Architectural Implications of Link Indications
RFC 4907
Network Working Group B. Aboba, Ed.
Request for Comments: 4907 Internet Architecture Board
Category: Informational IAB
June 2007
Architectural Implications of Link Indications
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.
Copyright Notice
Copyright (C) The IETF Trust (2007).
Abstract
A link indication represents information provided by the link layer
to higher layers regarding the state of the link. This document
describes the role of link indications within the Internet
architecture. While the judicious use of link indications can
provide performance benefits, inappropriate use can degrade both
robustness and performance. This document summarizes current
proposals, describes the architectural issues, and provides examples
of appropriate and inappropriate uses of link indications.
IAB Informational [Page 1]
RFC 4907 Link Indications June 2007
Table of Contents
1. Introduction ....................................................3
1.1. Requirements ...............................................3
1.2. Terminology ................................................3
1.3. Overview ...................................................5
1.4. Layered Indication Model ...................................7
2. Architectural Considerations ...................................14
2.1. Model Validation ..........................................15
2.2. Clear Definitions .........................................16
2.3. Robustness ................................................17
2.4. Congestion Control ........................................20
2.5. Effectiveness .............................................21
2.6. Interoperability ..........................................22
2.7. Race Conditions ...........................................22
2.8. Layer Compression .........................................25
2.9. Transport of Link Indications .............................26
3. Future Work ....................................................27
4. Security Considerations ........................................28
4.1. Spoofing ..................................................28
4.2. Indication Validation .....................................29
4.3. Denial of Service .........................................30
5. References .....................................................31
5.1. Normative References ......................................31
5.2. Informative References ....................................31
6. Acknowledgments ................................................40
Appendix A. Literature Review .....................................41
A.1. Link Layer .................................................41
A.2. Internet Layer .............................................53
A.3. Transport Layer ............................................55
A.4. Application Layer ..........................................60
Appendix B. IAB Members ...........................................60
IAB Informational [Page 2]
RFC 4907 Link Indications June 2007
1. Introduction
A link indication represents information provided by the link layer
to higher layers regarding the state of the link. While the
judicious use of link indications can provide performance benefits,
inappropriate use can degrade both robustness and performance.
This document summarizes the current understanding of the role of
link indications within the Internet architecture, and provides
advice to document authors about the appropriate use of link
indications within the Internet, transport, and application layers.
Section 1 describes the history of link indication usage within the
Internet architecture and provides a model for the utilization of
link indications. Section 2 describes the architectural
considerations and provides advice to document authors. Section 3
describes recommendations and future work. Appendix A summarizes the
literature on link indications, focusing largely on wireless Local
Area Networks (WLANs).
1.1. Requirements
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 [RFC2119].
1.2. Terminology
Access Point (AP)
A station that provides access to the fixed network (e.g., an
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