Delayed Duplication Attribute in the Session Description Protocol
draft-ietf-mmusic-delayed-duplication-01
MMUSIC A. Begen
Internet-Draft Cisco
Intended status: Standards Track Y. Cai
Expires: September 21, 2013 Microsoft
H. Ou
Cisco
March 20, 2013
Delayed Duplication Attribute in the Session Description Protocol
draft-ietf-mmusic-delayed-duplication-01
Abstract
A straightforward approach to provide protection against packet
losses due to network outages with a longest duration of T time units
is to simply duplicate the original packets and send each copy
separated in time by at least T time units. This approach is
commonly referred to as Time-shifted Redundancy, Temporal Redundancy
or simply Delayed Duplication. This document defines an attribute to
indicate the presence of temporally redundant media streams and the
duplication delay in the Session Description Protocol.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 21, 2013.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
Begen, et al. Expires September 21, 2013 [Page 1]
Internet-Draft Delayed Duplication Attribute in SDP March 2013
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Notation . . . . . . . . . . . . . . . . . . . . . 4
3. The 'duplication-delay' Attribute . . . . . . . . . . . . . . . 4
4. SDP Examples . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
6.1. Registration of SDP Attributes . . . . . . . . . . . . . . 7
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References . . . . . . . . . . . . . . . . . . . 8
8.2. Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
Begen, et al. Expires September 21, 2013 [Page 2]
Internet-Draft Delayed Duplication Attribute in SDP March 2013
1. Introduction
Consider that a media sender transmits an original source packet and
transmits its duplicate after a certain delay following the original
transmission. If a network outage hits the original transmission,
the expectation is that the second transmission arrives at the
receiver. Alternatively, the second transmission may be hit by an
outage and gets dropped, and the original transmission completes
successfully. On the receiver side, both transmissions can also
arrive and in that case, the receiver (or the node that does the
duplicate suppression) needs to identify the duplicate packets and
discard them appropriately, producing a duplicate-free stream.
Delayed duplication can be used in a variety of multimedia
applications where there is sufficient bandwidth for the duplicated
traffic and the application can tolerate the introduced delay.
However, it must be used with care since it might easily result in a
new series of denial-of-service attacks. Furthermore, delayed
duplication must not be used in cases where the primary cause of
packet loss is congestion, rather than a network outage due to a
Show full document text