rfc9894.original   rfc9894.txt 
MANET B. Cheng Internet Engineering Task Force (IETF) B. Cheng
Internet-Draft MIT Lincoln Laboratory Request for Comments: 9894 MIT Lincoln Laboratory
Intended status: Standards Track D. Wiggins Category: Standards Track D. Wiggins
Expires: 4 September 2025 ISSN: 2070-1721
L. Berger L. Berger
LabN Consulting, L.L.C. LabN Consulting, L.L.C.
D. Eastlake, Ed. D. Eastlake 3rd, Ed.
Independent Independent
3 March 2025 November 2025
DLEP DiffServ Aware Credit Window Extension Dynamic Link Exchange Protocol (DLEP) Diffserv Aware Credit Window
draft-ietf-manet-dlep-da-credit-extension-21 Extension
Abstract Abstract
This document defines an extension to the Dynamic Link Exchange This document defines an extension to the Dynamic Link Exchange
Protocol (DLEP) that enables a DiffServ aware credit-window scheme Protocol (DLEP) that enables a Diffserv aware credit-window scheme
for destination-specific and shared flow control. for destination-specific and shared flow control.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on 4 September 2025. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9894.
Copyright Notice Copyright Notice
Copyright (c) 2025 IETF Trust and the persons identified as the Copyright (c) 2025 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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in the Revised BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction
1.1. Key Words . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Key Words
2. Extension Usage and Identification . . . . . . . . . . . . . 3 2. Extension Usage and Identification
3. Management Considerations . . . . . . . . . . . . . . . . . . 4 3. Management Considerations
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4 4. Security Considerations
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 5. IANA Considerations
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 6. References
6.1. Normative References . . . . . . . . . . . . . . . . . . 5 6.1. Normative References
6.2. Informative References . . . . . . . . . . . . . . . . . 6 6.2. Informative References
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 6 Acknowledgments
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses
1. Introduction 1. Introduction
The Dynamic Link Exchange Protocol (DLEP) is defined in [RFC8175]. The Dynamic Link Exchange Protocol (DLEP) is defined in [RFC8175].
The protocol provides the exchange of link related control The protocol provides the exchange of link-related control
information between DLEP peers. DLEP peers consist of a modem and a information between DLEP peers. DLEP peers consist of a modem and a
router. DLEP defines a base set of mechanisms as well as support for router. DLEP defines a base set of mechanisms as well as support for
possible extensions. This document defines one such extension. possible extensions. This document defines one such extension.
The DLEP specification does not include any flow control capability. The DLEP specification does not include any flow control capability.
There are various flow control techniques theoretically possible with Various flow control techniques are theoretically possible with DLEP.
DLEP. This document defines a DLEP extension which provides a This document defines a DLEP extension that provides a Diffserv-based
DiffServ-based flow control mechanism for traffic sent from a router flow control mechanism for traffic sent from a router to a modem.
to a modem. Flow control is provided using one or more logical Flow control is provided using one or more logical "Credit Windows",
"Credit Windows", each of which will typically be supported by an each of which will typically be supported by an associated virtual or
associated virtual or physical queue. A router will use traffic flow physical queue. A router will use traffic flow classification
classification information provided by the modem to identify which information provided by the modem to identify which traffic is
traffic is associated with each credit window. Credit windows may be associated with each credit window. Credit windows may be shared or
shared or dedicated on a per-flow basis. See dedicated on a per-flow basis. See [RFC9895] for an Ethernet-based
[I-D.ietf-manet-dlep-ether-credit-extension] for an Ethernet-based
version of credit window flow control. As specified in Section 2.3.1 version of credit window flow control. As specified in Section 2.3.1
of [I-D.ietf-manet-dlep-traffic-classification], when both DiffServ of [RFC9892], when both Diffserv and Ethernet traffic classification
and Ethernet traffic classification are specified for a flow, the are specified for a flow, the Ethernet information takes precedence.
Ethernet information takes precedence.
This document uses the traffic classification and credit window This document uses the traffic classification and credit window
control mechanisms defined in control mechanisms defined in [RFC9892] and [RFC9893] to provide
[I-D.ietf-manet-dlep-traffic-classification] and credit-window-based flow control based on DLEP destinations and
[I-D.ietf-manet-dlep-credit-flow-control] to provide credit window Differentiated Services Code Points (DSCPs) [RFC2475]. The defined
based flow control based on DLEP destinations and DiffServ [RFC2475] mechanism allows for credit windows to be shared across traffic sent
DSCPs (differentiated services codepoints). The defined mechanism to multiple DLEP destinations and DSCPs, or used exclusively for
allows for credit windows to be shared across traffic sent to traffic sent to a particular destination and/or DSCP. The extension
multiple DLEP destinations and DSCPs, or used exclusively for traffic also supports the "wildcard" matching of any DSCP.
sent to a particular destination and/or DSCP. The extension also
supports the "wildcard" matching of any DSCP.
