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Versions: (draft-zheng-netconf-udp-pub-channel) 00 01 02

NETCONF                                                         G. Zheng
Internet-Draft                                                   T. Zhou
Intended status: Standards Track                                A. Clemm
Expires: September 19, 2018                                       Huawei
                                                          March 18, 2018


         UDP based Publication Channel for Streaming Telemetry
                 draft-ietf-netconf-udp-pub-channel-02

Abstract

   This document describes a UDP-based publication channel for streaming
   telemetry use to collect data from devices.  A new shim header is
   proposed to facilitate the distributed data collection mechanism
   which directly pushes data from line cards to the collector.  Because
   of the lightweight UDP encapsulation, higher frequency and better
   transit performance can be achieved.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

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 https://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 September 19, 2018.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.





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   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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Solution Overview . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Transport Mechanisms  . . . . . . . . . . . . . . . . . . . .   5
     4.1.  Dynamic Subscription  . . . . . . . . . . . . . . . . . .   5
     4.2.  Configured Subscription . . . . . . . . . . . . . . . . .   6
   5.  UDP Transport for Publication Channel . . . . . . . . . . . .   7
     5.1.  Design Overview . . . . . . . . . . . . . . . . . . . . .   7
     5.2.  Data Format of the Message Header . . . . . . . . . . . .   8
     5.3.  Options . . . . . . . . . . . . . . . . . . . . . . . . .   9
       5.3.1.  Reliability Option  . . . . . . . . . . . . . . . . .  10
       5.3.2.  Fragmentation Option  . . . . . . . . . . . . . . . .  11
     5.4.  Data Encoding . . . . . . . . . . . . . . . . . . . . . .  11
   6.  Congestion Control  . . . . . . . . . . . . . . . . . . . . .  12
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  12
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  13
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  13
     10.2.  Informative References . . . . . . . . . . . . . . . . .  13
     10.3.  URIs . . . . . . . . . . . . . . . . . . . . . . . . . .  14
   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  15

1.  Introduction

   Streaming telemetry refers to sending a continuous stream of
   operational data from a device to a remote receiver.  This provides
   an ability to monitor a network from remote and to provide network
   analytics.  Devices generate telemetry data and push that data to a
   collector for further analysis.  By streaming the data, much better
   performance, finer-grained sampling, monitoring accuracy, and
   bandwidth utilization can be achieved than with polling-based
   alternatives.





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   Sub-Notif [I-D.ietf-netconf-subscribed-notifications] and YANG-Push
   [I-D.ietf-netconf-yang-push] defines a mechanism that allows a
   collector to subscribe to updates of YANG-defined data that is
   maintained in a YANG [RFC7950] datastore.  The mechanism separates
   the management and control of subscriptions from the transport that
   is used to actually stream and deliver the data.  Two transports,
   NETCONF transport [I-D.ietf-netconf-netconf-event-notifications] and
   HTTP transport [I-D.ietf-netconf-restconf-notif], have been defined
   so far for the notification messages.

   While powerful in its features and general in its architecture, in
   its current form the mechanism needs to be extended to stream
   telemetry data at high velocity from devices that feature a
   distributed architecture.  The transports that have been defined so
   far, NETCONF and HTTP, are ultimately based on TCP and lack the
   efficiency needed to stream data continuously at high velocity.  A
   lighter-weight, more efficient transport, e.g. a transport based on
   UDP is needed.

   o  Firstly, data collector will suffer a lot of TCP connections from,
      for example, many line cards equipped on different devices.

   o  Secondly, as no connection state needs to be maintained, UDP
      encapsulation can be easily implemented by hardware which will
      further improve the performance.

   o  Thirdly, because of the lightweight UDP encapsulation, higher
      frequency and better transit performance can be achieved, which is
      important for streaming telemetry.

   This document specifies a higher-performance transport option for
   YANG-Push that leverages UDP.  Specifically, it facilitates the
   distributed data collection mechanism described in
   [I-D.zhou-netconf-multi-stream-originators].  In the case of data
   originating from multiple line cards, the centralized design requires
   data to be internally forwarded from those line cards to the push
   server, presumably on a main board, which then combines the
   individual data items into a single consolidated stream.  The
   centralized data collection mechanism can result in a performance
   bottleneck, especially when large amounts of data are involved.  What
   is needed instead is the support for a distributed mechanism that
   allows to directly push multiple individual substreams, e.g. one from
   each line card, without needing to first pass them through an
   additional processing stage for internal consolidation, but still
   allowing those substreams to be managed and controlled via a single
   subscription.  The proposed UDP based Publication Channel (UPC)
   natively supports the distributed data collection mechanism.




