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Versions: (draft-dunbar-idr-bgp-sdwan-overlay-ext) 00 01 02 03 04 05 06

Network Working Group                                         L. Dunbar
Internet Draft                                                Futurewei
Intended status: Informational                                 S. Hares
Expires: May 21, 2020                            Hickory Hill
Consulting

                                                      November 21, 2019




           SDWAN WAN Ports Property Advertisement in BGP UPDATE
                    draft-dunbar-idr-sdwan-port-safi-06

Abstract

   The document describes how the SDWAN SAFI, which is assigned by IANA
   in the First Come First Server range, is used for SDWAN edge nodes
   to propagate its WAN port properties to its controller.

   In the context of this document, BGP Route Reflectors (RR) is the
   component of the SDWAN Controller that receives the BGP UPDATE from
   SDWAN edges and in turns propagate the information to a group of
   authorized SDWAN edges reachable via overlay networks.

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
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   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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   The list of Internet-Draft Shadow Directories can be accessed at
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   This Internet-Draft will expire on Dec 5, 2020.

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..............................3
      2.1. Information to be propagated for SDWAN UPDATE.............4
      2.2. SAFI under the MP-NLRI....................................6
      2.3. How about a new Path Attribute under BGP UPDATE?..........6
   3. SDWAN WAN Port Identifer encoding in the MP-NLRI Path Attribute6
   4. WAN Port Properties encoding in the Tunnel Path Attribute......8
      4.1. Port Ext SubTLV for NAT...................................9
      4.2. IPsec Security Association Property......................10
      4.3. Remote Endpoint..........................................11
   5. Manageability Considerations..................................12
   6. Security Considerations.......................................12
   7. IANA Considerations...........................................12
   8. References....................................................12
      8.1. Normative References.....................................12
      8.2. Informative References...................................13
   9. Acknowledgments...............................................14





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1. Introduction

   [Net2Cloud-Problem] introduces using SDWAN to reach dynamic
   workloads in multiple third-party data centers and aggregate
   multiple underlay paths, including public untrusted networks,
   provided by different service providers.

   [SDWAN-BGP-USAGE] describes multiple SDWAN scenarios and illustrates
   how BGP is used as control plane for the SDWAN networks.


   The document describes BGP UPDATE for SDWAN edge nodes to propagate
   its WAN port properties to RR.

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 SDWAN controller to manage
               SDWAN 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.

   MP-NLRI:    The MP_REACH_NLRI Path Attribute defined in RFC4760.

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

   OnPrem:     On Premises data centers and branch offices

   SDWAN:      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 be


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               forwarded without additional encryption; when the
               underlay networks are public, such as Internet, some
               traffic needs to be encrypted when forwarding through
               those WAN ports (depending on user provided policies).


 2.1. Information to be propagated for SDWAN UPDATE

   Figure below shows the Hybrid SDWAN scenario:



                                       +---+
                        +--------------|RR |----------+
                       /  Untrusted    +-+-+           \
                      /                                 \
                     /                                   \
     +----+  +---------+  packets encrypted over     +------+  +----+
     | CN3|--|         A1-----+ Untrusted    +------ B1     |--| CN1|
     +----+  | C-PE    A2-\                          | C-PE |  +----+
     +----+  |  1      A3--+--+              +---+---B2  2  |  +----+
     | CN2|--|         |   |PE+--------------+PE |---B3     |--| CN3|
     +----+  +---------+   +--+   trusted    +---+   +------+  +----+
                              |      WAN     |
     +----+  +---------+   +--+   packets    +---+   +------+  +----+
     | CN1|--|         C1--|PE| go natively  |PE |-- D1     |--| CN1|
     +----+  | C-PE    C2--+--+ without encry+---+   | C-PE |  +----+
             |  3      |      +--------------+       |  4   |
             |         |                             |      |
     +----+  |         |      without encrypt over   |      |  +----+
     | CN2|--|         C3--+---- Untrusted  --+------D2     |--| CN2|
     +----+  +---------+                             +------+  +----+

     CN: Client Network
                         Figure 1: Hybrid SDWAN



   Using C-PE2 for illustration, C-PE2 needs to send out two separate
   BGP UPDATE messages.

