Network Working Group                                            E. Chen
Internet-Draft                                        Palo Alto Networks
Intended status: Standards Track                                 N. Shen
Expires: 30 May 6 June 2022                                              Zededa
                                                               R. Raszuk
                                                 NTT Network Innovations
                                                               R. Rahman
                                                        26 November
                                                         3 December 2021

              Unsolicited BFD for Sessionless Applications
                     draft-ietf-bfd-unsolicited-08
                     draft-ietf-bfd-unsolicited-09

Abstract

   For operational simplification of "sessionless" applications using
   BFD, in this document we present procedures for "unsolicited BFD"
   that allow a BFD session to be initiated by only one side, and be
   established without explicit per-session configuration or
   registration by the other side (subject to certain per-interface or
   per-router policies).

   We also introduce a new YANG module to configure and manage
   "unsolicited BFD".  The YANG module in this document conforms to the
   Network Management Datastore Architecture (NMDA) [RFC8342].

Requirements Language

   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.

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 30 May 6 June 2022.

Copyright Notice

   Copyright (c) 2021 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 Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Procedures for Unsolicited BFD  . . . . . . . . . . . . . . .   3
   3.  State Variables . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  YANG Data Model . . . . . . . . . . . . . . . . . . . . . . .   5
     4.1.  Unsolicited BFD Hierarchy . . . . . . . . . . . . . . . .   5
     4.2.  Unsolicited BFD Module  . . . . . . . . . . . . . . . . .   6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  10
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
     7.1.  BFD Protocol Security Considerations  . . . . . . . . . .  10  11
     7.2.  YANG Module Security Considerations . . . . . . . . . . .  11
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  12
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  13  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   The current implementation and deployment practice for BFD ([RFC5880]
   and [RFC5881]) usually requires BFD sessions be explicitly configured
   or registered on both sides.  This requirement is not an issue when
   an application like BGP [RFC4271] has the concept of a "session" that
   involves both sides for its establishment.  However, this requirement
   can be operationally challenging when the prerequisite "session" does
   not naturally exist between two endpoints in an application.
   Simultaneous configuration and coordination may be required on both
   sides for BFD to take effect.  For example:

   *  When BFD is used to keep track of the "liveness" of the nexthop of
      static routes.  Although only one side may need the BFD
      functionality, currently both sides need to be involved in
      specific configuration and coordination and in some cases static
      routes are created unnecessarily just for BFD.
   *  When BFD is used to keep track of the "liveness" of the third-pary
      nexthop of BGP routes received from the Route Server [RFC7947] at
      an Internet Exchange Point (IXP).  As the third-party nexthop is
      different from the peering address of the Route Server, for BFD to
      work, currently two routers peering with the Route Server need to
      have routes and nexthops from each other (although indirectly via
      the Router Server), and the nexthop of each router must be present
      at the same time.  These issues are also discussed in
      [I-D.ietf-idr-rs-bfd].

   Clearly it is beneficial and desirable to reduce or eliminate
   unnecessary configurations and coordination in these "sessionless"
   applications using BFD.

   In this document we present procedures for "unsolicited BFD" that
   allow a BFD session to be initiated by only one side, and be
   established without explicit per-session configuration or
   registration by the other side (subject to certain per-interface or
   per-router policies).

   With "unsolicited BFD" there is potential risk for excessive resource
   usage by BFD from "unexpected" remote systems.  To mitigate such
   risks, several mechanisms are recommended in the Security
   Considerations section.

   Compared to the "Seamless BFD" [RFC7880], this proposal involves only
   minor procedural enhancements to the widely deployed BFD itself.
   Thus we believe that this proposal is inherently simpler in the
   protocol itself and deployment.  As an example, it does not require
   the exchange of BFD discriminators over an out-of-band channel before
   the BFD session bring-up.

   When BGP Add-Path [RFC7911] is deployed at an IXP using the Route
   Server, multiple BGP paths (when exist) can be made available to the
   clients of the Router Server as described in [RFC7947].  The
   "unsolicited BFD" can be used in BGP route selection by these clients
   to eliminate paths with "inaccessible nexthops".