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   The transport described in this document can be used for transmitting
   notification messages over both IPv4 and IPv6 [RFC8200].

   While this document will focus on the data publication channel, the
   subscription can be used in conjunction with the mechanism proposed
   in [I-D.ietf-netconf-yang-push] with extensions
   [I-D.zhou-netconf-multi-stream-originators].

2.  Terminology

   Streaming Telemetry: refers to sending a continuous stream of
   operational data from a device to a remote receiver.  This provides
   an ability to monitor a network from remote and to provide network
   analytics.

3.  Solution Overview

   The typical distributed data collection solution is shown in Fig. 1.
   Both the Collector and the Subscribed Domain can be distributed.  The
   Collector includes the Subscriber and a set of Receivers.  And the
   Subscribed Domain includes a Master and a set of Agents.  The
   Subscriber cannot see the Agents directly, so it will send the Global
   Subscription information to the Master (e.g., main board) via the
   Subscription Channel.  When receiving a Global Subscription, the
   Master decomposes the subscription request into multiple Component
   Subscriptions, each involving data from a separate internal telemetry
   source, for example a line card.  The Component Subscriptions are
   distributed to the Agents.  Subsequently, each data originator
   generates its own stream of telemetry data, collecting and
   encapsulating the packets per the Component Subscription and
   streaming them to the designated Receivers.  This distributed data
   collection mechanism may form multiple Publication Channels between
   the Data Originators and the Receivers.  The Collector is able to
   assemble many pieces of data associated with one Global Subscription.

   The Publication Channel supports the reliable data streaming, for
   example for some alarm events.  The Collector has the option of
   deducing the packet loss and the disorder based on the information
   carried by the notification data.  And the Collector will decide the
   behavior to request retransmission.

   The rest of the draft describes the UDP based Publication Channel
   (UPC).








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                    +---------------------------------+
                    |            Collector            |
                    |                                 |
                    |  +------------+  +-----------+  |
                    |  | Subscriber |  | Receivers |  |
                    |  +----+-------+  +--^----^---+  |
                    |       |             |    |      |
                    +---------------------------------+
                            |             |    |
               Subscription |             |    | Publication
               Channel      |             |    | Channel
                            |   +---------+    |
                            |   |              |
                    +---------------------------------+
                    |       |   |              |      |
                    |   +---v---+--+    +------+-+    |
                    |   |  Master  |    | Agents |    |
                    |   +----------+    +--------+    |
                    |                                 |
                    |        Subscribed Domain        |
                    +---------------------------------+


                    Fig. 1 Distributed Data Collection

4.  Transport Mechanisms

   For a complete pub-sub mechanism, this section will describe how the
   UPC is used to interact with the Subscription Channel relying on
   NETCONF or RESTCONF.

4.1.  Dynamic Subscription

   Dynamic subscriptions for YANG-Push [I-D.ietf-netconf-yang-push] are
   configured and managed via signaling messages transported over
   NETCONF [RFC6241] or RESTCONF [RFC8040].  The YANG-Push defined RPCs
   are sent and responded via the Subscription Channel (a), between the
   Subscriber and the Master of the Subscribed Domain.  In this case,
   only one Receiver is associated with the Subscriber.  In the
   Subscribed Domain, there may be multiple Data Originators.
   Notification messages are pushed on separate channels (b), from
   different Data Originators to the Receiver .









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   +--------------+                         +--------------+
   |  Collector   |                         |  Subscribed  |
   |              |                         |  Domain      |
   |  (a)   (b)   |                         |  (a)    (b)  |
   +--+------+----+                         +--+-------+---+
      |      |                                 |       |
      |      |     RPC:establish-subscription  |       |
      +---------------------------------------->       |
      |      |     RPC Reply: OK               |       |
      <----------------------------------------+       |
      |      |     UPC:notifications           |       |
      |      <-----------------------------------------+
      |      |                                 |       |
      |      |     RPC:modify-subscription     |       |
      +---------------------------------------->       |
      |      |     RPC Reply: OK               |       |
      <----------------------------------------+       |
      |      |     UPC:notifications           |       |
      |      <-----------------------------------------+
      |      |                                 |       |
      |      |     RPC:delete subscription     |       |
      +---------------------------------------->       |
      |      |     RPC Reply: OK               |       |
      <----------------------------------------+       |
      |      |                                 |       |
      |      |                                 |       |
      +      +                                 +       +

                 Fig. 2 Call Flow for Dynamic Subscription

   In the case of dynamic subscription, the Receiver and the Subscriber
   SHOULD be collocated.  So UPC can use the source IP address of the
   Subscription Channel as it's destination IP address.  The Receiver
   MUST support listening messages at the IANA-assigned PORT-X, but MAY
   be configured to listen at a different port.

