INTERNATIONAL TELECOMMUNICATION UNION
FOCUS GROUP ON IPTV
TELECOMMUNICATION
STANDARDIZATION SECTOR
FG IPTV-C-0534
English only
STUDY PERIOD 2005-2008
4th FG IPTV meeting:
Bled, 7 – 11 May 2007
WG(s): 4
CONTRIBUTION
Source:
Korea (Republic of)
Title:
Updated texts for QoS of IPTV multicast on FG IPTV-DOC-61
This contribution proposes the updated section 6.4 “QoS of IPTV multicast” in FG IPTV-DOC0061 (IPTV Multicast Frameworks).
1. Introduction
At last FG IPTV meeting in Mountain View, WG4 has decided to start the standardization activity
for “IPTV Multicast Frameworks”. This document describes functional requirements and
frameworks of supporting multicast capabilities in terms of IPTV network control.
Specially, the section 6.4 “QoS of IPTV multicast” describes various QoS issues in multicast
delivery for IPTV traffic in network domain.
We think that resource reservation and congestion control are needed to guarantee and maintain the
QoS of IPTV multicast
2. Proposal
We propose to update the section 6.4 “QoS of IPTV multicast” with the following texts.
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Contact:
YoungHwna Kwon(ICU), Jun Kyun Choi
(ICU), Young-il Seo(KT), Eun-Joo Jo(TTA),
Min-Gyung Kim(KT)
Korea (Republic of)
Tel:
Fax:
Email
+82-42-866-6272
+82-42-866-6226
[email protected],
[email protected], [email protected],
[email protected], [email protected]
Attention: This is a document submitted to the work of ITU-T and is intended for use by the participants to the activities of ITU-T's
Focus Group on IPTV, and their respective staff and collaborators in their ITU-related work. It is made publicly available for
information purposes but shall not be redistributed without the prior written consent of ITU. Copyright on this document is owned by
the author, unless otherwise mentioned. This document is not an ITU-T Recommendation, an ITU publication, or part thereof.
-2FG IPTV-C-0534
6.4 QoS of IPTV multicast
It is important issue to guarantee and maintain the QoS of IPTV multicast when delivering contents
for IPTV users. Resource reservation is necessary to guarantee the QoS of IPTV multicast and
congestion control is necessary to maintain the QoS of IPTV multicast.
Resource reservation mechanism can guarantee the multicast resource on multicast tree by
bounding the delays and jitters and by preventing the loss of video traffic. Specially, resource
reservation in IPTV multicast has the following characteristics.

Pre-reservation
Pre-reservation is reserved multicast resource before transferring IPTV traffic. It is more
benefit than dynamic reservation mechanism because of dynamic membership and a lot of
receivers. And, it is simple to control and maintain multicast resource.

Aggregated bandwidth reservation
Aggregated bandwidth reservation is reserved for a bundle of channels of IPTV traffic to
access node and several channels can share common resource. It is more benefit than
channel-based reservation because of scalability and channel zapping time.
Network Congestion can cause the QoS degrading of IPTV multicast. Therefore, congestion control
mechanism is needed to maintain the network status stably. Specially, congestion control in IPTV
multicast has the following characteristics.

Early Dropping
Early Dropping drops IPTV packets when the system load exceeds a certain drop rate over
before congestion occurs. By doing so, it can preserve the QoS of IPTV multicast from
congestion.

Class-based Dropping
Class-based Dropping drops the lower class of traffic. In this scheme, IPTV multicast traffic
has a higher priority than unicast traffic and data traffic because IPTV multicast traffic
transports to many IPTV users.
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