Internet DRAFT - draft-bw-alto-cost-mode
draft-bw-alto-cost-mode
alto M. Boucadair
Internet-Draft Orange
Updates: 7285 (if approved) Q. Wu
Intended status: Standards Track Huawei
Expires: 5 September 2022 4 March 2022
A Cost Mode Registry for the Application-Layer Traffic Optimization
(ALTO) Protocol
draft-bw-alto-cost-mode-01
Abstract
This document creates a new IANA registry for tracking cost modes
supported by the Application-Layer Traffic Optimization (ALTO)
protocol. Also, this document relaxes a constraint that was imposed
by the ALTO specification on allowed cost mode values.
This document updates RFC 7285.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 5 September 2022.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Updates to RFC7285 . . . . . . . . . . . . . . . . . . . . . 3
3.1. Update to Section 6.1.2 of RFC7285 . . . . . . . . . . . 3
3.2. Update to Section 10.5 of RFC7285 . . . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
7.1. Normative References . . . . . . . . . . . . . . . . . . 4
7.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
The cost mode attribute indicates how costs should be interpreted
when communicated in the Application-Layer Traffic Optimization
(ALTO) protocol [RFC7285]. The base ALTO specification includes a
provision for only two modes:
"numerical": Indicates that numerical operations can be performed
(e.g., normalization) on the returned costs (Section 6.1.2.1 of
[RFC7285]).
"ordinal": Indicates that the cost values in a cost map represent
ranking (relative to all other values in a cost map), not actual
costs (Section 6.1.2.2 of [RFC7285]).
Additional cost modes are required for specific ALTO deployment cases
(e.g., [I-D.ietf-alto-path-vector]). In order to allow for such use
cases, this document creates a new ALTO registry to track new cost
mode values (Section 4) and relaxes the constraints imposed by the
base ALTO specification on allowed cost mode values (Section 3).
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2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "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.
This document makes use of the terms defined in [RFC7285].
3. Updates to RFC7285
3.1. Update to Section 6.1.2 of RFC7285
This document updates Section 6.1.2 of [RFC7285] as follows:
OLD:
The cost mode attribute indicates how costs should be interpreted.
Specifically, the cost mode attribute indicates whether returned
costs should be interpreted as numerical values or ordinal rankings.
It is important to communicate such information to ALTO clients, as
certain operations may not be valid on certain costs returned by an
ALTO server. For example, it is possible for an ALTO server to
return a set of IP addresses with costs indicating a ranking of the
IP addresses. Arithmetic operations that would make sense for
numerical values, do not make sense for ordinal rankings. ALTO
clients may handle such costs differently.
Cost modes are indicated in protocol messages as strings.
NEW:
The cost mode attribute indicates how costs should be interpreted.
This document defines two cost modes (numerical values or ordinal
rankings), but additional values can be defined in the future.
It is important to communicate such information to ALTO clients, as
certain operations may not be valid on certain costs returned by an
ALTO server. For example, it is possible for an ALTO server to
return a set of IP addresses with costs indicating a ranking of the
IP addresses. Arithmetic operations that would make sense for
numerical values, do not make sense for ordinal rankings. ALTO
clients may handle such costs differently.
Cost modes are indicated in protocol messages as strings.
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3.2. Update to Section 10.5 of RFC7285
This document updates Section 10.5 of [RFC7285] as follows:
OLD:
A cost mode is encoded as a string. The string MUST have a value of
either "numerical" or "ordinal".
NEW:
A cost mode is encoded as a string. The string MUST have a value
that is listed in the registry created in Section 4 of RFCXXXX.
* Note to the RFC Editor: Please replace RFCXXXX with the RFC number
to be assigned to this document.
4. IANA Considerations
This document requests IANA to create a new subregistry entitled
"ALTO Cost Modes" under the "Application-Layer Traffic Optimization
(ALTO) Protocol" registry available at [ALTO].
The registry is initially populated with the following values:
+-------------+-----------------------------+
| Cost Mode | Specification |
+-------------+-----------------------------+
| numerical | Section 6.1.2.1 of RFC7285 |
| ordinal | Section 6.1.2.2 of RFC7285 |
+-------------+-----------------------------+
New values MUST be assigned after IETF Review (Section 4.8 of
[RFC8126]).
5. Security Considerations
ALTO-related considerations are discussed in Section 15 of [RFC7285].
6. Acknowledgements
Many thanks to Benjamin Kaduk for spotting the issue during the
review of [I-D.ietf-alto-path-vector].
7. References
7.1. Normative References
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[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>.
[RFC7285] Alimi, R., Ed., Penno, R., Ed., Yang, Y., Ed., Kiesel, S.,
Previdi, S., Roome, W., Shalunov, S., and R. Woundy,
"Application-Layer Traffic Optimization (ALTO) Protocol",
RFC 7285, DOI 10.17487/RFC7285, September 2014,
<https://www.rfc-editor.org/info/rfc7285>.
[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>.
7.2. Informative References
[ALTO] "Application-Layer Traffic Optimization (ALTO) Protocol",
2 March 2022, <https://www.iana.org/assignments/alto-
protocol/alto-protocol.xhtml>.
[I-D.ietf-alto-path-vector]
Gao, K., Lee, Y., Randriamasy, S., Yang, Y. R., and J. J.
Zhang, "An ALTO Extension: Path Vector", Work in Progress,
Internet-Draft, draft-ietf-alto-path-vector-22, 25
February 2022, <https://www.ietf.org/archive/id/draft-
ietf-alto-path-vector-22.txt>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
Authors' Addresses
Mohamed Boucadair
Orange
35000 Rennes
France
Email: mohamed.boucadair@orange.com
Qin Wu
Huawei
101 Software Avenue, Yuhua District
Nanjing
Jiangsu, 210012
China
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Email: bill.wu@huawei.com
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