4.2.  Configured Subscription

   For a Configured Subscription, there is no guarantee that the
   Subscriber is currently in place with the associated Receiver(s).  As
   defined in [I-D.ietf-netconf-yang-push], the subscription
   configuration contains the location information of all the receivers,
   including the IP address and the port number.  So that the Data
   Originator can actively send generated messages to the corresponding
   Receivers via the UPC.






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   The first message MUST be a separate subscription-started
   notification to indicate the Receiver that the pushing is started.
   Then, the notifications can be sent immediately without any wait.

   All the subscription state notifications, as defined in
   [I-D.ietf-netconf-subscribed-notifications], MUST be encapsulated to
   be separated notification messages.

   +--------------+                         +--------------+
   |  Collector   |                         |  Subscribed  |
   |              |                         |  Domain      |
   |  (a)   (b)   |                         |  (a)    (b)  |
   +--+------+----+                         +--+-------+---+
      |      |                                 |       |
      |      |     Capability Exchange         |       |
      <---------------------------------------->       |
      |      |                                 |       |
      |      |     Edit config(create)         |       |
      +---------------------------------------->       |
      |      |     RPC Reply: OK               |       |
      <----------------------------------------+       |
      |      |     UPC:subscription started    |       |
      |      <-----------------------------------------+
      |      |     UPC:notifications           |       |
      |      <-----------------------------------------+
      |      |                                 |       |
      |      |     Edit config(delete)         |       |
      +---------------------------------------->       |
      |      |     RPC Reply: OK               |       |
      <----------------------------------------+       |
      |      |     UPC:subscription terminated |       |
      |      <-----------------------------------------+
      |      |                                 |       |
      |      |                                 |       |
      +      +                                 +       +

               Fig. 3 Call Flow for Configured Subscription

5.  UDP Transport for Publication Channel

5.1.  Design Overview

   As specified in YANG-Push, the telemetry data is encapsulated in the
   NETCONF/RESTCONF notification message, which is then encapsulated and
   carried in the transport protocols, e.g.  TLS, HTTP2.  The following
   figure shows the overview of the typical UDP publication message
   structure.




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   o  The Message Header contains information that can facilitate the
      message transmission before de-serializing the notification
      message.

   o  Notification Message is the encoded content that the publication
      channel transports.  The common encoding method includes GPB [1],
      CBOR [RFC7049], JSON, and XML.
      [I-D.ietf-netconf-notification-messages] describes the structure
      of the Notification Message for both single notification and
      multiple bundled notifications.

               +-------+  +--------------+  +--------------+
               |  UDP  |  |   Message    |  | Notification |
               |       |  |   Header     |  | Message      |
               +-------+  +--------------+  +--------------+

                  Fig. 4 UDP Publication Message Overview

5.2.  Data Format of the Message Header

   The Message Header contains information that can facilitate the
   message transmission before de-serializing the notification message.
   The data format is shown as follows.

      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
     +-------+---------------+-------+-------------------------------+
     | Vers. |    Flag       |  ET   |      Length                   |
     +-------+---------------+-------+-------------------------------+
     |                  Subscribed Domain ID                         |
     +---------------------------------------------------------------+
     |                       Message ID                              |
     +---------------------------------------------------------------+
     ~                       Options                                 ~
     +---------------------------------------------------------------+


                       Fig. 5 Message Header Format

   The Message Header contains the following field:

   o  Vers.: represents the PDU (Protocol Data Unit) encoding version.
      The initial version value is 0.

   o  Flag: is a bitmap indicating what features this packet has and the
      corresponding options attached.  Each bit associates to one
      feature and one option data.  When the bit is set to 1, the
      associated feature is enabled and the option data is attached.



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      The sequence of the presence of the options follows the bit order
      of the bitmap.  In this document, the flag is specified as
      follows:

      *  bit 0, the reliability flag;

      *  bit 1, the fragmentation flag;

      *  other bits are reserved.  All the reserved bits MUST be set to
         0.

   o  ET: is a 4 bits identifier to indicate the encoding type used for
      the Notification Message.  While 16 types of encoding can be
      expressed, this document specifies the following usage:

      *  0: GPB;

      *  1: CBOR;

      *  2: JSON;

      *  3: XML;

      *  others are reserved.

   o  Length: is the total length of the message, measured in octets,
      including message header.  If the notification message is
      fragmented, this Length indicates the actual length of the current
      message fragmentation.

   o  Subscribed Domain ID: is a 32-bit identifier of the Subscribed
      Domain.  With this parameter, the receiver can easily identify
      messages generated from the same Subscription Domain.  One
      possible value is the visible IPv4 address of the Master.

   o  The Message ID is generated continuously by the Data Originator.
      Different subscribers share the same Message ID sequence.
      Different fragmentations of one message share the same Message ID.

   o  Options: is a variable-length field.  The details of the Options
      will be described in the respective sections below.