2.  Procedures for Unsolicited BFD

   With "unsolicited BFD", one side takes the "Active role" and the
   other side takes only the "Passive role" as described in [RFC5880].

   On the passive side, the "unsolicited BFD" SHOULD be explicitly
   configured on an interface or globally (apply to all interfaces).
   The BFD parameters can be either per-interface or per-router based.
   It MAY also choose to use the parameters that the active side uses in
   its BFD Control packets.  The "My Discriminator", however, MUST be
   chosen to allow multiple unsolicited BFD sessions.

   The active side starts sending the BFD Control packets as specified
   in [RFC5880].  The passive side does not send BFD Control packets.

   When the passive side receives a BFD Control packet from the active
   side with 0 as "Your Discriminator" and does not find an existing BFD
   session, the passive side MAY create a matching BFD session toward
   the active side, if permitted by local configuration.

   It would then start sending the BFD Control packets and perform
   necessary procedure for bringing up, maintaining and tearing down the
   BFD session.  If the BFD session fails to get established within
   certain specified time, or if an established BFD session goes down,
   the passive side would stop sending BFD Control packets and MAY
   delete the BFD session created until the BFD Control packets is
   initiated by the active side again.

   When an Unsolicited BFD session goes down, an implementation MAY
   retain the session state for a period of time, which may be
   configurable.  Retaining this state can be useful for operational
   purposes.

   The "Passive role" may change to the "Active role" when a local
   client registers for the same BFD session, and from the "Active role"
   to the "Passive role" when there is no longer any locally registered
   client for the BFD session.

3.  State Variables

   This document defines a new state variable called Unsolicited Role.

   bfd.UnsolicitedRole

   The operational mode of BFD interface when configured for unsolicited
   behaviour.  Options can be either PASSIVE, ACTIVE or NULL (NULL - not
   initialized) for unsolicited BFD sessions.  Default (not configured
   for unsolicited behaviour) MUST be set to NULL if present on the
   interface.

4.  YANG Data Model

   This section extends the YANG data model for BFD [RFC9127] to cover
   unsolicited BFD.  We import [RFC8349] since the "bfd" container in
   [RFC9127] is under "control-plane-protocol".

4.1.  Unsolicited BFD Hierarchy

   Configuration for unsolicited BFD parameters for IP single-hop
   sessions can be done at 2 levels:

   *  Globally, i.e. for all interfaces.  This requires support for the
      "unsolicited-params-global" feature.
   *  For specific interfaces.  This requires support for the
      "unsolicited-params-per-interface" feature.

   For operational data, a new "unsolicited" container has been added
   for BFD IP single-hop sessions.

   The tree diagram below uses the graphical representation of data
   models, as defined in [RFC8340].

   module: ietf-bfd-unsolicited

     augment /rt:routing/rt:control-plane-protocols
               /rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh:
       +--rw unsolicited {bfd-unsol:unsolicited-params-global}?
          +--rw enabled?                          boolean
          +--rw local-multiplier?                 multiplier
          +--rw (interval-config-type)?
             +--:(tx-rx-intervals)
             |  +--rw desired-min-tx-interval?    uint32
             |  +--rw required-min-rx-interval?   uint32
             +--:(single-interval) {single-minimum-interval}?
                +--rw min-interval?               uint32
     augment /rt:routing/rt:control-plane-protocols
               /rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh
               /bfd-ip-sh:interfaces:
       +--rw unsolicited {bfd-unsol:unsolicited-params-per-interface}?
          +--rw enabled enabled?                          boolean
          +--rw local-multiplier?                 multiplier
          +--rw (interval-config-type)?
             +--:(tx-rx-intervals)
             |  +--rw desired-min-tx-interval?    uint32
             |  +--rw required-min-rx-interval?   uint32
             +--:(single-interval) {single-minimum-interval}?
                +--rw min-interval?               uint32
     augment /rt:routing/rt:control-plane-protocols
               /rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh
               /bfd-ip-sh:sessions/bfd-ip-sh:session:
       +--ro unsolicited
          +--ro role?   bfd-unsol:unsolicited-role

