RFC 3366 (rfc3366) - Page 2 of 27
Advice to link designers on link Automatic Repeat reQuest (ARQ)
Alternative Format: Original Text Document
RFC 3366 Advice to Link Designers on Link ARQ August 2002
Table of Contents
1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . .2
1.1 Link ARQ. . . . . . . . . . . . . . . . . . . . . . . . . . .4
1.2 Causes of Packet Loss on a Link . . . . . . . . . . . . . . .5
1.3 Why Use ARQ?. . . . . . . . . . . . . . . . . . . . . . . . .6
1.4 Commonly-used ARQ Techniques. . . . . . . . . . . . . . . . .7
1.4.1 Stop-and-wait ARQ . . . . . . . . . . . . . . . . . . . . . .7
1.4.2 Sliding-Window ARQ. . . . . . . . . . . . . . . . . . . . . .7
1.5 Causes of Delay Across a Link . . . . . . . . . . . . . . . .8
2. ARQ Persistence . . . . . . . . . . . . . . . . . . . . . . 10
2.1 Perfectly-Persistent (Reliable) ARQ Protocols . . . . . . . 10
2.2 High-Persistence (Highly-Reliable) ARQ Protocols. . . . . . 12
2.3 Low-Persistence (Partially-Reliable) ARQ Protocols. . . . . 13
2.4 Choosing Your Persistency . . . . . . . . . . . . . . . . . 13
2.5 Impact of Link Outages. . . . . . . . . . . . . . . . . . . 14
3. Treatment of Packets and Flows. . . . . . . . . . . . . . . 15
3.1 Packet Ordering . . . . . . . . . . . . . . . . . . . . . . 15
3.2 Using Link ARQ to Support Multiple Flows. . . . . . . . . . 16
3.3 Differentiation of Link Service Classes . . . . . . . . . . 17
4. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . 19
5. Security Considerations . . . . . . . . . . . . . . . . . . 21
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . 21
7. Acknowledgements. . . . . . . . . . . . . . . . . . . . . . 22
8. References. . . . . . . . . . . . . . . . . . . . . . . . . 22
8.1 Normative References. . . . . . . . . . . . . . . . . . . . 22
8.2 Informative References. . . . . . . . . . . . . . . . . . . 23
9. Authors' Addresses. . . . . . . . . . . . . . . . . . . . . 26
10. Full Copyright Statement. . . . . . . . . . . . . . . . . . 27
1. Introduction
IP, the Internet Protocol [RFC 791], forms the core protocol of the
global Internet and defines a simple "connectionless" packet-switched
network. Over the years, Internet traffic using IP has been carried
over a wide variety of links, of vastly different capacities, delays
and loss characteristics. In the future, IP traffic can be expected
to continue to be carried over a very wide variety of new and
existing link designs, again of varied characteristics.
A companion document [DRAFTKARN02] describes the general issues
associated with link design. This document should be read in
conjunction with that and with other documents produced by the
Performance Implications of Link Characteristics (PILC) IETF
workgroup [RFC 3135, RFC 3155].
Fairhurst & Wood Best Current Practice