between agents within a node. These agents might reside in
separate ``boxes'' and be connected via IP.
o Agents need not reside in the node on whose behalf they act.
o Agents advertise their presence and characteristics using a
reliable hop-by-hop flooding protocol. This flooding is used to
construct a next-hop agent forwarding table using an algorithm
similar (but not identical) to standard distance vector algorithms.
The slides for this presentation will be sent to the mailing list.
Software Architecture
Charlie Lynn presented the current software architecture for the BBN
implementation of Nimrod.
Path Management Issues
Martha Steenstrup listed alternatives for path setup.
o Should path labels be globally unique or path unique.
o Path constructions: should we use hierarchical routes or
hierarchical paths.
o Path repair: should it be done at any node; at initiator or
target; between successive hops?