Signaled Preemption Priority Policy Element
RFC 3181
| Document | Type |
RFC - Proposed Standard
(October 2001; No errata)
Obsoletes RFC 2751
|
|
|---|---|---|---|
| Last updated | 2013-03-02 | ||
| Stream | IETF | ||
| Formats | plain text pdf html bibtex | ||
| Stream | WG state | (None) | |
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 3181 (Proposed Standard) | |
| Consensus Boilerplate | Unknown | ||
| Telechat date | |||
| Responsible AD | (None) | ||
| Send notices to | (None) | ||
Network Working Group S. Herzog
Request for Comments: 3181 PolicyConsulting.Com
Obsoletes: 2751 October 2001
Category: Standards Track
Signaled Preemption Priority Policy Element
Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2001). All Rights Reserved.
Abstract
This document describes a preemption priority policy element for use
by signaled policy based admission protocols (such as the Resource
ReSerVation Protocol (RSVP) and Common Open Policy Service (COPS).
Preemption priority defines a relative importance (rank) within the
set of flows competing to be admitted into the network. Rather than
admitting flows by order of arrival (First Come First Admitted)
network nodes may consider priorities to preempt some previously
admitted low priority flows in order to make room for a newer, high-
priority flow.
This memo corrects an RSVP POLICY_DATA P-Type codepoint assignment
error in RFC 2751.
Herzog Standards Track [Page 1]
RFC 3181 Signaled Preemption Priority Policy Element October 2001
Table of Contents
1 Introduction .....................................................2
2 Scope and Applicability ..........................................3
3 Stateless Policy .................................................3
4 Policy Element Format ............................................4
5 Priority Merging Issues ..........................................5
5.1 Priority Merging Strategies ...................................6
5.1.1 Take priority of highest QoS .................................6
5.1.2 Take highest priority ........................................7
5.1.3 Force error on heterogeneous merge ...........................7
5.2 Modifying Priority Elements ...................................7
6 Error Processing .................................................8
7 IANA Considerations ..............................................8
8 Security Considerations ..........................................8
9 References .......................................................9
10 Author's Address ...............................................9
Appendix A: Example ...............................................10
A.1 Computing Merged Priority ....................................10
A.2 Translation (Compression) of Priority Elements ...............11
Full Copyright Statement ..........................................12
1 Introduction
This document describes a preemption priority policy element for use
by signaled policy based admission protocols (such as [RSVP] and
[COPS]).
Traditional Capacity based Admission Control (CAC) indiscriminately
admits new flows until capacity is exhausted (First Come First
Admitted). Policy based Admission Control (PAC) on the other hand
attempts to minimize the significance of order of arrival and use
policy based admission criteria instead.
One of the more popular policy criteria is the rank of importance of
a flow relative to the others competing for admission into a network
node. Preemption Priority takes effect only when a set of flows
attempting admission through a node represents overbooking of
resources such that based on CAC some would have to be rejected.
Preemption priority criteria help the node select the most important
flows (highest priority) for admission, while rejecting the low
priority ones.
Network nodes which support preemption should consider priorities to
preempt some previously admitted low-priority flows in order to make
room for a newer, high-priority flow.
Herzog Standards Track [Page 2]
RFC 3181 Signaled Preemption Priority Policy Element October 2001
This document describes the format and applicability of the
preemption priority represented as a policy element in [RSVP-EXT].
2 Scope and Applicability
The Framework document for policy-based admission control [RAP]
describes the various components that participate in policy decision
making (i.e., PDP, PEP and LDP). The emphasis of PREEMPTION_PRI
elements is to be simple, stateless, and light-weight such that they
could be implemented internally within a node's LDP (Local Decision
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