4.2.  Unsolicited BFD Module

   <CODE BEGINS> file "ietf-bfd-unsolicited@2021-11-23.yang"
   module ietf-bfd-unsolicited {

     yang-version 1.1;

     namespace "urn:ietf:params:xml:ns:yang:ietf-bfd-unsolicited";

     prefix "bfd-unsol";

     // RFC Ed.: replace occurences of YYYY with actual RFC numbers
     // and remove this note

     import ietf-bfd-types {
       prefix "bfd-types";
       reference
         "RFC 9127: YANG Data Model for Bidirectional Forwarding Detection
         (BFD)";
     }

     import ietf-bfd {
       prefix "bfd";
       reference
         "RFC 9127: YANG Data Model for Bidirectional Forwarding Detection
          (BFD)";
     }

     import ietf-bfd-ip-sh {
       prefix "bfd-ip-sh";
       reference
         "RFC 9127: YANG Data Model for Bidirectional Forwarding Detection
         (BFD)";
     }

     import ietf-routing {
       prefix "rt";
       reference
         "RFC 8349: A YANG Data Model for Routing Management
          (NMDA version)";
     }

     organization "IETF BFD Working Group";

     contact
       "WG Web:   <https://datatracker.ietf.org/wg/bfd/>
        WG List:  <rtg-bfd@ietf.org>

        Editors:  Enke Chen (enchen@paloaltonetworks.com),
                  Naiming Shen (naiming@zededa.com),
                  Robert Raszuk (robert@raszuk.net),
                  Reshad Rahman (reshad@yahoo.com)";

     description
       "This module contains the YANG definition for BFD unsolicited
        as per RFC YYYY.

        Copyright (c) 2021 IETF Trust and the persons
        identified as authors of the code.  All rights reserved.

        Redistribution and use in source and binary forms, with or
        without modification, is permitted pursuant to, and subject
        to the license terms contained in, the Simplified BSD License
        set forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents
        (http://trustee.ietf.org/license-info).

        This version of this YANG module is part of RFC YYYY; see
        the RFC itself for full legal notices.";

     reference "RFC YYYY";

     revision 2021-11-23 {
       description
         "Initial revision.";
       reference
         "RFC YYYY: Unsolicited BFD for Sessionless Applications.";
     }

     /*
      * Feature definitions
      */
     feature unsolicited-params-global {
       description
         "This feature indicates that the server supports global
          parameters for unsolicited sessions.";
       reference
         "RFC YYYY: Unsolicited BFD for Sessionless Applications.";
     }

     feature unsolicited-params-per-interface {
       description
         "This feature indicates that the server supports per-interface
          parameters for unsolicited sessions.";
       reference
         "RFC YYYY: Unsolicited BFD for Sessionless Applications.";
     }

     /*
      * Type Definitions
      */
     typedef unsolicited-role {
       type enumeration {
         enum unsolicited-active {
           description "Active role";
         }
         enum unsolicited-passive {
           description "Passive role";
         }
       }
       description "Unsolicited role";

     }

     /*
      * Augments
      */
      augment "/rt:routing/rt:control-plane-protocols/"
            + "rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh" {
        if-feature bfd-unsol:unsolicited-params-global;
        description
          "Augmentation for BFD unsolicited parameters";
        container unsolicited {
          description
            "BFD unsolicited top level container";
          leaf enabled {
            type boolean;
            default false;
            description
              "BFD unsolicited enabled globally for IP single-hop.";
          }
          uses bfd-types:base-cfg-parms;
        }
      }

      augment "/rt:routing/rt:control-plane-protocols/"
            + "rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh/"
            + "bfd-ip-sh:interfaces" {
        if-feature bfd-unsol:unsolicited-params-per-interface;
        description
          "Augmentation for BFD unsolicited on IP single-hop interface";
        container unsolicited {
          description
            "BFD IP single-hop interface unsolicited top level
             container";
          leaf enabled {
            type boolean;
            default false;
            description
              "BFD unsolicited enabled on this interface.";
          }
          uses bfd-types:base-cfg-parms;
        }
      }

     augment "/rt:routing/rt:control-plane-protocols/"
           + "rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh/"
           + "bfd-ip-sh:sessions/bfd-ip-sh:session" {
       description
         "Augmentation for BFD unsolicited on IP single-hop session";

       container unsolicited {
         config false;
         description
           "BFD IP single-hop session unsolicited top level container";
         leaf role {
           type bfd-unsol:unsolicited-role;
           description "Role.";
         }
       }
     }
   }
   <CODE ENDS>

5.  IANA Considerations

   This document registers the following namespace URI in the "IETF XML
   Registry" [RFC3688]:

   URI: urn:ietf:params:xml:ns:yang:ietf-bfd-unsolicited

   Registrant Contact: The IESG.