5.3.  Options

   The order of packing the data fields in the Options field follows the
   bit order of the Flag field.





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5.3.1.  Reliability Option

   The UDP based publication transport described in this document
   provides two streaming modes, the reliable mode an the unreliable
   mode, for different SLA (Service Level Agreement) and telemetry
   requirements.

   In the unreliable streaming mode, the line card pushes the
   encapsulated data to the data collector without any sequence
   information.  So the subscriber does not know whether the data is
   correctly received or not.

   The reliable streaming mode provides sequence information in the UDP
   packet, based on which the subscriber can deduce the packet loss and
   disorder.  Then the subscriber can decide whether to request the
   retransmission of the lost packets.

   In most case, the unreliable streaming mode is preferred.  Because
   the reliable streaming mode will cost more network bandwidth and
   precious device resource.  Different from the unreliable streaming
   mode, the line card cannot remove the sent reliable notifications
   immediately, but to keep them in the memory for a while.  Reliable
   notifications may be pushed multiple times, which will increase the
   traffic.  When choosing the reliable streaming mode or the unreliable
   streaming mode, the operate need to consider the reliable requirement
   together with the resource usage.

   When the reliability flag bit is set to 1 in the Flag field, the
   following option data will be attached

      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
     +---------------------------------------------------------------+
     |            Previous Message ID                                |
     +---------------------------------------------------------------+

                     Fig. 4 Reliability Option Format

   The Data Originator has the capability of index the Previous Message
   ID for the message.  Together with the current Message ID, the
   Receiver can detect whether the current message is in a right order.

   For example, there are two subscriber A and B,

   o  Message IDs for the generator are : [1, 2, 3, 4, 5, 6, 7, 8, 9],
      in which Subscriber A subscribes [1,2,3,6,7] and Subscriber B
      subscribes [1,2,4,5,7,8,9].




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   o  Subscriber A will receive : [0,1][1,2][2,3][3,6][6,7].

   o  Subscriber B will receive : [0,1][1,2][2,4][4,5][5,7][7,8].

5.3.2.  Fragmentation Option

   UDP payload has a theoretical length limitation to 65535.  Other
   encapsulation headers will make the actual payload even shorter.
   Binary encodings like GPB and CBOR can generate a compact
   notification message.  So that the message can fit in one UDP packet.
   In this case, fragmentation will not easily happen.  However, text
   encodings like JSON and XML can easily generate a notification
   message exceeding the UDP length limitation.

   The fragmentation flag in the fixed header is set to 1 only when the
   Notification Message is actually fragmented.  And the Fragmentation
   Option is available in the message header when the fragmentation flag
   is set to 1.

   The Fragmentation Option is formatted as follow:

    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
   +-------------------------------------------------------------+-+
   |            Fragment Number                                   |L|
   +---------------------------------------------------------------+

                    Fig. 5 Fragmentation Option Format

   This option contains:

   o  Fragment Number: indicates the sequence number of the current
      fragment.  Together with the Message ID, the Receiver can compose
      the entire Notification Message.

   o  L: is a flag to indicate whether the current fragment is the last
      one.  When 0 is set, current fragment is not the last one, hence
      more fragments are expected.  When 1 is set, current fragment is
      the last one.

5.4.  Data Encoding

   Subscribed data can be encoded in GPB, CBOR, XML or JSON format.  It
   is conceivable that additional encodings may be supported as options
   in the future.  This can be accomplished by augmenting the
   subscription data model with additional identity statements used to
   refer to requested encodings.




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   Implementation may support different encoding method per
   subscription.  When bundled notifications is supported between the
   publisher and the receiver, only subscribed notifications with the
   same encoding can be bundled as one message.

6.  Congestion Control

   Congestion control mechanisms that respond to congestion by reducing
   traffic rates and establish a degree of fairness between flows that
   share the same path are vital to the stable operation of the Internet
   [RFC2914].  While efficient, UDP has no build-in congestion control
   mechanism.  Because streaming telemetry can generate unlimited
   amounts of data, transferring this data over UDP is generally
   problematic.  It is not recommended to use the UPC over congestion-
   sensitive network paths.  The only environments where the UPC MAY be
   used are managed networks.  The deployments require the network path
   has been explicitly provisioned for the UPC through traffic
   engineering mechanisms, such as rate limiting or capacity
   reservations.

