BT's eXtended Network Quality RTP Control Protocol Extended Reports (RTCP XR XNQ)
RFC 5093

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Network Working Group                                            G. Hunt
Request for Comments: 5093                                            BT
Category: Informational                                    December 2007

  BT's eXtended Network Quality RTP Control Protocol Extended Reports
                             (RTCP XR XNQ)

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

IESG Note

   The IESG has concerns about vendor code points allocation in this
   small namespace and might not approve similar documents in the
   future.

Abstract

   This document describes an RTCP XR report block, which reports packet
   transport parameters.  The report block was developed by BT for pre-
   standards use in BT's next-generation network.  This document has
   been produced to describe the report block in sufficient detail to
   register the block type with IANA in accordance with the
   Specification Required policy of RFC 3611.  This specification does
   not standardise the new report block for use outside BT's network.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 2
   2.  Requirements Notation . . . . . . . . . . . . . . . . . . . . . 2
   3.  Extended Network Quality (XNQ) Report Block . . . . . . . . . . 2
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
   5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 6
     6.1.  Normative References  . . . . . . . . . . . . . . . . . . . 6
     6.2.  Informative References  . . . . . . . . . . . . . . . . . . 6

Hunt                         Informational                      [Page 1]
RFC 5093            RTCP XR eXtended Network Quality       December 2007

1.  Introduction

   A set of metrics of packet-transport quality has been defined by BT
   for pre-standards use in its network.  These metrics are known as
   "XNQ" for "eXtended Network Quality".  This document defines an
   RTCP-XR Report Block to transport the XNQ measures from an RTP end
   system to its peer, using the extension mechanism defined in [1].

   The metrics are designed to supplement the packet-loss metric in RTCP
   [2] and the roundtrip delay measurement provided by RTCP.  They
   provide metrics for IP Packet Delay Variation based on the IPDV
   metric defined in [3], metrics reporting the activity of the RTP end
   system's receiver's jitter buffer, and metrics reporting "errored"
   and "severely errored" seconds.

   This document has been produced to describe the report block in
   sufficient detail to register the block type with IANA in accordance
   with the Specification Required policy of [1].  This specification
   does not standardise the new report block for use outside BT's
   network.

   Work in progress on RTCP HR [5] is likely to obsolete these metrics
   and the RTCP-XR Report Block defined here.

2.  Requirements Notation

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [4].

3.  Extended Network Quality (XNQ) Report Block

   A set of metrics of packet-transport quality has been defined by BT
   for pre-standards use in its network.  These metrics are known as
   "XNQ" for "eXtended Network Quality".

   This document defines an RTCP-XR Report Block using the extension
   mechanism defined in [1].  The new Report Block provides transport of
   the XNQ measures from an RTP end system to its peer.

   The metrics are described in the following text.  However, some
   additional explanation is required for the metrics vmaxdiff, vrange,
   vsum, and c, which measure aspects of packet delay variation.  The
   metrics are based on the measure known as IP Packet Delay Variation
   (IPDV) defined in [3].  The IPDV of a packet is the amount by which
   the packet was delayed in the network, minus the amount a reference
   packet was delayed in the network.  The reference packet is usually
   the first packet of the connection.  IPDV is a signed quantity.

Hunt                         Informational                      [Page 2]
RFC 5093            RTCP XR eXtended Network Quality       December 2007

   The metric vrange is the difference (longest minus shortest) between
   the longest and shortest network packet delays seen over the duration
   of the connection to date.  The metric vrange is usually a positive
   quantity, but may be zero if the packet delay is exactly constant
   over the lifetime of the connection to date.

   The metric vmaxdiff is found as follows.  For each RTCP measurement
   cycle, find the difference (longest minus shortest) between the
   longest and shortest network packet delays within that measurement