   BGP UPDATE #1 is to propagate C-PE2 attached routes, which are the
   regular VPN (L3VPN or EVPN) BGP Route UPDATE message,

      MP-NLRI Path Attribute



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         Nexthop (C-PE2)
         NLRI
          10.1.x.x.
          VLAN 15
          12.1.1x
      Tunnel-Encap Path Attribute
          Details of any tunnels that applicable to the routes carried
          by the MP-NLRI Path Attribute

   BGP UPDATE #2 is to propagate C-PE2's WAN port properties to RR,
   which should include:

        - Identifier for the WAN Port
        - The NAT property for the WAN Port
        - The minimum IPsec information for establishing Port based
           IPsec.

   Separating WAN port properties UPDATE from client routes UPDATE
   makes the implementation simpler, because the properties of a SDWAN
   node's WAN Port can change independent from the client routes
   attached to the C-PE2. WAN port properties change can be caused by
   many factors, such as ISP service agreement changes for the service
   connected to the WAN Port, the WAN port being disabled, or its IPsec
   property changes, etc.  Since most SDWAN edges only have a small
   number of WAN ports, the disadvantage of multiple BGP UPDATE
   messages to advertise properties of those WAN ports is relatively
   small.

   Following the same approach used by [idr-segment-routing-te-policy]
   where the SR Policy identifier is encoded in the MP-NLRI Path
   Attribute and the detailed SR Polices are encoded in the Tunnel Path
   attribute, the BGP UPDATE for SDWAN WAN port can have the WAN Port
   identifier encoded in the MP-NLRI Path Attribute and the associated
   WAN Port properties encoded in the Tunnel Path Attribute.

   Receivers of the UPDATE can associate the SDWAN node identifier,
   site identifier with the node's WAN Port properties.







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 2.2. SAFI under the MP-NLRI

   It is possible to continue using the same IP SAFI in the MP-NLRI
   [RFC4760] Path Attribute for advertising the SDWAN WAN port
   properties. If the same IP SAFI used, receiver needs extra logic to
   differentiate regular BGP MP-NLRI routes advertisement from the
   SDWAN WAN port properties advertisement and recognize the extra Site
   ID field added to the MP-NLRI. The benefit of using the same IP SAFI
   is that the UPDATE can traverse existing routers without being
   dropped. However, the SDWAN UPDATE is only between SDWAN edge and
   the RR, all the intermediate nodes treat the UPDATE message as
   regular IP data frame.

   That is why it is simpler to follow the same approach used by [idr-
   segment-routing-te-policy] to have a unique SAFI (IANA assigned
   SDWAN SAFI = 74) mainly to differentiate the SDWAN UPDATE from
   regular route UPDATE.

   This SDWAN SAFI is for a scenario where one SDWAN edge node has
   multiple WAN ports, some of which connected to private networks and
   others connected to public untrusted networks [Scenario #2 described
   in the [SDWAN-BGP-USAGE]]. The same routes attached to the SDWAN can
   be reached by the private networks without encryption (for better
   performance) or by the public networks with encryption.



 2.3. How about a new Path Attribute under BGP UPDATE?

   It is also possible to have a new Path Attribute, say SDWAN Path
   Attribute, combined with Tunnel Path Attribute to advertise SDWAN
   WAN Port properties. Besides having a different Path Attribute ID,
   everything else is same as using MP-NLRI & Tunnel Path Attributes.



3. SDWAN WAN Port Identifer encoding in the MP-NLRI Path Attribute

   SDWAN WAN Port Identifier needs the following attributes

        - locally significant port number,
        - the location of the SDWAN device, and
        - the globally routable address for the WAN Port.




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   Here is the encoding for those attributes in the NLRI field within
   the MP_REACH_NLRI Path Attribute of RFC4760, under a SDWAN SAFI
   (code = 74):



   +------------------+
   |   NLRI Length    | 1 octet
   +------------------+
   |   SDWAN-Type     | 2 Octets
   +------------------+
   |   Port-Local-ID  | 4 octets
   +------------------+
   |  SDWAN-Site-ID   | 4 octets
   +------------------+
   |  SDWAN-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 SDWAN
       NLRI. There could be different sub-TLVs for different SDWAN WAN
       ports and their associated policies.
     - Port local ID: SDWAN edge node Port identifier, which can be
       locally significant. Each port can have unique 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 subTLVs, e.g. Port-subTLV under the Tunnel Path Attribute.

