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Versions: 00 draft-ietf-manet-dlep-pause-extension

Network Working Group                                           B. Cheng
Internet-Draft                                                D. Wiggins
Intended status: Standards Track                      Lincoln Laboratory
Expires: April 30, 2017                                   L. Berger, Ed.
                                                 LabN Consulting, L.L.C.
                                                        October 27, 2016


                DLEP Control Plane Based Pause Extension
               draft-cheng-manet-dlep-pause-extension-00

Abstract

   This document defines an extension to the DLEP protocol that enables
   a simple control plane based flow control mechanism.

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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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 April 30, 2017.

Copyright Notice

   Copyright (c) 2016 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
   (http://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.




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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Key Words . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Extension Usage and Identification  . . . . . . . . . . . . .   3
   3.  Extension Data Items  . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Queue Parameters  . . . . . . . . . . . . . . . . . . . .   3
     3.2.  Pause . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.3.  Restart . . . . . . . . . . . . . . . . . . . . . . . . .   7
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
     5.1.  Extension Type Value  . . . . . . . . . . . . . . . . . .   8
     5.2.  Data Item Values  . . . . . . . . . . . . . . . . . . . .   8
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   The Dynamic Link Event Protocol (DLEP) is defined in
   [I-D.ietf-manet-dlep].  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 possible, e.g., see
   [I-D.ietf-manet-credit-window].  The extension defined in this
   document supports flow control 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.  The extension also optionally
   supports DSCP (differentiated services codepoint) aware, see
   [RFC2475], flow control.  The extension defined in this document is
   referred to as "Control Plane Pause".

   This document defines a new DLEP Extension Type Value in Section 2
   which is used to indicate the use of the extension, and three new
   DLEP Data Items 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, RFC 2119 [RFC2119].




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2.  Extension Usage and Identification

   The use of the Control Plane Pause Extension SHOULD be configurable.
   To indicate that the Control Plane Pause Extension is to be used, an
   implementation MUST include the Control Plane Pause Extension Type
   Value in the Extensions Supported Data Item.  The Extensions
   Supported Data Item is sent and processed according to
   [I-D.ietf-manet-dlep].

   The Control Plane Pause Extension Type Value is TBA1, see Section 5.

3.  Extension Data Items

   Three data items are defined by this extension.  The Queue Parameters
   Data Item is used by a modem to provide information on the DSCPs it
   uses in forwarding.  The Pause Data Item is used by a modem to
   indicate when a router should cease sending packets and the Restart
   Data Item is used by a modem to indicate when a router can resume
   sending packets.

3.1.  Queue Parameters

   The Queue Parameters Data Item is used by a modem to indicate DSCP
   values that may be independently paused.  This data item MUST be
   included in a Session Initialization Response Message that also
   contains the Control Plane Pause Extension Type Value in the
   Extensions Supported Data Item.  Updates to these parameters MAY be
   sent by a modem by including the data item in Session Update
   Messages.

   The Queue Parameters Data Item identifies DSCPs based on groups of
   logical queues.  The number of logical queues is variable as is the
   number of DSCPs associated with each queue.  A queue size (in bytes)
   is provided for informational purposes.  An implementation that does
   not support DSCPs would indicate 1 queue with 0 DSCPs, and the number
   of bytes that may be in its associated link transmit queue.

   The format of the Queue Parameters Data Item is:













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        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Data Item Type                | Length                        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Num Queues  | Scale |              Reserved                 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |Num DSCPs Q0(0)|             Queue Size Q0                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Num DSCPs Q1  |             Queue Size Q1                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Num DSCPs Q2  |             Queue Size Q2                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       :                                ...                            :
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Num DSCPs Qn  |             Queue Size Qn                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  DS Field Q1  |  DS Field Q1  |  DS Field Q1  |  DS Field Q2  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       :                                ...            |  DS Field Qn  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Data Item Type:  TBA2

   Length:  Variable

      Per [I-D.ietf-manet-dlep] Length is the number of octets in the
      data item, excluding the Type and Length fields.

