Dynamic Link Exchange Protocol (DLEP) Control-Plane-Based Pause Extension
RFC 8651

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Internet Engineering Task Force (IETF)                          B. Cheng
Request for Comments: 8651                                    D. Wiggins
Category: Standards Track                         MIT Lincoln Laboratory
ISSN: 2070-1721                                           L. Berger, Ed.
                                                 LabN Consulting, L.L.C.
                                                            October 2019

                 Dynamic Link Exchange Protocol (DLEP)
                  Control-Plane-Based Pause Extension

Abstract

   This document defines an extension to the Dynamic Link Exchange
   Protocol (DLEP) that enables a modem to use DLEP messages to pause
   and resume data traffic coming from its peer router.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   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/rfc8651.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   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 and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction
     1.1.  Key Words
   2.  Extension Usage and Identification
   3.  Extension Data Items
     3.1.  Queue Parameters
       3.1.1.  Queue Parameter Sub-Data Item
     3.2.  Pause
     3.3.  Restart
   4.  Security Considerations
   5.  IANA Considerations
     5.1.  Extension Type Value
     5.2.  Data Item Values
     5.3.  Queue Parameter Sub-Data Item Values
   6.  References
     6.1.  Normative References
     6.2.  Informative References
   Acknowledgments
   Authors' Addresses

1.  Introduction

   The Dynamic Link Exchange Protocol (DLEP) is defined in [RFC8175].
   It provides the exchange of link-related control information between
   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 data-plane
   flow-control capability.  The extension defined in this document
   supports flow control of data traffic based on explicit messages sent
   via DLEP by a modem to indicate when a router should hold off sending
   traffic and when it should resume.  This functionality parallels the
   flow-control mechanism found in PPP over Ethernet (PPPoE) per
   [RFC5578].  The extension also optionally supports DSCP-aware flow
   control ("DSCP" stands for "Differentiated Services Code Point") for
   use by Diffserv-aware modems.  (For general background on
   Differentiated Services, see [RFC2475].)  This functionality is very
   similar to that provided by Ethernet priority-based flow control; see
   [IEEE.802.1Q_2014].  The extension defined in this document is
   referred to as "Control-Plane-Based Pause".  Other flow-control
   methods are possible with DLEP; for example, see [DLEP-DIFFSERV] and
   [DLEP-CREDIT].

   Note that this mechanism only applies to traffic that is to be
   transmitted on the modem's attached data channel and not to DLEP
   control messages themselves.  Furthermore, it applies only to the
   single subnetwork that is used to connect a modem and a router, and
   for traffic sent from a router to a modem.

   This document defines a new DLEP Extension Type Value that is used to
   indicate the use of the extension; see Section 2.  Three new DLEP
   Data Items are defined in Section 3.

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 use of the Control-Plane-Based Pause Extension SHOULD be
   configurable.  To indicate that the implementation supports the use
   of the Control-Plane-Based Pause Extension, an implementation MUST
   include the Control-Plane-Based Pause Extension Type Value in the