7.  IANA Considerations

   This RFC requests that IANA assigns one UDP port number in the
   "Registered Port Numbers" range with the service names "udp-pub-ch".
   This port will be the default port for the UDP based publication
   channel for NETCONF and RESTCONF.  Below is the registration template
   following the rules in [RFC6335].

   Service Name: udp-pub-ch

   Transport Protocol(s): UDP

   Assignee: IESG <iesg@ietf.org>

   Contact: IETF Chair <chair@ietf.org>

   Description: NETCONF Call Home (SSH)

   Reference: RFC XXXX

   Port Number: PORT-X

8.  Security Considerations

   TBD






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9.  Acknowledgements

   The authors of this documents would like to thank Eric Voit, Tim
   Jenkins, and Huiyang Yang for the initial comments.

10.  References

10.1.  Normative References

   [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>.

   [RFC2914]  Floyd, S., "Congestion Control Principles", BCP 41,
              RFC 2914, DOI 10.17487/RFC2914, September 2000,
              <https://www.rfc-editor.org/info/rfc2914>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC7049]  Bormann, C. and P. Hoffman, "Concise Binary Object
              Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
              October 2013, <https://www.rfc-editor.org/info/rfc7049>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/info/rfc8040>.

   [RFC8200]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", STD 86, RFC 8200,
              DOI 10.17487/RFC8200, July 2017,
              <https://www.rfc-editor.org/info/rfc8200>.

10.2.  Informative References

   [I-D.ietf-netconf-netconf-event-notifications]
              Prieto, A., Voit, E., Clemm, A., Nilsen-Nygaard, E., and
              A. Tripathy, "NETCONF Support for Event Notifications",
              draft-ietf-netconf-netconf-event-notifications-08 (work in
              progress), February 2018.




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   [I-D.ietf-netconf-notification-messages]
              Voit, E., Birkholz, H., Bierman, A., Clemm, A., and T.
              Jenkins, "Notification Message Headers and Bundles",
              draft-ietf-netconf-notification-messages-03 (work in
              progress), February 2018.

   [I-D.ietf-netconf-restconf-notif]
              Voit, E., Tripathy, A., Nilsen-Nygaard, E., Clemm, A.,
              Prieto, A., and A. Bierman, "RESTCONF and HTTP Transport
              for Event Notifications", draft-ietf-netconf-restconf-
              notif-04 (work in progress), January 2018.

   [I-D.ietf-netconf-subscribed-notifications]
              Voit, E., Clemm, A., Prieto, A., Nilsen-Nygaard, E., and
              A. Tripathy, "Custom Subscription to Event Streams",
              draft-ietf-netconf-subscribed-notifications-10 (work in
              progress), February 2018.

   [I-D.ietf-netconf-yang-push]
              Clemm, A., Voit, E., Prieto, A., Tripathy, A., Nilsen-
              Nygaard, E., Bierman, A., and B. Lengyel, "YANG Datastore
              Subscription", draft-ietf-netconf-yang-push-15 (work in
              progress), February 2018.

   [I-D.zhou-netconf-multi-stream-originators]
              Zhou, T., Zheng, G., Voit, E., Clemm, A., and A. Bierman,
              "Subscription to Multiple Stream Originators", draft-zhou-
              netconf-multi-stream-originators-01 (work in progress),
              November 2017.

10.3.  URIs

   [1] https://developers.google.com/protocol-buffers/

Appendix A.  Change Log

   (To be removed by RFC editor prior to publication)

   A.1. draft-ietf-zheng-udp-pub-channel-00 to v00

   o  Modified the message header format.

   o  Added a section on the Authentication Option.

   o  Cleaned up the text and removed unnecessary TBDs.

   A.2. v01




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Internet-Draft               udp-pub-channel                  March 2018


   o  Removed the detailed description on distributed data collection
      mechanism from this document.  Mainly focused on the description
      of a UDP based publication channel for telemetry use.

   o  Modified the message header format.

   A.2. v02

   o  Add the section on the transport mechanism.

   o  Modified the fixed message header format.

   o  Add the fragmentation option for the message header.

Authors' Addresses

   Guangying Zheng
   Huawei
   101 Yu-Hua-Tai Software Road
   Nanjing, Jiangsu
   China

   Email: zhengguangying@huawei.com


   Tianran Zhou
   Huawei
   156 Beiqing Rd., Haidian District
   Beijing
   China

   Email: zhoutianran@huawei.com


   Alexander Clemm
   Huawei
   2330 Central Expressway
   Santa Clara, California
   USA

   Email: alexander.clemm@huawei.com










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