DTNMA Asynchronous Management Protocol (AMP)
draft-ietf-dtn-amp-00
| Document | Type | Active Internet-Draft (dtn WG) | |
|---|---|---|---|
| Authors | Edward J. Birrane , Brian Sipos | ||
| Last updated | 2024-11-06 | ||
| Replaces | draft-birrane-dtn-amp | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | (None) | ||
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| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Document | |
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draft-ietf-dtn-amp-00
Delay-Tolerant Networking E.J. Birrane
Internet-Draft B. Sipos
Intended status: Standards Track JHU/APL
Expires: 10 May 2025 6 November 2024
DTNMA Asynchronous Management Protocol (AMP)
draft-ietf-dtn-amp-00
Abstract
This document defines a messaging protocol for the Delay-Tolerant
Networking (DTN) Management Architecture (DTNMA) Asynchronous
Management Model (AMM) and a transport mapping for exchanging those
messages over a network. This Asynchronous Management Protocol (AMP)
does not require transport-layer sessions, operates over
unidirectional links, and seeks to reduce the energy and compute
power necessary for performing network management of resource
constrained devices and over challenged networks.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 10 May 2025.
Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Use of CDDL . . . . . . . . . . . . . . . . . . . . . . . 3
1.3. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. Constraints and Assumptions . . . . . . . . . . . . . . . . . 4
3. Message Structure and Sequencing . . . . . . . . . . . . . . 5
3.1. Execution-Set Values . . . . . . . . . . . . . . . . . . 6
3.2. Reporting-Set Values . . . . . . . . . . . . . . . . . . 6
4. Bundle Protocol Transport . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
5.1. URI Schemes . . . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . 9
Appendix A. Example Messages . . . . . . . . . . . . . . . . . . 10
Implementation Notes . . . . . . . . . . . . . . . . . . . . . . 11
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
Network management in challenged and resource constrained networks
must be accomplished differently than the network management methods
in low-delay, high-rate, high-availability networks. The Delay-
Tolerant Networking (DTN) Management Architecture (DTNMA), as defined
in [I-D.ietf-dtn-dtnma], provides an overview and justification of an
alternative to "synchronous" management services such as those
provided by SNMP [RFC3411] or NETCONF [RFC6241] (and its derivatives
RESTCONF [RFC8040] and CORECONF [I-D.ietf-core-comi]). In
particular, the DTNMA defines the need for a flexible, robust, and
efficient autonomy engine to handle decisions when operators cannot
be active in the network.
The logical description of that DTNMA Application Management Model
(AMM), and its realization in static Application Data Models (ADMs)
and dynamic Operational Data Models (ODMs), is in [I-D.ietf-dtn-amm].
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The AMM presents an efficient and expressive model for the
asynchronous management of a network node, but does not specify any
particular message structure or encoding.
This document, the DTNMA Asynchronous Management Protocol (AMP),
specifies an encoding of messages related to AMM objects using ARI
values [I-D.ietf-dtn-ari] as protocol data units (PDUs) in Section 3
and a transport of these PDUs within Bundle Protocol version 7 (BPv7)
[RFC9171] payloads in Section 4.
This AMP specification provides an enveloping of ARIs necessary to
support the AMM as described in Section 2.3 of [I-D.ietf-dtn-amm].
As such, AMP defines very few structures of its own.
1.1. Scope
The AMP provides data monitoring, administration, and configuration
for applications operating above the data link layer of the OSI
networking model. While the AMP may be configured to support the
management of network layer protocols, it also uses these protocol
stacks to encapsulate and communicate its own messages.
It is assumed that the transport(s) used to carry AMP messages
provide addressing, confidentiality, integrity, security,
fragmentation/reassembly, and other network functions. Therefore,
these items are outside of the scope of this document.
This document describes the format of messages used to exchange data
models between managing and managed devices in a network. The
rationale for this type of exchange is outside of the scope of this
document and is covered in [I-D.ietf-dtn-dtnma]. The description and
explanation of the data models exchanged is also outside of the scope
of this document and is covered in [I-D.ietf-dtn-amm].
This document does not address specific configurations of AMP-enabled
devices or any ADMs or ODMs available on such devices. This also
does not discuss the interface, if any, between AMP and other
management protocols.
1.2. Use of CDDL
This document defines Concise Binary Object Representation (CBOR)
structure using the Concise Data Definition Language (CDDL) of
[RFC8610]. The entire CDDL structure can be extracted from the XML
version of this document using the XPath expression:
'//sourcecode[@type="cddl"]'
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The following initial fragment defines the top-level symbols of this
document's CDDL, which includes the example CBOR content.
start = amp-adu
From the document [I-D.ietf-dtn-ari] the definitions are taken for
ari>, lit-execset, and lit-rptset.
