Network Working Group B. Cheng
Internet-Draft D. Wiggins
Intended status: Standards Track Lincoln Laboratory
Expires: November 2, 2018 L. Berger
LabN Consulting, L.L.C.
May 1, 2018
DLEP DiffServ Aware Credit Window Extension
draft-ietf-manet-dlep-da-credit-extension-05
Abstract
This document defines an extension to the DLEP protocol that enables
a DiffServ aware credit-window scheme for destination-specific and
shared flow control.
Status of This Memo
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This Internet-Draft will expire on November 2, 2018.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Key Words . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Extension Usage and Identification . . . . . . . . . . . . . 3
3. Management Considerations . . . . . . . . . . . . . . . . . . 3
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
5.1. Extension Type Value . . . . . . . . . . . . . . . . . . 4
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
6.1. Normative References . . . . . . . . . . . . . . . . . . 5
6.2. Informative References . . . . . . . . . . . . . . . . . 5
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
The Dynamic Link Exchange Protocol (DLEP) is defined in [RFC8175].
It provides the exchange of link related control information between
DLEP peers. DLEP peers are comprised of a modem and a router. DLEP
defines a base set of mechanisms as well as support for possible
extensions. This document defines one such extension.
The base DLEP specification does not include any flow control
capability. There are various flow control techniques theoretically
possible with DLEP. For example, a credit-window scheme for
destination-specific flow control which provides aggregate flow
control for both modem and routers has been proposed in
[I-D.ietf-manet-credit-window].
This document defines a DLEP extension which provides a flow control
mechanism for traffic sent from a router to a modem. Flow control is
provided using one or more logical "Credit Windows", each of which
will typically be supported by an associated virtual or physical
queue. Traffic sent by a router will use traffic flow classification
information provided by the modem to identify which traffic is
associated with each credit window. (For general background on
traffic classification see [RFC2475] Section 2.3.) Credit windows
may be shared or dedicated on a per flow basis. The extension is
structured to allow for reuse of the defined credit window based flow
control with different traffic classification techniques.
This document uses the traffic classification and credit window
control mechanisms defined in [I-D.ietf-manet-credit-flow-control] to
provided credit window based flow control based on on DLEP
destination and DiffServ [RFC2475] DSCPs (differentiated services
codepoints). The defined mechanism allows for credit windows to be
shared across traffic sent to multiple DLEP destinations and DSCPs,
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or used exclusively for traffic 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
Aware Credit Window" or, more simply, the "DA Credit" extension. The
reader should be familiar with both the traffic classification and
credit window control mechanisms defined in
[I-D.ietf-manet-credit-flow-control].
This document defines a new DLEP Extension Type Value in Section 2
which is used to indicate support for the extension.
1.1. Key Words
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.
2. Extension Usage and Identification
The extension defined in this document is composed of the mechanisms
and processing defined in [I-D.ietf-manet-credit-flow-control]. To
indicate that the 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. The Extensions
Supported Data Item is sent and processed according to [RFC8175].
Any implementation that indicates use of the DiffServ Aware Credit
Window Extension MUST support all Messages, Data Items, the DiffServ
Traffic Classification Sub Data Item, and all related processing
defined in [I-D.ietf-manet-credit-flow-control].
The DiffServ Aware Credit Window Extension Type Value is TBA1, see
Section 5.
3. Management Considerations
This section provides several network management guidelines to
implementations supporting the DiffServ Aware Credit Window
Extension.
The use of the extension defined in this document SHOULD be
configurable on both modems and routers.
Modems SHOULD support the configuration of DSCP to credit window
(queue) mapping.
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Modems MAY support the configuration of the number of credit windows
(queues) to advertise to a router.
Routers may have limits on the number of queues that they can support
and, perhaps, even limits in supported credit window combinations,
e.g., if per destination queues can even be supported at all. When
modem-provided credit window information exceeds the capabilities of
a router, the router MAY use a subset of the provided credit windows.
Alternatively, a router MAY reset the session and indicate that the
extension is not supported. In either case, the mismatch of
capabilities SHOULD be reported to the user via normal network
management mechanisms, e.g., user interface or error logging.
4. Security Considerations
This document defines a DLEP extension that uses base DLEP mechanisms
and the credit window control and flow mechanisms defined in
[I-D.ietf-manet-credit-flow-control]. The use of those mechanisms,
and the introduction of a new extension, do not inherently introduce
any additional threats above those documented in [RFC8175]. The
approach taken to Security in that document applies equally to the
mechanism defined in this document.
5. IANA Considerations
This document requests one assignment by IANA. All assignments are
to registries defined by [RFC8175].
5.1. Extension Type Value
This document requests 1 new assignment to the DLEP Extensions
Registry named "Extension Type Values" in the range with the
"Specification Required" policy. The requested value is as follows:
+------+------------------------------+
| Code | Description |
+------+------------------------------+
| TBA1 | DiffServ Aware Credit Window |
+------+------------------------------+
Table 1: Requested Extension Type Value
6. References
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6.1. Normative References
[I-D.ietf-manet-credit-flow-control]
IETF, "DLEP Credit-Based Flow Control Messages and Data
Items", April 2018.
[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>.
[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>.
[RFC8175] Ratliff, S., Jury, S., Satterwhite, D., Taylor, R., and B.
Berry, "Dynamic Link Exchange Protocol (DLEP)", RFC 8175,
DOI 10.17487/RFC8175, June 2017,
<https://www.rfc-editor.org/info/rfc8175>.
6.2. Informative References
[I-D.ietf-manet-credit-window]
Ratliff, S., "Credit Windowing extension for DLEP", draft-
ietf-manet-credit-window-07 (work in progress), November
2016.
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
and W. Weiss, "An Architecture for Differentiated
Services", RFC 2475, DOI 10.17487/RFC2475, December 1998,
<https://www.rfc-editor.org/info/rfc2475>.
Appendix A. Acknowledgments
The sub data item format was inspired by Rick Taylor's "Data Item
Containers". He also proposed the separation of credit windows from
traffic classification at IETF98. Many useful comments were received
from contributors to the MANET working group.
Authors' Addresses
Bow-Nan Cheng
Lincoln Laboratory
Massachusetts Institute of Technology
244 Wood Street
Lexington, MA 02421-6426
Email: bcheng@ll.mit.edu
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David Wiggins
Lincoln Laboratory
Massachusetts Institute of Technology
244 Wood Street
Lexington, MA 02421-6426
Email: David.Wiggins@ll.mit.edu
Lou Berger
LabN Consulting, L.L.C.
Email: lberger@labn.net
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