The extension defined in this document is referred to as "DiffServ The extension defined in this document is referred to as the
Aware Credit Window" or, more simply, the "DA Credit" extension. The "Diffserv Aware Credit Window" or, more simply, the "DA Credit"
reader should be familiar with both the traffic classification and extension. The reader should be familiar with both the traffic
credit window control mechanisms defined in classification and credit window control mechanisms defined in
[I-D.ietf-manet-dlep-traffic-classification] and [RFC9892] and [RFC9893].
[I-D.ietf-manet-dlep-credit-flow-control].
This document defines a new DLEP Extension Type Value in Section 2 This document defines a new DLEP Extension Type Value that is used to
which is used to indicate support for the extension. indicate support for the extension. See Section 2.
1.1. Key Words 1.1. Key Words
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2. Extension Usage and Identification 2. Extension Usage and Identification
The extension defined in this document is composed of the mechanisms The extension defined in this document is composed of the mechanisms
and processing defined in and processing defined in [RFC9892] and [RFC9893]. To indicate that
[I-D.ietf-manet-dlep-traffic-classification] and the Diffserv Aware Credit Window Extension is to be used, an
[I-D.ietf-manet-dlep-credit-flow-control]. To indicate that the implementation MUST include the Diffserv Aware Credit Window Type
DiffServ Aware Credit Window Extension is to be used, an
implementation MUST include the DiffServ Aware Credit Window Type
Value in the Extensions Supported Data Item (see Section 13.6 of Value in the Extensions Supported Data Item (see Section 13.6 of
[RFC8175]). The Extensions Supported Data Item is sent and processed [RFC8175]). The Extensions Supported Data Item is sent and processed
according to [RFC8175]. Any implementation that indicates use of the according to [RFC8175]. Any implementation that indicates the use of
DiffServ Aware Credit Window Extension MUST support all Messages, the Diffserv Aware Credit Window Extension MUST support all message
Data Items, the DiffServ Traffic Classification Sub-Data Item, and types, Data Items, the Diffserv Traffic Classification Sub-Data Item,
all related processing defined in and all related processing defined in [RFC9892] and [RFC9893].
[I-D.ietf-manet-dlep-traffic-classification] and
[I-D.ietf-manet-dlep-credit-flow-control].
The DiffServ Aware Credit Window Extension Type Value is TBA1, see The Diffserv Aware Credit Window Extension Type Value is 6. See
Section 5. Section 5.
3. Management Considerations 3. Management Considerations
This section provides several network management guidelines to This section provides several network management guidelines for
implementations supporting the DiffServ Aware Credit Window implementations supporting the Diffserv Aware Credit Window
Extension. Extension.
If this extension is supported, that support MUST be declared using If this extension is supported, that support MUST be declared using
the Extensions Supported Data Item (see Section 13.6 of [RFC8175]). the Extensions Supported Data Item (see Section 13.6 of [RFC8175]).
DiffServ Aware Credit Window Extension Data Items MUST NOT be emitted Diffserv Aware Credit Window Extension Data Items MUST NOT be emitted
by a DLEP participant unless such support was specified in the by a DLEP participant unless such support was specified in the
initialization message received from its peer. The use of the initialization message received from its peer. The use of the
extension defined in this document SHOULD be configurable on both extension defined in this document SHOULD be configurable on both
modems and routers. That configuration can be implemented using a modems and routers. That configuration can be implemented using a
proprietary CLI or by implementing a YANG module. The definition of proprietary Command-Line Interface (CLI) or by implementing a YANG
the YANG module is out of the scope of this document. module. The definition of the YANG module is out of scope for this
document.
Modems SHOULD support the configuration of DSCP to credit window Modems SHOULD support the configuration of mapping a DSCP to a credit
(queue) mapping. window (queue).
Modems MAY support the configuration of the number of credit windows Modems MAY support the configuration of the number of credit windows
(queues) to advertise to a router. (queues) to advertise to a router.
