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Versions: (draft-dunbar-idr-bgp-sdwan-overlay-ext) 00 01

Network Working Group                                         L. Dunbar
Internet Draft                                                   Huawei
Intended status: Standards Track                               S. Hares
Expires: September 4, 2019                                  Independent
                                                                 H. Wang
                                                                  W. Hao
                                                                  Huawei
                                                          March 4, 2019



            Subsequent Address Family Indicator for SDWAN Ports
                    draft-dunbar-idr-sdwan-port-safi-00

Abstract

   The document specifies a new BGP NLRI and SAFI for advertising
   properties of a SD-WAN edge node WAN ports that face untrusted
   networks, such as the public internet. Those WAN ports may get
   assigned IP addresses from the Internet Service Providers (ISPs),
   may get assigned dynamic IP addresses via DHCP, or may have private
   addresses (e.g. inside third party Cloud DCs). Packets sent over
   those SDWAN WAN ports might need to be encrypted (depending on the
   user policies) or need to go through NAT. SD-WAN edge need to
   propagate those WAN ports properties to its SDWAN controller, which
   propagates to the authorized peers and manage the IPsec SAs among
   those peers for encrypting traffic via the untrusted networks.

   BGP Route Reflectors (RR) are proposed as points of combination for
   this information in order to allow scaling of the SDWAN.

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), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six
   months and may be updated, replaced, or obsoleted by other documents



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   at any time.  It is inappropriate to use Internet-Drafts as
   reference material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt

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   This Internet-Draft will expire on September 4, 2019.

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
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   warranty as described in the Simplified BSD License.

Table of Contents


   1. Introduction...................................................3
   2. Conventions used in this document..............................5
   3. SD-WAN NLRI Format.............................................5
      3.1. SD-WAN Route Type.........................................8
      3.2. Port Distinguisher........................................8
      3.3. SD-WAN Color..............................................8
      3.4. Extended Port Property....................................8
      3.5. IPsec Security Association Property......................10
      3.6. Remote Endpoint..........................................11
   4. Manageability Considerations..................................12
   5. Security Considerations.......................................12
   6. IANA Considerations...........................................12
   7. References....................................................13



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      7.1. Normative References.....................................13
      7.2. Informative References...................................13
   8. Acknowledgments...............................................14

1. Introduction

   [Net2Cloud-Problem] introduces using SD-WAN to reach workloads in
   dynamic third party data centers and aggregate multiple underlay
   paths, including public untrusted networks, provided by different
   service providers. However, scaling the combination of routes and
   IPsec SAs key management can be an issue when the number of nodes
   interconnected by the SD-WAN overlay paths reaches 10,000 to 100,000
   nodes.

   [SDWAN-BGP-USAGE] describes multiple SDWAN scenarios and how/why
   using BGP as control plane for the SDWAN networks.

   This document describes a new BGP NLRI and SAFI to advertise
   properties of WAN ports facing the public internet. This new SAFI &
   NLRI is for the Scenario #2 of the [SDWAN-BGP-USAGE] where one
   "SDWAN" edge node having multiple ports some of which connected to
   private networks and others connected to public untrusted networks.
   The packets sent over the private networks can go natively without
   encryption (for better performance), only the packets sent over the
   public networks needs IPsec SA.

   The new SAFI and NLRI are for advertising the properties of WAN
   ports facing public untrusted networks, through which data packets
   have to be encrypted using IPsec.

   The [SDWAN-BGP-USAGE] document describes the three functional tiers
   for the control plane of SDWAN Scenario #2:

      . Tier 1 (Edge Router of SD-WAN): Each Edge SD-WAN router
         registers with the SD-WAN Controller using a secure connection
         (e.g. TLS).  During the registration process, the controller
         may suggest a specific BGP RR peer for the Edge SDWAN router
         to exchange BGP route with.

         After registering, each Edge Router sends routes + SDWAN WAN
         ports information (NAT and security information) via the SDWAN


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         SAFI + NLRI to the BGP RR.  Due to the sensitivity of the
         information, the BGP peering session MUST be configured to run
         over a Secure TCP (TLS).

      . Tier 2: Route Reflector that combines information from the
         security information from the SD-WAN controller, the WAN ports
         properties from SDWAN edge routers, and

      . Tier 3: Client routes distribution, just like EVPN or L3VPN,
         except including additional paths over the WAN ports facing
         the public Internet.

   Traffic go through the private networks links natively without
   encryption and are encrypted when sent out the WAN ports facing
   public Internet.

   The BGP peers use a new BGP NLRI and SAFI to pass the SDWAN Internet
   WAN ports properties, such as NAT and security association (SA).
   This information includes the Port-ID and port related NAT
   information, SD-WAN-SITE-ID, SD-WAN Node-ID, and IPsec security
   information.