1.3. Terminology
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 BCP 14 [RFC2119]
[RFC8174] when, and only when, they appear in all capitals, as shown
here.
The terms "Agent", "Application Data Model", "Externally Defined
Data", "Variable", "Control", "Literal", "Macro", "Manager", "Report
Template", "Report", "Table", "Constant", "Operator", "Time-Based
Rule" and "State-Based Rule" are used without modification from the
definitions provided in [I-D.ietf-dtn-amm].
2. Constraints and Assumptions
The desirable properties of an asynchronous management protocol, as
specified in the DTNMA, are summarized here to represent design
constraints on the AMP specification.
Intelligent Push of Information: Nodes in a challenged network
cannot guarantee concurrent, bi-directional communications. Some
links between nodes may be strictly unidirectional. In the DTNMA,
Agents "push" data to Managers rather than Managers "pulling" data
from Agents.
Small Message Sizes: Smaller messages require smaller periods of
viable transmission for communication, incur less retransmission
cost, and consume fewer resources when persistently stored en
route in the network. The AMP minimizes message size wherever
practical, to include binary data representations and predefined
data definitions and templates.
Static and Dynamic Identification: All data in the system must be
uniquely addressable, to include operator-specified information.
AMP provides a compact encoding for identifiers based on the
Application Resource Identifier (ARI) of [I-D.ietf-dtn-ari].
Stateless Operation: There is no reliable concept of session
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establishment or round-trip data exchange in challenged networks.
AMP is designed to be stateless and ADM controls are specified to
be idempotent when executed. Where helpful, AMP provides
mechanisms for ordering of execution within a single AMP protocol
data unit, but otherwise degrades gracefully when nodes in the
network diverge in their configuration.
Independence from ADMs: Although some portions of the AMP structure
share concepts and capabilities of AMM semantic types, the AMP
operates independently from any specific ADMs or ODMs which would
use the AMP for messaging between entities. This avoids the need
for an AMP processor to have information about those specific ADMs
or ODMs, similarly to how the ARI syntax processing is independent
from specific ADMs or ODMs. The interpreting of ARIs, however,
does require the use of specific referenced ADMs and ODMs.
All AMP encodings are self-terminating, based on Concise Binary
Object Representation (CBOR). This means that, given an indefinite-
length octet stream, each encoding can be unambiguously decoded from
the stream without requiring additional information such as a length
field separate from the data type definition. CBOR also provides a
layer of well-formed data coding separate from valid AMP structure
coding.
3. Message Structure and Sequencing
The function of the AMP is to deliver Execution-Set (EXECSET) and
Reporting-Set (RPTSET) values to a DTNMA Agent and a Manager
respectively. Together these support the needs described in
Section 2.3 of [I-D.ietf-dtn-amm].
Each AMP message consists of a version number followed by any number
of binary form ARI values, as defined in Section 5 of
[I-D.ietf-dtn-ari]. All AMP messages conforming to this
specification SHALL contain version number 1. Any AMP messages
received with an unknown version number SHALL be ignored.
Each of the contained ARIs SHALL be either an EXECSET or a RPTSET.
The EXECSET is used to communicate from Manager to Agent and cause
execution activities within the Agent as defined in Section 3.1. The
RPTSET is used to communicate from Agent to Manager, which includes
reports and (specific) execution results from the Agent, as defined
in Section 3.2.
Each AMP message has the following CDDL definition.
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amp-msg = [
version: 1,
*amp-ari
]
amp-ari = (lit-execset / lit-rptset) .within ari
3.1. Execution-Set Values
When received by an Agent, an EXECSET value SHALL result in immediate
execution activities based on the message contents. Each item in the
target list SHALL be executed independently (_i.e._, failures on one
item do not affect other items). Each item in the target list MAY be
executed in any order or concurrently. This is not the same behavior
as execution of a macro (see Section 6.6.3 of [I-D.ietf-dtn-amm]),
where execution of items is ordered and a failure of any execution
causes subsequent items to not be executed.
When possible, Managers SHOULD coalesce multiple execution targets
into a single EXECSET value. This avoids the overhead of processing
multiple messages on an Agent to cause multiple executions, but it
does require that all or none of the executions are associated with a
nonce value.
| Because execution targets are supposed to be idempotent (see
| Section 3.4.5 of [I-D.ietf-dtn-amm]) there is no need to
| differentiate multiple targets with the same object-identity-
| and-parameters when using the same nonce.