   Num Queues:

      An 8-bit unsigned integer indicating the number of queues
      represented in the data item.  This field MUST contain a value of
      at least one (1).  Note that this number is one larger than the
      largest queue index value included in the data item.

   Scale:

      An 4-bit unsigned integer indicating the scale used in the Queue
      Size fields.  The valid values are:

         Value  Scale
         ------------
             0   B - Bytes     (Octets)
             1  KB - Kilobytes (B/1024)
             2  MB - Megabytes (KB/1024)
             3  GB - Gigabytes (MB/1024)




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   Reserved:

      MUST be set to zero by the sender (a modem) and ignored by the
      receiver (a router).

   Num DSCPs Qn:

      An 8-bit unsigned integer indicating the number of DSCPs
      associated with the indexed queue.  Other than the special case
      covered in the next paragraph, this field MUST contain a value of
      at least one (1).  Queue indexes start at zero (0) and the maximum
      queue index "Qn" is one less than the value carried in the Num
      Queues field.  Queue indexes are implicit in the position in the
      data item.

      Queue index zero "Q0" is a special case.  It is used for any
      traffic that does not carry a DSCP value represented in the data
      item.  Therefore the value of the Queue index zero field, "Num
      DSCPs Q0", field MUST be zero (0).

   Queue Size Qn:

      A 24-bit unsigned integer representing the size, in the octet
      scale indicated by the Scale field, of the queue supporting
      traffic with the DSCPs associated with the queue index.

   DS Field Qn:

      The data item contains a sequence of 8 bit DS Fields.  The
      position in the sequence identifies the associated queue index.
      The number of DS Fields present should equal the sum of all Num
      DSCPs field values.

      The DS Field structure is the same as [RFC2474].

           0   1   2   3   4   5   6   7
         +---+---+---+---+---+---+---+---+
         |         DSCP          |  CU   |
         +---+---+---+---+---+---+---+---+

           DSCP: differentiated services codepoint
           CU:   currently unused, MUST be zero

3.2.  Pause

   The Pause Data Item is used by a modem to indicate to its peer that
   traffic is to be suppressed.  An example of when a modem might send




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   this data item is when an internal queue length exceeds a particular
   threshold.

   A modem may indicate that traffic is to be suppressed on a device
   wide or destination specific basis.  An example of when a modem might
   use device wide indications is when output queues are shared across
   all destinations, and destination specific might be used when per
   destination queuing is used.  To indicate that suppression applies to
   all destinations, a modem MAY send the Pause Data Item in a Session
   Update Message.  To indicate that suppression applies to a particular
   destination a modem MAY send the Pause Data Item in a Destination
   Update Message.

   Each Pause Data Item identifies the traffic to be suppressed by the
   Queue Index defined by Section 3.1, which in turn indicates a set of
   traffic identified by DSCPs.  The special value of 255 is used to
   indicate that all traffic is to be suppressed.

   While there is no restriction on the number of Messages containing
   Pause Data Item that may be sent by a modem, a modem SHOULD include
   multiple queue indexes in the same message when possible.

   A router which receives the Pause Data Item MUST cease sending the
   identified traffic to the modem.  This may of course translate into
   the router's queues exceeding their own thresholds.

   The format of the Pause Data Item is:

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Data Item Type                | Length                        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  Queue Index  |               ...                             :
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       :                                ...            |  Queue Index  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   [LB note: a list of Queue Indexes is now supported as is special
   value 255.]

   Data Item Type:  TBA3

   Length:  Variable

      Per [I-D.ietf-manet-dlep] Length is the number of octets in the
      data item, excluding the Type and Length fields.  It will equal
      the number of Queue Index fields carried in the data item.



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   Queue Index:

      One or more 8-bit fields used to indicate a queue index defined by
      a Queue Parameters Data Item.  The special value of 255 indicates
      all traffic is to be suppressed to the modem, when the data item
      is carried in a Session Update Message, or a destination, when the
      data item is carried in Destination Update Message.