     - SDWAN-Site-ID: used to identify a common property shared by a
       set of SDWAN edge nodes, such as the property of a specific
       geographic location shared by a group of SDWAN edge nodes. The
       property is used to steer an overlay route to traverse specific
       geographic locations for various reasons, such as to comply



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       regulatory rules, to utilize specific value added services, or
       others.
     - SDWAN EdgeNode ID: the SDWAN edge node identifier, which has to
       be a routable address (IPv4 or IPv6) within the WAN.

4. WAN Port Properties encoding in the Tunnel Path Attribute

   The content of the SDWAN Port properties is encoded in the Tunnel
   Encapsulation Attribute defined in [Tunnel-Encap] using a new
   Tunnel-Type TLV (code point to be assigned by IANA from the "BGP
   Tunnel Encapsulation Attribute Tunnel Types" registry).

   Tunnel Encaps Path Attribute (Code = 23)

     Tunnel Type: SDWAN-WAN-Port
     Followed by the detailed properties encoded as subTLV, such as
          SubTLV for NAT
          SubTLV for IPsec-SA Attribute
          SubTLV for ISP connected to 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(=SDWAN-WAN-Port )| Length (2 Octets)              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                             Value                             |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
           SDWAN Tunnel Encapsulation TLV Value Field

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








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4.1. Port Ext SubTLV for NAT

      NAT information is encoded is the Port Ext sub-TLV is for
      describing the NAT property if the port has private address and
      the network identifier to which the WAN port is connected, etc.

      A SDWAN 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.



        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |Port Ext 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 Port Ext Type: indicate it is the Port Ext SubTLV.
     o PortExt subTLV Length: the length of the subTLV.
     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.



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             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).
     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 SDWAN edge 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.

4.2. IPsec Security Association Property

     The IPsecSA sub-TLV is for the SDWAN edge node to establish IPsec
     security association with their peers via the port that face
     untrusted network. The minimum set of the IPsec information is
     from [CONTROLLER-IKE].

        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         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         Key Counter                                           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | key1 length   |         Public Key                            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | key2 length   |         Nonce                                 |



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       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | key3 length   |    key3 (for potential other keys             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |        Duration                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Where:

     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
        SDWAN edge 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
        SDWAN edge node can have multiple authentication algorithms;
        send to its peers to negotiate the strongest one. Default
        algorithm is AES-256.
     o Rekay Counter: 4 bytes
     o Public Key: IPsec public key
     o Nonce.IPsec Nonce
     o Key3.other potential key
     o Duration: SA life span.

4.3. Remote Endpoint

   The Remote Endpoint sub-TLV is not used for SDWAN NLRI because
     o The SDWAN Node ID and Site ID are already encoded in the SDWAN
        NLRI,
     o The network connected by the SDWAN WAN port might have
        identifier that is more than the AS number. SDWAN controller
        might use its own specific identifier for the network.


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     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 edge nodes.


5. Manageability Considerations

      TBD - this needs to be filled out before publishing

6. Security Considerations

     The document describes the encoding for SDWAN edge nodes to
     advertise its SDWAN WAN ports properties to their peers via
     untrusted & unsecure networks.

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

    [More details need to be filled in here]


7. IANA Considerations

   This document requires the following IANA actions.

       o SDWAN Overlay SAFI = 74 assigned by IANA
       o SDWAN Route Type

8. References


     8.1. Normative References

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






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     8.2. 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.

   [CONTROLLER-IKE] D. Carrel, et al, "IPsec Key Exchange using a
             Controller", draft-carrel-ipsecme-controller-ike-01, work-
             in-progress.

   [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.

   [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.


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



9. Acknowledgments

   Acknowledgements to Wang Haibo, Hao Weiguo, and ShengCheng for
   implementation contribution; Many thanks to Jim Guichard, John
   Scudder, Darren Dukes, Andy Malis, Rachel Huang 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
   Futurewei
   Email: ldunbar@futurewei.com

   Sue Hares
   Hickory Hill Consulting
   Email: shares@ndzh.com





































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