3.2. Reporting-Set Values
When received by a Manager, each report within a RPTSET value SHALL
be correlated to its ADM or ODM object used to interpret its source-
specific data. Each report in the Report List SHALL be processed
independently (_i.e._, failures on one report do not affect other
items). Each report in the Report List MAY be processed in any order
or concurrently.
When associated to the same nonce value, Agents SHOULD coalesce
multiple reports into a single RPTSET value. The coalescing MAY be
based on a time interval or an event (e.g. power-saving wake-up).
This avoids the overhead of processing multiple RPTSET values on a
Manager and improves timestamp compression in the items, but it does
require that all or none of the items are associated with the same
nonce value.
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4. Bundle Protocol Transport
When embedded as block type-specific data (BTSD) within a BPv7
payload block in accordance with [RFC9171], the application data unit
(ADU) SHALL consist of an AMP message (see Section 3) as a CBOR
sequence. The payload BTSD has the following CDDL definition.
amp-adu = bstr .cborseq amp-msg
When Agents and Managers register endpoints on a BPA, they SHOULD use
the well-known service numbers defined in Section 5.1. Using well-
known identifiers simplifies configuration and troubleshooting but is
not necessary for correct AMP operation.
When BPv7 is used as transport for AMP, the primary and payload
blocks SHALL be authenticated by a BPSec [RFC9172] mechanism
traceable to the message source. This can be either block integrity
block (BIB) or block confidentiality block (BCB) using an
authenticated encryption algorithm, either using an authenticated
public key of the source directly or via some security association
derived from an authenticated public key or from a security gateway
and delegated for the bundle source. It is an network policy and
configuration issue to determine the correct use of BPSec for any
particular Manager and Agent.
When processing an AMP ADU, the processing context SHALL include the
following:
* The bundle Source Node ID
* An indication of the authenticity of the primary and payload
blocks, along with the Security Source Node ID used to
authenticate them
5. IANA Considerations
This section provides guidance to the Internet Assigned Numbers
Authority (IANA) regarding registration of schema and namespaces
related to the Application Resource Identifier (ARI), in accordance
with BCP 26 [RFC1155].
5.1. URI Schemes
This document defines entries in the registry "'ipn' Scheme URI Well-
known Service Numbers for BPv7" within the "URI Schemes" registry
group [IANA-URI] containing the following.
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// RFC Editor: The values for TBA1 and TBA2 below should be assigned
// from the range 128-255.
+=========+==============+===========+
| Value | Description | Reference |
+=========+==============+===========+
| | DTNMA Agent | [This |
| // TBA1 | role | document] |
+---------+--------------+-----------+
| | DTNMA | [This |
| // TBA2 | Manager role | document] |
+---------+--------------+-----------+
Table 1: 'ipn' Scheme URI Well-
known Service Numbers for BPv7
6. Security Considerations
Security within the AMP exists in two distinct layers as follows:
Transport Security: Transport security addresses the questions of
authentication, integrity, and confidentiality associated with the
transport of messages between Managers and Agents. This security
is applied before any particular entity in the system receives
data and, therefore, its specifics are outside of the scope of
this document. The BP transport specified in Section 4 does
require some authentication which covers the AMP payload, but
details are network- and implementation-specific.
Access Control: Fine grained object-level security is provided and
enforced by Agents via access control lists (ACLs) which are part
of an Agent's configuration. An Agent's ACLs could be managed via
an ADM using AMP itself, but such details are also outside the
scope of this document.
7. References
7.1. Normative References
[IANA-URI] IANA, "Uniform Resource Identifier (URI) Schemes",
<https://www.iana.org/assignments/uri-schemes/>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
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[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC9171] Burleigh, S., Fall, K., and E. Birrane, III, "Bundle
Protocol Version 7", RFC 9171, DOI 10.17487/RFC9171,
January 2022, <https://www.rfc-editor.org/info/rfc9171>.
[RFC9172] Birrane, III, E. and K. McKeever, "Bundle Protocol
Security (BPSec)", RFC 9172, DOI 10.17487/RFC9172, January
2022, <https://www.rfc-editor.org/info/rfc9172>.
[I-D.ietf-dtn-amm]
Birrane, E. J., Sipos, B., and J. Ethier, "DTNMA
Application Management Model (AMM) and Data Models", Work
in Progress, Internet-Draft, draft-ietf-dtn-amm-01, 21
July 2024, <https://datatracker.ietf.org/doc/html/draft-
ietf-dtn-amm-01>.
