Ipsilon Flow Management Protocol Specification for IPv4 Version 1.0
RFC 1953

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Network Working Group                                 P. Newman, Ipsilon
Request for Comments: 1953                         W. L. Edwards, Sprint
Category: Informational                               R. Hinden, Ipsilon
                                                     E. Hoffman, Ipsilon
                                                  F. Ching Liaw, Ipsilon
                                                        T. Lyon, Ipsilon
                                                    G. Minshall, Ipsilon
                                                                May 1996

        Ipsilon Flow Management Protocol Specification for IPv4
                              Version 1.0

Status of this Memo

   This document provides information for the Internet community.  This
   memo does not specify an Internet standard of any kind.  Distribution
   of this memo is unlimited.

IESG Note:

   This memo documents a private protocol for IPv4-based flows.  This
   protocol is NOT the product of an IETF working group nor is it a
   standards track document.  It has not necessarily benefited from the
   widespread and in depth community review that standards track
   documents receive.

Abstract

   The Ipsilon Flow Management Protocol (IFMP), is a protocol for
   allowing a node to instruct an adjacent node to attach a layer 2
   label to a specified IP flow.  The label allows more efficient access
   to cached routing information for that flow.  The label can also
   enable a node to switch further packets belonging to the specified
   flow at layer 2 rather than forwarding them at layer 3.

Table of Contents

   1. Introduction....................................................2
   2. Flow Types......................................................2
   3. IFMP Adjacency Protocol.........................................4
       3.1  Packet Format.............................................4
       3.2  Procedure.................................................7
   4. IFMP Redirection Protocol......................................10
       4.1  Redirect Message.........................................12
       4.2  Reclaim Message..........................................13
       4.3  Reclaim Ack Message......................................15
       4.4  Label Range Message......................................16

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RFC 1953                   IFMP Specification                   May 1996

       4.5  Error Message............................................17
   References........................................................19
   Security Considerations...........................................19
   Authors' Addresses................................................19

1. Introduction

   The Ipsilon Flow Management Protocol (IFMP), is a protocol for
   instructing an adjacent node to attach a layer 2 label to a specified
   IP flow. The label allows more efficient access to cached routing
   information for that flow and it allows the flow to be switched
   rather than routed in certain cases.

   If a network node's upstream and downstream links both redirect a
   flow at the node, then the node can switch the flow at the data link
   layer rather than forwarding it at the network layer.  The label
   space is managed at the downstream end of each link and redirection
   messages are sent upstream to associate a particular flow with a
   given label.  Each direction of transmission on a link is treated
   separately.

   If the flow is not refreshed by the time the lifetime field in the
   redirect message expires, then the association between the flow and
   the label is discarded.  A flow is refreshed by sending a redirect
   message, identical to the original, before the lifetime expires.

   Several flow types may be specified.  Each flow type specifies the
   set of fields from the packet header that are used to identify a
   flow.  There must be an ordering amongst the different flow types
   such that a most specific match operation may be performed.

   A particular flow is specified by a flow identifier.  The flow
   identifier for that flow gives the contents of the set of fields from
   the packet header as defined for the flow type to which it belongs.

   This document specifies the IFMP protocol for IPv4 on a point-to-
   point link.  The definition of labels, and the encapsulation of
   flows, are specified in a separate document for each specific data
   link technology.  The specification for ATM data links is given in
   [ENCAP].

2. Flow Types

   A flow is a sequence of packets that are sent from a particular
   source to a particular (unicast or multicast) destination and that
   are related in terms of their routing and any logical handling policy
   they may require.

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RFC 1953                   IFMP Specification                   May 1996