RFC 3374 (rfc3374) - Page 2 of 14

Problem Description: Reasons For Performing Context Transfers Between Nodes in an IP Access Network

RFC 3374           Context Transfer Problem Statement     September 2002


Table of Contents

   1.0   Introduction................................................2
   2.0   Reference Definitions.......................................3
   3.0   Scope of the Context Transfer Problem.......................3
   4.0   The Need for Context Transfer...............................4
   4.1   Fast Context Transfer-candidate Service Re-establishment....4
   4.1.1 Authentication, Authorization, and Accounting (AAA).........4
   4.1.2 Header Compression..........................................5
   4.1.3 Quality of Service (QoS)....................................6
   4.2   Interoperability............................................6
   5.0   Limitations on Context Transfer.............................7
   5.1   Router Compatibility........................................7
   5.2   Requirement to Re-initialize Service from Scratch...........7
   5.3   Suitability for the Particular Service......................7
   5.4   Layer 2 Solutions Better....................................7
   6.0   Performance Considerations..................................8
   7.0   Security Considerations.....................................8
   8.0   Recommendations.............................................9
   9.0   Acknowledgements............................................9
   10.0  References.................................................10
   11.0  Complete List of Authors' Addresses........................12
   12.0  Full Copyright Statement...................................14

1.0 Introduction

   In networks where the hosts are mobile, the routing path through the
   network must often be changed in order to deliver the host's IP
   traffic to the new point of access.  Changing the basic routing path
   is the job of a IP mobility protocol, such as Mobile IPv4 [1] and
   Mobile IPv6 [2].  But the success of real time services such as VoIP
   telephony, video, etc., in a mobile environment depends heavily upon
   the minimization of the impact of this traffic redirection.  In the
   process of establishing the new routing path, the nodes along the new
   path must be prepared to provide similar routing treatment to the IP
   packets as was provided along the old routing path.

   In many cases, the routing treatment of IP packets within a network
   may be regulated by a collection of context transfer-candidate
   services that influence how packets for the host are treated.  For
   example, whether a particular host has the right to obtain any
   routing at all out of the local subnet may depend on whether the host
   negotiated a successful AAA exchange with a network access server at
   some point in the past.  Establishing these services initially
   results in a certain amount of related state within the network and
   requires a perhaps considerable amount of time for the protocol





Kempf                        Informational