   XML: N/A; the requested URI is an XML namespace.

   This document registers the following YANG module in the "YANG Module
   Names" registry [RFC6020]:

   Name: ietf-bfd-unsolicited

   Namespace: urn:ietf:params:xml:ns:yang:ietf-bfd-unsolicited

   Prefix: bfd-unsol

   Reference: RFC YYYY

6.  Acknowledgments

   Authors would like to thank Acee Lindem, Greg Mirsky, Jeffrey Haas,
   Raj Chetan and Tom Petch for their review and valuable input.

7.  Security Considerations
7.1.  BFD Protocol Security Considerations

   The same security considerations and protection measures as those
   described in [RFC5880] and [RFC5881] normatively apply to this
   document.  With "unsolicited BFD" there is potential risk for
   excessive resource usage by BFD from "unexpected" remote systems.  To
   mitigate such risks, the following measures are mandatory:

   *  Limit the feature to specific interfaces, and to a single-hop BFD
      with "TTL=255" [RFC5082].  For numbered interfaces, the source
      address of an incoming BFD packet should belong to the subnet of
      the interface on which the BFD packet is received.  For unnumbered
      interfaces the above check should be aligned with routing protocol
      addresses running on such pair of interfaces.
   *  Apply "policy" to allow BFD packets only from certain subnets or
      hosts.
   *  Deploy the feature only in certain "trustworthy" environment,
      e.g., at an IXP, or between a provider and its customers.
   *  Adjust BFD parameters as needed for the particular deployment and
      scale.
   *  Use BFD authentication.

7.2.  YANG Module Security Considerations

   The YANG module specified in this document defines a schema for data
   that is designed to be accessed via network management protocols such
   as NETCONF [RFC6241] or RESTCONF [RFC8040].  The lowest NETCONF layer
   is the secure transport layer, and the mandatory-to-implement secure
   transport is Secure Shell (SSH) [RFC6242].  The lowest RESTCONF layer
   is HTTPS, and the mandatory-to-implement secure transport is TLS
   [RFC8446].

   The NETCONF access control model [RFC8341] provides the means to
   restrict access for particular NETCONF or RESTCONF users to a
   preconfigured subset of all available NETCONF or RESTCONF protocol
   operations and content.

   There are a number of data nodes defined in this YANG module that are
   writable/creatable/deletable (i.e., config true, which is the
   default).  These data nodes may be considered sensitive or vulnerable
   in some network environments.  Write operations (e.g., edit-config)
   to these data nodes without proper protection can have a negative
   effect on network operations.  These are the subtrees and data nodes
   and their sensitivity/vulnerability:

   /routing/control-plane-protocols/control-plane-protocol/bfd/ip-sh
   /unsolicited:

   *  data node "enabled" enables creation of unsolicited BFD IP single-
      hop sessions globally, i.e. on all interfaces.  See Section 7.1.
   *  data nodes local-multiplier, desired-min-tx-interval, required-
      min-rx-interval and min-interval all impact the parameters of the
      unsolicited BFD IP single-hop sessions.

   /routing/control-plane-protocols/control-plane-protocol/bfd/ip-sh
   /interfaces/interface/unsolicited:

   *  data node "enabled" enables creation of unsolicited BFD IP single-
      hop sessions on a specific interface.  See Section 7.1.
   *  data nodes local-multiplier, desired-min-tx-interval, required-
      min-rx-interval and min-interval all impact the parameters of the
      unsolicited BFD IP single-hop sessions on the interface.

