Signaled Preemption Priority Policy Element
RFC 3181
Document | Type |
RFC - Proposed Standard
(October 2001; No errata)
Obsoletes RFC 2751
|
|
---|---|---|---|
Author | Shai Herzog | ||
Last updated | 2013-03-02 | ||
Stream | Internent Engineering Task Force (IETF) | ||
Formats | plain text html pdf htmlized (tools) htmlized 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 Point). Certain base assumptions are made in the usage model for PREEMPTION_PRI elements: - They are created by PDPsShow full document text