     Centralized-----------------------------------------------
     controller                                               |
        |                                                     |
        |                     +---+                           |
        |        Peer Group 1 |RR |   Peer Group 2            |
        |       +======+====+=+   +======+====+=====+         |
        |      /      /     | +---+      |     \     \        |
        |     /      /      |            |      |     \       |
        |  +-+-+  +-+--+  +-+-+        +-+-+  +-+-+  +-+-+    |
        |  |CPE|  | CPE|--|CPE|        |CPE|  |CPE|  |CPE|    |
        ---| 1 |  |  2 |  | 3 |        |4  |  | 5 |  | 6 |----|
           +---+  +----+  +---+        +---+  +---+  +---+
               Tenant 1                   Tenant 2


         Figure 1: SD-WAN Capability Advertisement via RR

   Note: All CPEs (CPE1, CPE2, CPE, CPE4, CPE5, and CPE) connect to the
   centralized controller, but only 2 connections are show in this
   diagram.



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2. Conventions used in this document

   Cloud DC:   Off-Premise Data Centers that usually host applications
               and workload owned by different organizations or
               tenants.

   Controller: Used interchangeably with SD-WAN controller to manage
               SD-WAN overlay path creation/deletion and monitor the
               path conditions between sites.

   CPE-Based VPN: Virtual Private Secure network formed among CPEs.
               This is to differentiate from most commonly used PE-
               based VPNs a la RFC 4364.

   SD-WAN End-point: An WAN port (logical or physical) of a SD-WAN
               node.  (If "endpoint" is used, it refers to a SD-WAN
               End-point).

   OnPrem:     On Premises data centers and branch offices

   SD-WAN:     Software Defined Wide Area Network. In this document,
               "SDWAN" refers to the solutions of pooling WAN bandwidth
               from multiple underlay networks to get better WAN
               bandwidth management, visibility & control. When the
               underlay networks are private networks, traffic can
               traverse without additional encryption; when the
               underlay networks are public, such as Internet, some
               traffic needs to be encrypted when traversing through
               (depending on user provided policies).



3. SD-WAN NLRI Format

   The new SAFI code point 74 has been assigned by IANA as the
   Subsequent Address Family Identifier for advertising properties of
   WAN ports that face untrusted networks. Depending on user policies,
   some packets through those WAN ports will need encryption.




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   The SD-WAN SAFI (code point 74 assigned by IANA) uses a new NLRI
   defined as follows:

   +------------------+
   |   NLRI Length    | 1 octet
   +------------------+
   |   SDWAN-Type     | 2 Octets
   +------------------+
   |Port-Distinguisher| 4 octets
   +------------------+
   | SD-WAN-Site-ID   | 4 octets
   +------------------+
   | SD-WAN-Node-ID   | 4 or 16 octets
   +------------------+



   where:

     - NLRI Length: 1 octet of length expressed in bits as defined in
       [RFC4760].
     - SDWAN-Type: to define the encoding of the rest of the SD-WAN
       NLRI.
     - Port Distinguisher: SDWAN node Port identifier. There can be
       many ports on a SD-WAN node; each port can have different
       properties. For example, some ports may get ISP or DHCP assigned
       IP addresses (IPv4 or IPv6), some may have private IP addresses
       that packets to/from those ports have to traverse NAT.
       The detailed properties about the port are further encoded in
       the subsequent subTLVs, e.g. Port-subTLV.

     - SDWAN-Site-ID: used to identify a common property shared by a
       set of SD-WAN nodes, such as the property of a specific
       geographic location shared by a group of SDWAN nodes.
     - SDWAN Node ID: the SDWAN node identifier, which can be the
       node's system ID or the loopback address (IPv4 or IPv6) of the
       SD-WAN node.

   The content of the SDWAN Port properties is encoded in the Tunnel
   Encapsulation Attribute originally defined in [Tunnel-Encap] using a


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   new Tunnel-Type TLV (code point to be assigned by IANA from the "BGP
   Tunnel Encapsulation Attribute Tunnel Types" registry).

   SDWAN SAFI (=74) NLRI: < SDWAN-Type, Length, Port-distinguisher, SD-
   WAN-color, SD-WAN-Node-ID>
   Attributes:
      Tunnel Encaps Attribute
          Tunnel Type: SDWAN Port Property
              NAT SubTLV
              IPsec-SA Attribute SubTLV
              Port-subTLV

   Where
       - NAT SubTLV is for describing additional information about the
          SD-WAN tunnel end-points, such as NAT property.
       - IPsec-SA SubTLV is for the node to establish IPsec SA with
          other peers.
       - Port-subTLV is for additional properties of the WAN port.