   Some of the readable data nodes in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control read access (e.g., via get, get-config, or
   notification) to these data nodes.  These are the subtrees and data
   nodes and their sensitivity/vulnerability:

   /routing/control-plane-protocols/control-plane-protocol/bfd/ip-sh
   /sessions/session/unsolicited: access to this information discloses
   the role of the local system in the creation of the unsolicited BFD
   session.

8.  References

8.1.  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>.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/info/rfc3688>.

   [RFC5082]  Gill, V., Heasley, J., Meyer, D., Savola, P., Ed., and C.
              Pignataro, "The Generalized TTL Security Mechanism
              (GTSM)", RFC 5082, DOI 10.17487/RFC5082, October 2007,
              <https://www.rfc-editor.org/info/rfc5082>.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
              <https://www.rfc-editor.org/info/rfc5880>.

   [RFC5881]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881,
              DOI 10.17487/RFC5881, June 2010,
              <https://www.rfc-editor.org/info/rfc5881>.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <https://www.rfc-editor.org/info/rfc6020>.

   [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>.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
              <https://www.rfc-editor.org/info/rfc6242>.

   [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>.

   [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>.

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/info/rfc8340>.

   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
              Access Control Model", STD 91, RFC 8341,
              DOI 10.17487/RFC8341, March 2018,
              <https://www.rfc-editor.org/info/rfc8341>.

   [RFC8349]  Lhotka, L., Lindem, A., and Y. Qu, "A YANG Data Model for
              Routing Management (NMDA Version)", RFC 8349,
              DOI 10.17487/RFC8349, March 2018,
              <https://www.rfc-editor.org/info/rfc8349>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/info/rfc8446>.

   [RFC9127]  Rahman, R., Ed., Zheng, L., Ed., Jethanandani, M., Ed.,
              Pallagatti, S., and G. Mirsky, "YANG Data Model for
              Bidirectional Forwarding Detection (BFD)", RFC 9127,
              DOI 10.17487/RFC9127, October 2021,
              <https://www.rfc-editor.org/info/rfc9127>.

8.2.  Informative References

   [I-D.ietf-idr-rs-bfd]
              Bush, R., Haas, J., Scudder, J. G., Nipper, A., and C.
              Dietzel, "Making Route Servers Aware of Data Link Failures
              at IXPs", Work in Progress, Internet-Draft, draft-ietf-
              idr-rs-bfd-09, 21 September 2020,
              <https://www.ietf.org/archive/id/draft-ietf-idr-rs-bfd-
              09.txt>.

   [RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
              Border Gateway Protocol 4 (BGP-4)", RFC 4271,
              DOI 10.17487/RFC4271, January 2006,
              <https://www.rfc-editor.org/info/rfc4271>.

   [RFC7880]  Pignataro, C., Ward, D., Akiya, N., Bhatia, M., and S.
              Pallagatti, "Seamless Bidirectional Forwarding Detection
              (S-BFD)", RFC 7880, DOI 10.17487/RFC7880, July 2016,
              <https://www.rfc-editor.org/info/rfc7880>.

   [RFC7911]  Walton, D., Retana, A., Chen, E., and J. Scudder,
              "Advertisement of Multiple Paths in BGP", RFC 7911,
              DOI 10.17487/RFC7911, July 2016,
              <https://www.rfc-editor.org/info/rfc7911>.

   [RFC7947]  Jasinska, E., Hilliard, N., Raszuk, R., and N. Bakker,
              "Internet Exchange BGP Route Server", RFC 7947,
              DOI 10.17487/RFC7947, September 2016,
              <https://www.rfc-editor.org/info/rfc7947>.

   [RFC8342]  Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
              and R. Wilton, "Network Management Datastore Architecture
              (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
              <https://www.rfc-editor.org/info/rfc8342>.

Authors' Addresses

   Enke Chen
   Palo Alto Networks

   Email: enchen@paloaltonetworks.com
   Naiming Shen
   Zededa

   Email: naiming@zededa.com

   Robert Raszuk
   NTT Network Innovations
   940 Stewart Dr
   Sunnyvale, CA 94085
   United States of America

   Email: robert@raszuk.net

   Reshad Rahman
   Canada

   Email: reshad@yahoo.com