Routers may have limits on the number of queues that they can support Routers may have limits on the number of queues that they can support
and limits on supported credit window combinations. Per destination and limits on supported credit window combinations. Per-destination
queues might not be supported at all. When modem-provided credit queues might not be supported at all. When credit window information
window information exceeds the capabilities of a router, the router provided by a modem exceeds the capabilities of a router, the router
SHOULD use a subset of the provided credit windows. Alternatively, a SHOULD use a subset of the provided credit windows. Alternatively, a
router MAY reset the session and indicate that the extension is not router MAY reset the session and indicate that the extension is not
supported. In either case, the mismatch of capabilities SHOULD be supported. In either case, any mismatch in capabilities SHOULD be
reported to the user via normal network management mechanisms such as reported to the user via normal network management mechanisms, such
user interface messages or error logging. as user interface messages or error logging.
In all cases, if credit windows are in use, traffic for which credits In all cases, if credit windows are in use, traffic for which credits
are not available MUST NOT be sent to the modem by the router. are not available MUST NOT be sent to the modem by the router.
4. Security Considerations 4. Security Considerations
This document defines a DLEP extension that uses DLEP mechanisms and This document defines a DLEP extension that uses DLEP mechanisms and
the credit window control and flow mechanisms defined in the credit window control and flow mechanisms defined in [RFC9892]
[I-D.ietf-manet-dlep-traffic-classification] and and [RFC9893]. See also the Security Considerations sections of
[I-D.ietf-manet-dlep-credit-flow-control]. See also the Security those documents.
Considerations sections of those documents.
The defined extension is exposed to vulnerabilities similar to The defined extension is exposed to vulnerabilities similar to
existing DLEP messages and discussed in the Security Considerations existing DLEP messages and discussed in the Security Considerations
section of [RFC8175] such as an injected message resizing a credit section of [RFC8175], such as an injected message resizing a credit
window to a value that results in a denial of service. The security window to a value that results in a denial of service. The security
mechanisms documented in [RFC8175] can be applied equally to the mechanisms documented in [RFC8175] can be applied equally to the
mechanism defined in this document. mechanism defined in this document.
Wildcards for matching Priority Code point (PCP) and VLAN ID (VID) Wildcards for matching Priority Code Point (PCP) and VLAN Identifier
fields (see [I-D.ietf-manet-dlep-ether-credit-extension]) are (VID) fields (see [RFC9895]) are provided. Note that wildcards may
provided which may be convenient to match a number of packet flows be convenient for matching a number of packet flows but could
but could inadvertently match unexpected flows or new flows that inadvertently match unexpected flows or new flows that appear after
appear after the wildcard matching has been set up. It is therefore the wildcard matching has been set up. It is therefore RECOMMENDED
RECOMMENDED that wildcards not be used unless needed. that wildcards not be used unless needed.
5. IANA Considerations 5. IANA Considerations
IANA is requested to assign one code point in the "Extension Type IANA has assigned the following code point in the "Extension Type
Values" registry in the "Dynamic Link Exchange Protocol (DLEP) Values" registry in the "Dynamic Link Exchange Protocol (DLEP)
Parameters" registry group as follows: Parameters" registry group:
+======+==============================+ +======+==============================+
| Code | Description | | Code | Description |
+======+==============================+ +======+==============================+
| TBA1 | DiffServ Aware Credit Window | | 6 | Diffserv Aware Credit Window |
+------+------------------------------+ +------+------------------------------+
Table 1: Requested Extension Type Value Table 1: Extension Type Value
6. References 6. References
6.1. Normative References 6.1. Normative References
[I-D.ietf-manet-dlep-credit-flow-control]
Cheng, B., Wiggins, D., Berger, L., Ratliff, S., and E.
Kinzie, "Dynamic Link Exchange Protocol (DLEP) Credit-
Based Flow Control Messages and Data Items", Work in
Progress, Internet-Draft, draft-ietf-manet-dlep-credit-
flow-control, 3 January 2025,
<https://datatracker.ietf.org/doc/draft-ietf-manet-dlep-
credit-flow-control>.
[I-D.ietf-manet-dlep-traffic-classification]
Cheng, B., Wiggins, D., Berger, L., and D. Fedyk, "Dynamic
Link Exchange Protocol (DLEP) Traffic Classification Data
Item", Work in Progress, Internet-Draft, draft-ietf-manet-
dlep-traffic-classification, 19 November 2024,
<https://datatracker.ietf.org/doc/draft-ietf-manet-dlep-
traffic-classification>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8175] Ratliff, S., Jury, S., Satterwhite, D., Taylor, R., and B. [RFC8175] Ratliff, S., Jury, S., Satterwhite, D., Taylor, R., and B.