   The Tunnel Encaps Attribute are defined 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Tunnel-Type(2 Octets)        | Length (2 Octets)              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                             Value                             |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
           Figure 1: SD-WAN Tunnel Encapsulation TLV Value Field

   Where:
      Tunnel Type is SD-WAN Port Property (to be assigned by IANA).









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3.1. SD-WAN Route Type

   A new Route Type that defines the encoding of the rest of the SD-WAN
   NLRI, and a set of sub-TLVs to specify its end-point attributes,
   policies associated with the Ports:


3.2. Port Distinguisher

   One (SD-WAN) node can have multiple ports, and each port can support
   multiple IPsec SA to different peers. The Port Distinguisher is to
   uniquely identify a port (or link).

   The property of the port are encoded in the subTLV attached to the
   SDWAN NLRI:

     a) The IP address (IPv4 or IPv6) & AS number of the Port
     b) NAT information for ports with Private IP address
     c) IPsec Security Association related information if the port is
        facing public network and traffic through which have to be
        encrypted.
   Detailed encoding for those properties are described in Section 3.4
   & Section 3.5 respectively.

3.3. SD-WAN Color

   SD-WAN Color is used to identify a common property shared by a set
   of SD-WAN nodes/ports, such as the property of a specific geographic
   location. The property is used to steer an overlay route to traverse
   specific geographic locations for various reasons, such as to comply
   regulatory rules, to utilize specific value added services, or
   others.



3.4. Extended Port Property

   EncapExt sub-TLV is for describing additional information about a
   SD-WAN port, such as the NAT property if the port has private
   address, the network identifier that the port is part of, etc.

   A SD-WAN edge node can inquire STUN (Session Traversal of UDP
   Through Network Address Translation RFC 3489) Server to get the NAT
   property, the public IP address and the Public Port number to pass
   to peers.


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        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |EncapExt Type  |  EncapExt subTLV Length       |I|O|R|R|R|R|R|R|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | NAT Type      |  Encap-Type   |Trans networkID|     RD ID     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Local  IP Address                            |
                  32-bits for IPv4, 128-bits for Ipv6
                          ~~~~~~~~~~~~
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                  Local  Port                                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                Public IP                                      |
                  32-bits for IPv4, 128-bits for Ipv6
                          ~~~~~~~~~~~~
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                Public Port                                    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Where:

     o EncapExt Type: indicate it is the EncapExt SubTLV.
     o EncapExt subTLV Length: the length of the subTLVE.
     o Flags:
          - I bit (CPE port address or Inner address scheme)
             If set to 0, indicate the inner (private) address is IPv4.
             If set to 1, it indicates the inner address is IPv6.

          - O bit (Outer address scheme):
             If set to 0, indicate the public (outer) address is IPv4.
             If set to 1, it indicates the public (outer) address is
             IPv6.

          - R bits: reserved for future use. Must be set to 0 now.


     o NAT Type.without NAT; 1:1 static NAT; Full Cone; Restricted
        Cone; Port Restricted Cone; Symmetric; or Unknown (i.e. no
        response from the STUN server).



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     o Encap Type.the supported encapsulation types for the port
        facing public network, such as IPsec+GRE, IPsec+VxLAN, IPsec
        without GRE, GRE (when packets don't need encryption)
     o Transport Network ID.Central Controller assign a global unique
        ID to each transport network.
     o RD ID.Routing Domain ID.Need to be global unique.
     o Local IP.The local (or private) IP address of the port.
     o Local Port.used by Remote SD-WAN node for establishing IPsec to
        this specific port.
     o Public IP.The IP address after the NAT. If NAT is not used,
        this field is set to NULL.
     o Public Port.The Port after the NAT. If NAT is not used, this
        field is set to NULL.

3.5. IPsec Security Association Property

   The IPsecSA sub-TLV is for the SD-WAN node to establish IPsec
   security association with their peers via the port that face
   untrusted network:

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |IPsec-SA Type  |IPsecSA Length                 | Flag          |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  Transform    | Transport    | AH             |   ESP         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         SPI                                                   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | key1 length   |         key1                                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | key2 length   |         key2                                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | key3 length   |         key3                                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |        Duration                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Where:






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     o IPsec-SA SubTLV Type: to be assigned by IANA. The type value
        has to be between 128~255 because IPsec-SA subTLV needs 2 bytes
        for length to carry the needed information.
     o IPsec-SA subTLV Length (2 Byte): 25 (or more)
     o Flags: 1 octet of flags. None are defined at this stage. Flags
        SHOULD be set to zero on transmission and MUST be ignored on
        receipt.
     o Transform (1 Byte):  the value can be AH, ESP, or AH+ESP.
     o Transport (1 byte): the value can be Tunnel Mode or Transport
        mode
     o AH (1 byte): AH authentication algorithms supported, which can
        be md5 | sha1 | sha2-256 | sha2-384 | sha2-512 | sm3. Each SD-
        WAN node can have multiple authentication algorithms; send to
        its peers to negotiate the strongest one.
     o ESP (1 byte): ESP authentication algorithms supported, which
        can be md5 | sha1 | sha2-256 | sha2-384 | sha2-512 | sm3. Each
        SD-WAN node can have multiple authentication algorithms; send
        to its peers to negotiate the strongest one. Default algorithm
        is AES-256.
     o SPI: 4 bytes
     o Key1.AH authentication key
     o Key2.ESP authentication key
     o Key3.ESP encryption "public" key
     o Duration: SA life span.

