Network Working Group V. Cerf Request for Comments: 4838 Google/Jet Propulsion Laboratory Category: Informational S. Burleigh A. Hooke L. Torgerson NASA/Jet Propulsion Laboratory R. Durst K. Scott The MITRE Corporation K. Fall Intel Corporation H. Weiss SPARTA, Inc. April 2007 Delay-Tolerant Networking Architecture
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.
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Copyright (C) The IETF Trust (2007).
IESG Note
This RFC is a product of the Internet Rearch Task Force and is not a candidate for any level of Internet Standard. The IRTF publishes
the results of Internet-related rearch and development activities. The results might not be suitable for deployment on the public
Internet.
Abstract
This document describes an architecture for delay-tolerant and
disruption-tolerant networks, and is an evolution of the architecture originally designed for the Interplanetary Internet, a communication system envisioned to provide Internet-like rvices across
interplanetary distances in support of deep space exploration. This document describes an architecture that address a variety of
problems with internetworks having operational and performance
characteristics that make conventional (Internet-like) networking
approaches either unworkable or impractical. We define a message-
oriented overlay that exists above the transport (or other) layers of Cerf, et al. Informational [Page 1]
the networks it interconnects. The document prents a motivationdell客服
for the architecture, an architectural overview, review of state
management required for its operation, and a discussion of魏长亮
application design issues. This document reprents the connsus of the IRTF DTN rearch group and has been widely reviewed by that
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group.
Table of Contents
1. Introduction (3)
2. Why an Architecture for Delay-Tolerant Networking? (4)
3. DTN Architectural Description (5)
3.1. Virtual Message Switching Using Store-and-Forward
Operation (5)
3.2. Nodes and Endpoints (7)
3.3. Endpoint Identifiers (EIDs) and Registrations (8)
3.4. Anycast and Multicast (10)
3.5. Priority Class (10)
3.6. Postal-Style Delivery Options and Administrative Records ..11 3.7. Primary Bundle Fields (15)
3.8. Routing and Forwarding (16)
3.9. Fragmentation and Reasmbly (18)
3.10. Reliability and Custody Transfer (19)
我们曾经在一起3.11. DTN Support for Proxies and Application Layer Gateways (21)
3.12. Timestamps and Time Synchronization (22)
3.13. Congestion and Flow Control at the Bundle Layer (22)
3.14. Security (23)
4. State Management Considerations (25)
4.1. Application Registration State (25)
4.2. Custody Transfer State (26)
4.3. Bundle Routing and Forwarding State (26)
4.4. Security-Related State (27)
4.5. Policy and Configuration State (27)
5. Application Structuring Issues (28)同胞
6. Convergence Layer Considerations for U of Underlying
Protocols (28)
7. Summary (29)
8. Security Considerations (29)
9. IANA Considerations (30)
10. Normative References (30)
11. Informative References (30)
12. Acknowledgments (32)
Cerf, et al. Informational [Page 2]
1. Introduction
This document describes an architecture for delay and disruption-
tolerant interoperable networking (DTN). The architecture embraces
the concepts of occasionally-connected networks that may suffer from frequent partitions and that may be comprid of more than one
divergent t of protocols or protocol families. The basis for this architecture lies with that of the Interplanetary Internet, which
focud primarily on the issue of deep space communication in high-
delay environments. We expect the DTN architecture described here to be utilized in various operational environments, including tho
subject to disruption and disconnection and tho with high-delay;
the ca of deep space is one specialized example of the, and is
being pursued as a specialization of this architecture (See [IPN01]
and [SB03] for more details).
Other networks to which we believe this architecture applies include nsor-bad networks using scheduled intermittent connectivity,
terrestrial wireless networks that cannot ordinarily maintain end-to- end connectivity, satellite networks with moderate delays and
periodic connectivity, and underwater acoustic networks with moderate delays and frequent interruptions due to environmental factors. A
DTN tutorial [FW03], aimed at introducing DTN and the types of
networks for which it is designed, is available to introduce new
readers to the fundamental concepts and motivation. More technical
descriptions may be found in [KF03], [JFP04], [JDPF05], and [WJMF05]. We define an end-to-end message-oriented overlay called the "bundle长白山北坡
layer" that exists at a layer above the transport (or other) layers
of the networks on which it is hosted and below applications.
