Licklider Transmission Protocol - Motivation
RFC 5325
| Document | Type |
RFC - Informational
(September 2008; No errata)
Was draft-irtf-dtnrg-ltp-motivation (dtnrg RG)
|
|
|---|---|---|---|
| Last updated | 2015-10-14 | ||
| Stream | IRTF | ||
| Formats | plain text pdf html bibtex | ||
| Stream | IRTF state | (None) | |
| Consensus Boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | RFC 5325 (Informational) | |
| Telechat date | |||
| Responsible AD | Russ Housley | ||
| Send notices to | ipr@ietf.org. | ||
Network Working Group S. Burleigh
Request for Comments: 5325 NASA/Jet Propulsion Laboratory
Category: Informational M. Ramadas
ISTRAC, ISRO
S. Farrell
Trinity College Dublin
September 2008
Licklider Transmission Protocol - Motivation
Status of This Memo
This memo defines an Experimental Protocol for the Internet
community. It does not specify an Internet standard of any kind.
Discussion and suggestions for improvement are requested.
Distribution of this memo is unlimited.
IESG Note
This RFC is not a candidate for any level of Internet Standard. It
represents the consensus of the Delay Tolerant Networking (DTN)
Research Group of the Internet Research Task Force (IRTF). See RFC
3932 for more information.
Abstract
This document describes the motivation for the development of the
Licklider Transmission Protocol (LTP) designed to provide
retransmission-based reliability over links characterized by
extremely long message round-trip times (RTTs) and/or frequent
interruptions in connectivity. Since communication across
interplanetary space is the most prominent example of this sort of
environment, LTP is principally aimed at supporting "long-haul"
reliable transmission in interplanetary space, but it has
applications in other environments as well.
In an Interplanetary Internet setting deploying the Bundle protocol,
LTP is intended to serve as a reliable convergence layer over
single-hop deep-space radio frequency (RF) links. LTP does Automatic
Repeat reQuest (ARQ) of data transmissions by soliciting selective-
acknowledgment reception reports. It is stateful and has no
negotiation or handshakes.
This document is a product of the Delay Tolerant Networking Research
Group and has been reviewed by that group. No objections to its
publication as an RFC were raised.
Burleigh, et al. Experimental [Page 1]
RFC 5325 LTP - Motivation September 2008
Table of Contents
1. Introduction ....................................................2
2. Problem .........................................................3
2.1. IPN Operating Environment ..................................3
2.2. Why Not TCP or SCTP? .......................................5
3. Protocol Overview ...............................................6
3.1. Nominal Operation ..........................................6
3.1.1. Link State Cues .....................................9
3.1.2. Deferred Transmission ...............................9
3.1.3. Timers .............................................10
3.2. Retransmission ............................................13
3.3. Accelerated Retransmission ................................16
3.4. Session Cancellation ......................................17
4. Security Considerations ........................................17
5. IANA Considerations ............................................20
6. Acknowledgments ................................................20
7. References .....................................................20
7.1. Informative References ....................................20
1. Introduction
The Licklider Transmission Protocol (LTP) is designed to provide
retransmission-based reliability over links characterized by
extremely long message round-trip times and/or frequent interruptions
in connectivity. Communication in interplanetary space is the most
prominent example of this sort of environment, and LTP is principally
aimed at supporting "long-haul" reliable transmission over deep-space
RF links. Specifically, LTP is intended to serve as a reliable
"convergence layer" protocol, underlying the Delay-Tolerant
Networking (DTN) [DTN] Bundle protocol [BP], in DTN deployments where
data links are characterized by very long round-trip times.
This document describes the motivation for LTP, its features,
functions, and overall design. It is part of a series of documents
describing LTP. Other documents in the series include the main
protocol specification document [LTPSPEC] and the protocol extensions
document [LTPEXT].
The protocol is named in honor of ARPA/Internet pioneer JCR
Licklider.
Burleigh, et al. Experimental [Page 2]
RFC 5325 LTP - Motivation September 2008
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