3.6. Remote Endpoint

   The Remote Endpoint sub-TLV is not used for SDWAN NLRI because
     o The network to which a SDWAN port is connected might have
        identifier that is more than the AS number. SDWAN controller
        might use its own specific identifier for the network.
     o The Transport-Network-ID in the EncapExt sub-TLV represents the
        SDWAN unique network identifier.

     If the Remote Endpoint Sub-TLV is present, it is ignored by other
     SDWAN nodes.


4. Operation of SDWAN routers:




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   The processing steps on CPE1 to announce the SD-WAN combination of
   routes, NAT and IPsec information via BGP are:


   1. Advertise the SD-WAN capability information and port properties,
   such as Port identifiers and supported properties etc. to RR via the
   SD-WAN SAFI NLRI.



   2.  RR propagate the information to CPE2 & CPE 3.

   3. CPE2 and CPE3 can choose to establish IPsec SA with the CPE1
   after receiving the CPE1 WAN properties from RR.



   Note: Tenant separation is achieved by different SD-WAN nodes being
   added to different Peer Group.



4. Manageability Considerations

      TBD - this needs to be filled out before publishing

5. Security Considerations

     The document is to address how SD-WAN nodes advertise its SD-WAN
     capability to their peers via untrusted & unsecure networks.

     The secure propagation is achieved by secure channels, such as
     TLS, SSL, or IPsec, between the SD-WAN nodes and the local
     controller RR.

    [More details need to be filled in here]


6. IANA Considerations

   This document requires the following IANA actions.

       o SD-WAN Overlay SAFI = 74 assigned by IANA


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       o SD-WAN Type

7. References


7.1. Normative References

   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997.
7.2. Informative References

   [RFC8192] S. Hares, et al, "Interface to Network Security Functions
             (I2NSF) Problem Statement and Use Cases", July 2017

   [RFC5521] P. Mohapatra, E. Rosen, "The BGP Encapsulation Subsequent
             Address Family Identifier (SAFI) and the BGP Tunnel
             Encapsulation Attribute", April 2009.

   [Tunnel-Encap]E. Rosen, et al, "The BGP Tunnel Encapsulation
             Attribute", draft-ietf-idr-tunnel-encaps-09, Feb 2018.

   [VPN-over-Internet] E. Rosen, "Provide Secure Layer L3VPNs over
             Public Infrastructure", draft-rosen-bess-secure-l3vpn-00,
             work-in-progress, July 2018

   [DMVPN] Dynamic Multi-point VPN:
             https://www.cisco.com/c/en/us/products/security/dynamic-
             multipoint-vpn-dmvpn/index.html

   [DSVPN] Dynamic Smart VPN:
             http://forum.huawei.com/enterprise/en/thread-390771-1-
             1.html



   [ITU-T-X1036] ITU-T Recommendation X.1036, "Framework for creation,
             storage, distribution and enforcement of policies for
             network security", Nov 2007.






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   [Net2Cloud-Problem] L. Dunbar and A. Malis, "Seamless Interconnect
             Underlay to Cloud Overlay Problem Statement", draft-dm-
             net2cloud-problem-statement-02, June 2018

   [Net2Cloud-gap] L. Dunbar, A. Malis, and C. Jacquenet, "Gap Analysis
             of Interconnecting Underlay with Cloud Overlay", draft-dm-
             net2cloud-gap-analysis-02, work-in-progress, Aug 2018.

   [Tunnel-Encap] E. Rosen, et al "The BGP Tunnel Encapsulation
             Attribute", draft-ietf-idr-tunnel-encaps-10, Aug 2018.



8. Acknowledgments

   Acknowledgements to Jim Guichard, John Scudder, Darren Dukes, Andy
   Malis and Donald Eastlake for their review and contributions.

   This document was prepared using 2-Word-v2.0.template.dot.



























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Authors' Addresses


   Linda Dunbar
   Huawei
   Email: Linda.Dunbar@huawei.com

   Sue Hares
   Independent
   Email: shares@ndzh.com

   Haibo Wang
   Huawei
   Email: rainsword.wang@huawei.com

   WeiGuo Hao
   Huawei Technologies Co.,Ltd.
   Email: haoweiguo@huawei.com

































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