RFC 3487 (rfc3487) - Page 2 of 17
Requirements for Resource Priority Mechanisms for the Session Initiation Protocol (SIP)
Alternative Format: Original Text Document
RFC 3487 IEPREP SIP Requirements February 2003
1. Introduction
During emergencies, communications resources including telephone
circuits, IP bandwidth and gateways between the circuit-switched and
IP networks may become congested. Congestion can occur due to heavy
usage, loss of resources caused by the natural or man-made disaster
and attacks on the network during man-made emergencies. This
congestion may make it difficult for persons charged with emergency
assistance, recovery or law enforcement to coordinate their efforts.
As IP networks become part of converged or hybrid networks along with
public and private circuit-switched (telephone) networks, it becomes
necessary to ensure that these networks can assist during such
emergencies.
There are many IP-based services that can assist during emergencies.
This memo only covers requirements for real-time communications
applications involving the Session Initiation Protocol (SIP) [1],
including voice-over-IP, multimedia conferencing and instant
messaging/presence.
This document takes no position as to which mode of communication is
preferred during an emergency, as such discussion appears to be of
little practical value. Based on past experience, real-time
communications is likely to be an important component of any overall
suite of applications, particularly for coordination of emergency-
related efforts.
As we will describe in detail below, such Session Initiation Protocol
(SIP) [1] applications involve at least five different resources that
may become scarce and congested during emergencies. In order to
improve emergency response, it may become necessary to prioritize
access to such resources during periods of emergency-induced resource
scarcity. We call this "resource prioritization".
This document describes requirements rather than possible existing or
new protocol features. Although it is scoped to deal with SIP-based
applications, this should not be taken to imply that mechanisms have
to be SIP protocol features such as header fields, methods or URI
parameters.
The document is organized as follows. In Section 2, we explain core
technical terms and acronyms that are used throughout the document.
Section 3 describes the five types of resources that may be subject
to resource prioritization. Section 4 enumerates four network
hybrids that determine which of these resources are relevant. Since
the design choices may be constrained by the assumptions placed on
Schulzrinne Informational