[I-D.ietf-dtn-ari]
Birrane, E. J., Annis, E., and B. Sipos, "DTNMA
Application Resource Identifier (ARI)", Work in Progress,
Internet-Draft, draft-ietf-dtn-ari-02, 21 July 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-dtn-ari-
02>.
7.2. Informative References
[RFC1155] Rose, M. and K. McCloghrie, "Structure and identification
of management information for TCP/IP-based internets",
STD 16, RFC 1155, DOI 10.17487/RFC1155, May 1990,
<https://www.rfc-editor.org/info/rfc1155>.
[RFC3411] Harrington, D., Presuhn, R., and B. Wijnen, "An
Architecture for Describing Simple Network Management
Protocol (SNMP) Management Frameworks", STD 62, RFC 3411,
DOI 10.17487/RFC3411, December 2002,
<https://www.rfc-editor.org/info/rfc3411>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/info/rfc6241>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
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[RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
Definition Language (CDDL): A Notational Convention to
Express Concise Binary Object Representation (CBOR) and
JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
June 2019, <https://www.rfc-editor.org/info/rfc8610>.
[I-D.ietf-core-comi]
Veillette, M., Van der Stok, P., Pelov, A., Bierman, A.,
and C. Bormann, "CoAP Management Interface (CORECONF)",
Work in Progress, Internet-Draft, draft-ietf-core-comi-19,
3 November 2024, <https://datatracker.ietf.org/doc/html/
draft-ietf-core-comi-19>.
[I-D.ietf-dtn-dtnma]
Birrane, E. J., Heiner, S., and E. Annis, "DTN Management
Architecture", Work in Progress, Internet-Draft, draft-
ietf-dtn-dtnma-14, 28 April 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-dtn-
dtnma-14>.
Appendix A. Example Messages
An example of an Execution-Set being sent to an Agent has the
following ARI text representation.
ari:/EXECSET/n=1234;(//example-adm-a/CTRL/dothing,//example-adm-a/CONST/amacro)
Assuming some enumeration values for the ADM and objects results in
the following transformed ARI.
ari:/EXECSET/n=1234;(//65536/-3/18,//65536/-2/43)
This is embedded into an AMP message with the following CBOR
sequence.
1,
[20, [1234, [65536, -3, 18], [65536, -2, 43]]]
Which is encoded to the following binary string.
0x018214831904D2831A000100002212831A0001000021182B
An example of a corresponding Reporting-Set being sent to a Manager
has the following ARI text representation.
ari:/RPTSET/n=1234;r=/TP/20230102T030405Z;(t=/TD/PT0S;s=//example-adm-a/CTRL/dothing;(null))(t=/TD/PT5S;s=//example-adm-a/CTRL/other;(567))
Which results in the following transformed ARI.
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ari:/RPTSET/n=1234;r=/TP/725943845;(t=/TD/0;s=//65536/-3/18;(null))(t=/TD/5;s=//65536/-3/6;(567)))
This is embedded into an AMP message with the following CBOR
sequence.
1,
[21, 1234, 725943845, [0, [65536, -3, 18], null], [5, [65536, -3, 6], 567]]
Which is encoded to the following binary string.
0x0185151904D21A2B4506258300831A000100002212F68305831A000100002206190237
Implementation Notes
This section is to be removed before publishing as an RFC.
A reference implementation of an earlier revision of the AMP is
available in the 3.6.2 release of the ION open source code base
available from the ION-DTN (https://sourceforge.net/projects/ion-
dtn/) Sourceforge project.
An extraction of the same AMP Agent and Manager from ION into a
stand-alone project is available in the DTNMA Tools
(https://github.com/JHUAPL/dtnma-tools) GitHub project. This project
also contains an updated Wireshark AMP dissector
(https://github.com/JHUAPL/dtnma-tools/tree/main/wireshark) for the
corresponding earlier revision of this draft.
Acknowledgments
The following participants contributed technical material, use cases,
and useful thoughts on the overall approach to this protocol
specification: Jeremy Pierce-Mayer of INSYEN AG contributed the
concept of the typed data collection and early type checking in the
protocol. David Linko and Evana DiPietro of the Johns Hopkins
University Applied Physics Laboratory contributed appreciated review
and type checking of various elements of this specification.
Authors' Addresses
Edward J. Birrane, III
The Johns Hopkins University Applied Physics Laboratory
11100 Johns Hopkins Rd.
Laurel, MD 20723
United States of America
Phone: +1 443 778 7423
Email: Edward.Birrane@jhuapl.edu
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Brian Sipos
The Johns Hopkins University Applied Physics Laboratory
Email: brian.sipos+ietf@gmail.com
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