Subject: Protocol Action: IP Packet Delay Variation Metric for IPPM to Proposed Standard

From: The IESG <[email-masked]>
Date: Fri, 30 Aug 2002 07:59:15 -0400

The IESG has approved the Internet-Draft 'IP Packet Delay Variation 
Metric for IPPM' <draft-ietf-ippm-ipdv-10.txt> as a Proposed Standard.
This document is the product of the IP Performance Metrics Working 
Group.  The IESG contact persons are Allison Mankin and Scott Bradner.

Technical Summary
 
      This document specifies a metric for variation in delay of
      packets aross Internet paths. The metric is based on the
      difference in the One-Way-Delay of selected packets. This
      difference in delay is called "IP Packet Delay variation" or
      IPDV. The metric is based on the
      delay per se metric defined in RFC 2679.

      The metric is valid for measurements between two hosts both in
      the case that they have synchronized clocks and in the case that
      they are not synchronized.

      The IPDV metric can be used for sizing of play-out buffres for
      applications requiring the regular delivery of packets (for
      example, voice or video play-out). What is normally important in
      this case is the maximum delay variation, which is used to size
      play- out buffers for such applications]. Other uses of a delay
      variation metric are, for example, to determine the dynamics of
      queues within a network (or router) where the changes in delay
      variation can be linked to changes in the queue length process at
      a given link or a combination of links.

      In addition, this type of metric is particularly robust with
      respect to differences and variations of the clocks of the two
      hosts. This allows the use of the metric even if the two hosts
      that support the measurement points are not synchronized. In the
      latter case indications of reciprocal skew of the clocks can be
      derived from the measurement and corrections are possible. The
      related precision is often comparable with the one that can be
      achieved with synchronized clocks, being of the same order of
      magnitude of synchronization errors.

Working Group Summary

      There was good consensus on this document, and careful review to
      achieve a correct specification.

Protocol Quality

      The document was reviewwed for the IESG by Allison Mankin.