Network Working Group B. Adamson
Request for Comments: 5740 Naval Research Laboratory
Obsoletes: 3940 C. Bormann
Category: Standards Track Universitaet Bremen TZI
M. Handley
University College London
J. Macker
Naval Research Laboratory
November 2009
NACK-Oriented Reliable Multicast (NORM) Transport Protocol
Abstract
This document describes the messages and procedures of the Negative-
ACKnowledgment (NACK) Oriented Reliable Multicast (NORM) protocol.
This protocol can provide end-to-end reliable transport of bulk data
objects or streams over generic IP multicast routing and forwarding
services. NORM uses a selective, negative acknowledgment mechanism
for transport reliability and offers additional protocol mechanisms
to allow for operation with minimal a priori coordination among
senders and receivers. A congestion control scheme is specified to
allow the NORM protocol to fairly share available network bandwidth
with other transport protocols such as Transmission Control Protocol
(TCP). It is capable of operating with both reciprocal multicast
routing among senders and receivers and with asymmetric connectivity
(possibly a unicast return path) between the senders and receivers.
The protocol offers a number of features to allow different types of
applications or possibly other higher-level transport protocols to
utilize its service in different ways. The protocol leverages the
use of FEC-based (forward error correction) repair and other IETF
Reliable Multicast Transport (RMT) building blocks in its design.
This document obsoletes RFC 3940.
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved.
Adamson, et al. Standards Track [Page 1]
RFC 5740 NORM Protocol November 2009
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Table of Contents
1. Introduction and Applicability . . . . . . . . . . . . . . . . 4
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 5
1.2. NORM Data Delivery Service Model . . . . . . . . . . . . . 5
1.3. NORM Scalability . . . . . . . . . . . . . . . . . . . . . 7
1.4. Environmental Requirements and Considerations . . . . . . 8
2. Architecture Definition . . . . . . . . . . . . . . . . . . . 8
2.1. Protocol Operation Overview . . . . . . . . . . . . . . . 10
2.2. Protocol Building Blocks . . . . . . . . . . . . . . . . . 12
2.3. Design Trade-Offs . . . . . . . . . . . . . . . . . . . . 12
3. Conformance Statement . . . . . . . . . . . . . . . . . . . . 13
4. Message Formats . . . . . . . . . . . . . . . . . . . . . . . 15
4.1. NORM Common Message Header and Extensions . . . . . . . . 15
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