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 20071. 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
datatracker.ietf.org