3.3.  Restart

   The Restart Data Item is used by a modem to indicate to its peer that
   transmission of previously suppressed traffic may be resumed.  An
   example of when a modem might send this data item is when an internal
   queue length drops below a particular threshold.

   The sending of this data item parallels the Pause Data Item, see the
   previous section, and follows the same rules.  This includes that to
   indicate that transmission can resume to all destinations, a modem
   MAY send the Restart Data Item in a Session Update Message.  It also
   includes that to indicate that transmission can resume to a
   particular destination a modem MAY send the Pause Restart Item in a
   Destination Update Message.  Finally, the same rules apply to queue
   indexes.

   A router which receives the Restart Data Item SHOULD resume
   transmission of the identified traffic to the modem.

   The format of the Restart Data Item matches the Pause Data Item and
   is:

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Data Item Type                | Length                        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  Queue Index  |               ...                             :
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       :                                ...            |  Queue Index  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Data Item Type:  TBA4

   Length:  See Section 3.2.

   Queue Index:  See Section 3.2.






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4.  Security Considerations

   The extension introduces a new mechanism for flow control between a
   router and modem using the DLEP protocol.  The extension does not
   inherently introduce any additional threats above those documented in
   [I-D.ietf-manet-dlep].  The approach taken to Security in that
   document applies equally when running the extension defined in this
   document.

5.  IANA Considerations

   This document requests the assignment of 4 values by IANA.  All
   assignments are to registries defined by [I-D.ietf-manet-dlep].

5.1.  Extension Type Value

   This document requests 1 new assignment to the DLEP Extensions
   Registry named "Extension Tyoe Values" in the range with the
   "Specification Required" policy.  The requested value is as follows:

                      +------+---------------------+
                      | Code | Description         |
                      +------+---------------------+
                      | TBA1 | Control Plane Pause |
                      +------+---------------------+

                  Table 1: Requested Extension Type Value

5.2.  Data Item Values

   This document requests 3 new assignments to the DLEP Data Item
   Registry named "Data Item Values" in the range with the
   "Specification Required" policy.  The requested values are as
   follows:

                     +-----------+------------------+
                     | Type Code | Description      |
                     +-----------+------------------+
                     | TBA2      | Queue Parameters |
                     |           |                  |
                     | TBA3      | Pause            |
                     |           |                  |
                     | TBA4      | Restart          |
                     +-----------+------------------+

                    Table 2: Requested Data Item Values





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6.  References

6.1.  Normative References

   [I-D.ietf-manet-dlep]
              Ratliff, S., Jury, S., Satterwhite, D., Taylor, R., and (.
              (Unknown), "Dynamic Link Exchange Protocol (DLEP)", draft-
              ietf-manet-dlep-24 (work in progress), July 2016.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

6.2.  Informative References

   [I-D.ietf-manet-credit-window]
              Ratliff, S., "Credit Windowing extension for DLEP", draft-
              ietf-manet-credit-window-04 (work in progress), April
              2016.

   [RFC2474]  Nichols, K., Blake, S., Baker, F., and D. Black,
              "Definition of the Differentiated Services Field (DS
              Field) in the IPv4 and IPv6 Headers", RFC 2474,
              DOI 10.17487/RFC2474, December 1998,
              <http://www.rfc-editor.org/info/rfc2474>.

   [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,
              <http://www.rfc-editor.org/info/rfc2475>.

Authors' Addresses

   Bow-Nan Cheng
   Lincoln Laboratory
   Massachusetts Institute of Technology
   244 Wood Street
   Lexington, MA  02420-9108

   Email: bcheng@ll.mit.edu










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   David Wiggins
   Lincoln Laboratory
   Massachusetts Institute of Technology
   244 Wood Street
   Lexington, MA  02420-9108

   Email: David.Wiggins@ll.mit.edu


   Lou Berger (editor)
   LabN Consulting, L.L.C.

   Email: lberger@labn.net






































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