Metering and Marking Behaviour of PCN-Nodes
RFC 5670
Network Working Group P. Eardley, Ed.
Request for Comments: 5670 BT
Category: Standards Track November 2009
Metering and Marking Behaviour of PCN-Nodes
Abstract
The objective of Pre-Congestion Notification (PCN) is to protect the
quality of service (QoS) of inelastic flows within a Diffserv domain
in a simple, scalable, and robust fashion. This document defines the
two metering and marking behaviours of PCN-nodes. Threshold-metering
and -marking marks all PCN-packets if the rate of PCN-traffic is
greater than a configured rate ("PCN-threshold-rate"). Excess-
traffic-metering and -marking marks a proportion of PCN-packets, such
that the amount marked equals the rate of PCN-traffic in excess of a
configured rate ("PCN-excess-rate"). The level of marking allows
PCN-boundary-nodes to make decisions about whether to admit or
terminate PCN-flows.
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.
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Eardley Standards Track [Page 1]
RFC 5670 PCN metering and marking November 2009
modifications of such material outside the IETF Standards Process.
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Table of Contents
1. Introduction ....................................................2
1.1. Terminology ................................................4
1.1.1. Requirements Language ...............................5
2. Specified PCN-Metering and -Marking Behaviours ..................5
2.1. Behaviour Aggregate Classification Function ................5
2.2. Dropping Function ..........................................5
2.3. Threshold-Meter Function ...................................6
2.4. Excess-Traffic-Meter Function ..............................6
2.5. Marking Function ...........................................7
3. Security Considerations .........................................7
4. Acknowledgements ................................................8
5. References ......................................................8
5.1. Normative Reference ........................................8
5.2. Informative References .....................................8
Appendix A. Example Algorithms ...................................11
A.1. Threshold-Metering and -Marking ...........................11
A.2. Excess-Traffic-Metering and -Marking ......................12
Appendix B. Implementation Notes .................................13
B.1. Competing-Non-PCN-Traffic .................................13
B.2. Scope .....................................................14
B.3. Behaviour Aggregate Classification ........................15
B.4. Dropping ..................................................15
B.5. Threshold-Metering ........................................17
B.6. Excess-Traffic-Metering ...................................18
B.7. Marking ...................................................19
1. Introduction
The objective of Pre-Congestion Notification (PCN) is to protect the
quality of service (QoS) of inelastic flows within a Diffserv domain
in a simple, scalable, and robust fashion. Two mechanisms are used:
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