Berry, "Dynamic Link Exchange Protocol (DLEP)", RFC 8175, Berry, "Dynamic Link Exchange Protocol (DLEP)", RFC 8175,
DOI 10.17487/RFC8175, June 2017, DOI 10.17487/RFC8175, June 2017,
<https://www.rfc-editor.org/info/rfc8175>. <https://www.rfc-editor.org/info/rfc8175>.
6.2. Informative References [RFC9892] Cheng, B., Wiggins, D., Berger, L., and D. Fedyk, Ed.,
"Dynamic Link Exchange Protocol (DLEP) Traffic
Classification Data Item", RFC 9892, DOI 10.17487/RFC9892,
November 2025, <https://www.rfc-editor.org/info/rfc9892>.
[I-D.ietf-manet-dlep-ether-credit-extension] [RFC9893] Cheng, B., Wiggins, D., Ratliff, S., Berger, L., and E.
Wiggins, D., Berger, L., and D. E. Eastlake, "DLEP IEEE Kinzie, Ed., "Dynamic Link Exchange Protocol (DLEP)
802.1Q Aware Credit Window Extension", Work in Progress, Credit-Based Flow Control Messages and Data Items",
Internet-Draft, draft-ietf-manet-dlep-ether-credit- RFC 9893, DOI 10.17487/RFC9893, November 2025,
extension, 15 December 2024, <https://www.rfc-editor.org/info/rfc9893>.
<https://datatracker.ietf.org/doc/draft-ietf-manet-dlep-
ether-credit-extension/>. 6.2. Informative References
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z., [RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
and W. Weiss, "An Architecture for Differentiated and W. Weiss, "An Architecture for Differentiated
Services", RFC 2475, DOI 10.17487/RFC2475, December 1998, Services", RFC 2475, DOI 10.17487/RFC2475, December 1998,
<https://www.rfc-editor.org/info/rfc2475>. <https://www.rfc-editor.org/info/rfc2475>.
Appendix A. Acknowledgments [RFC9895] Wiggins, D., Berger, L., and D. Eastlake 3rd, Ed.,
"Dynamic Link Exchange Protocol (DLEP) IEEE 802.1Q Aware
Credit Window Extension", RFC 9895, DOI 10.17487/RFC9895,
November 2025, <https://www.rfc-editor.org/info/rfc9895>.
The Sub-Data item format was inspired by Rick Taylor's "Data Item Acknowledgments
The Sub-Data Item format was inspired by Rick Taylor's "Data Item
Containers". He also proposed the separation of credit windows from Containers". He also proposed the separation of credit windows from
traffic classification at IETF 98. Many useful comments were traffic classification at IETF 98. Many useful comments were
received from contributors to the MANET working group, notably Ronald received from contributors to the MANET Working Group, notably Ronald
in't Velt. in 't Velt.
We had the honor of working too briefly with David Wiggins on this We had the honor of working too briefly with David Wiggins on this
and related DLEP work. His contribution to the IETF and publication and related DLEP work. His contribution to the IETF and publication
of the first and definitive open source DLEP implementation have been of the first and definitive open-source DLEP implementation have been
critical to the acceptance of DLEP. We mourn his passing on November critical to the acceptance of DLEP. We mourn his passing on November
23, 2023. We wish to recognize his guidance, leadership and 26, 2023. We wish to recognize his guidance, leadership, and
professional excellence. We were fortunate to benefit from his professional excellence. We were fortunate to benefit from his
leadership and friendship. He shall be missed. leadership and friendship. He shall be missed.
Authors' Addresses Authors' Addresses
Bow-Nan Cheng Bow-Nan Cheng
MIT Lincoln Laboratory MIT Lincoln Laboratory
Massachusetts Institute of Technology Massachusetts Institute of Technology
244 Wood Street 244 Wood Street
Lexington Lexington, MA 02421-6426
United States of America
Email: bcheng@ll.mit.edu Email: bcheng@ll.mit.edu
David Wiggins David Wiggins
Email: david@none.org
Lou Berger Lou Berger
LabN Consulting, L.L.C. LabN Consulting, L.L.C.
Email: lberger@labn.net Email: lberger@labn.net
Donald E. Eastlake 3rd (editor) Donald E. Eastlake 3rd (editor)
Independent Independent
2386 Panoramic Circle 2386 Panoramic Circle
Apopka, Florida 32703 Apopka, FL 32703
United States of America United States of America
Phone: +1-508-333-2270 Phone: +1-508-333-2270
Email: d3e3e3@gmail.com Email: d3e3e3@gmail.com
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