Devices implementing the bundle layer are called DTN nodes. The
bundle layer forms an overlay that employs persistent storage to help combat network interruption. It includes a hop-by-hop transfer of
reliable delivery responsibility and optional end-to-end
acknowledgement. It also includes a number of diagnostic and
management features. For interoperability, it us a flexible naming scheme (bad on Uniform Resource Identifiers [RFC3986]) capable of
encapsulating different naming and addressing schemes in the same
overall naming syntax. It also has a basic curity model,
optionally enabled, aimed at protecting infrastructure from
unauthorized u.
The bundle layer provides functionality similar to the internet layer of gateways described in the original ARPANET/Internet designs
[CK74]. It differs from ARPANET gateways, however, becau it is
layer-agnostic and is focud on virtual message forwarding rather
than packet switching. However, both generally provide
interoperability between underlying protocols specific to one
Cerf, et al. Informational [Page 3]
environment and tho protocols specific to another, and both provide a store-and-forward forwarding rvice (with the bundle layer
employing persistent storage for its store and forward function).
In a n, the DTN architecture provides a common method for
interconnecting heterogeneous gateways or proxies that employ store- and-forward message routing to overcome communication disruptions.
It provides rvices similar to electronic mail, but with enhanced
naming, routing, and curity capabilities. Nodes unable to support the full capabilities required by this architecture may be supported by application-layer proxies acting as DTN applications.
2. Why an Architecture for Delay-Tolerant Networking?
Our motivation for pursuing an architecture for delay tolerant
networking stems from veral factors. The factors are summarized below; much more detail on their rationale can be explored in [SB03], [KF03], and [DFS02].
The existing Internet protocols do not work well for some
environments, due to some fundamental assumptions built into the
Internet architecture:
-
that an end-to-end path between source and destination exists for
the duration of a communication ssion
- (for reliable communication) that retransmissions bad on timely
and stable feedback from data receivers is an effective means for
repairing errors
- that end-to-end loss is relatively small
- that all routers and end stations support the TCP/IP protocols
- that applications need not worry about communication performance
- that endpoint-bad curity mechanisms are sufficient for meeting most curity concerns
- that packet switching is the most appropriate abstraction for
interoperability and performance
-
that lecting a single route between nder and receiver is
sufficient for achieving acceptable communication performance
The DTN architecture is conceived to relax most of the assumptions, bad on a number of design principles that are summarized here (and further discusd in [KF03]):
Cerf, et al. Informational [Page 4]
- U variable-length (possibly long) messages (not streams or
limited-sized packets) as the communication abstraction to help
enhance the ability of the network to make good scheduling/path
lection decisions when possible.
- U a naming syntax that supports a wide range of naming and
addressing conventions to enhance interoperability.
- U storage within the network to support store-and-forward
operation over multiple paths, and over potentially long timescales (i.e., to support operation in environments where many and/or no
end-to-end paths may ever exist); do not require end-to-end
reliability.
- Provide curity mechanisms that protect the infrastructure from
unauthorized u by discarding traffic as quickly as possible.豆腐鱼的做法
- Provide coar-grained class of rvice, delivery options, and a way to express the uful lifetime of data to allow the network to better deliver data in rving the needs of applications.
The u of the bundle layer is guided not only by its own design
principles, but also by a few application design principles:
- Applications should minimize the number of round-trip exchanges.
- Applications should cope with restarts after failure while network transactions remain pending.
- Applications should inform the network of the uful life and
relative importance of data to be delivered.
The issues are discusd in further detail in Section 5.
3. DTN Architectural Description
The previous ction summarized the design principles that guide the definition of the DTN architecture. This ction prents a
description of the major features of the architecture resulting from design decisions guided by the aforementioned design principles.
3.1. Virtual Message Switching Using Store-and-Forward Operation
A DTN-enabled application nds messages of arbitrary length, also
called Application Data Units or ADUs [CT90], which are subject to
any implementation limitations. The relative order of ADUs might not be prerved. ADUs are typi
cally nt by and delivered to
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