RFC 3374 (rfc3374) - Page 3 of 14
Problem Description: Reasons For Performing Context Transfers Between Nodes in an IP Access Network
Alternative Format: Original Text Document
RFC 3374 Context Transfer Problem Statement September 2002
exchanges. If the host is required to re-establish those services by
the same process as it uses to initially establish them, delay-
sensitive real time traffic may be seriously impacted.
An alternative is to transfer enough information on the context
transfer-candidate service state, or context, to the new subnet so
that the services can be re-established quickly, rather than require
the mobile host to establish them from scratch. The transfer of
service context may be advantageous in minimizing the impact of host
mobility on, for example, AAA, header compression, QoS, policy, and
possibly sub-IP protocols and services such as PPP. Context transfer
at a minimum can be used to replicate the configuration information
needed to establish the respective protocols and services. In
addition, it may also provide the capability to replicate state
information, allowing stateful protocols and services at the new node
to be activated along the new path with less delay and less signaling
overhead.
In this document, a case is made for why the Seamoby Working Group
should investigate context transfer.
2.0 Reference Definitions
Context
The information on the current state of a service required to re-
establish the service on a new subnet without having to perform
the entire protocol exchange with the mobile host from scratch.
Context Transfer
The movement of context from one router or other network entity to
another as a means of re-establishing specific services on a new
subnet or collection of subnets.
Context Transfer Candidate Service
A service that is a candidate for context transfer. In this
document, only services that are concerned with the forwarding
treatment of packets, such as QoS and security, or involve
granting or denying the mobile host access to the network, such as
AAA, are considered to be context transfer-candidate services.
3.0 Scope of the Context Transfer Problem
The context transfer problem examined in this document is restricted
to re-establishing services for a mobile host that are, in some
sense, related to the forwarding treatment of the mobile host's
Kempf Informational