Imported debug from /usr/lib/site-python/debug.pyc draft-dm-net2cloud-gap-analysis-04 - Gap Analysis of Interconnecting Underlay with Cloud Overlay
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Versions: (draft-dm-vpn-ext-to-cloud-dc-gap-analysis) 00 01 02 03 04 draft-ietf-rtgwg-net2cloud-gap-analysis

Network Working Group                                         L. Dunbar
Internet Draft                                                 A. Malis
Intended status: Informational                                   Huawei
Expires: August 6, 2019                                    C. Jacquenet
                                                                  Orange
                                                       February 6, 2019



        Gap Analysis of Interconnecting Underlay with Cloud Overlay
                    draft-dm-net2cloud-gap-analysis-04

Abstract

   This document analyzes the technological gaps when using SD-WAN to
   interconnect workloads & apps hosted in various locations,
   especially cloud data centers when the network service providers do
   not have or have limited physical infrastructure to reach the
   locations [Net2Cloud-problem].

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
   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

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html

   This Internet-Draft will expire on July 6, 2019.



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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
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document. Please review these documents
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   warranty as described in the Simplified BSD License.

Table of Contents


   1. Introduction...................................................2
   2. Conventions used in this document..............................3
   3. Gap Analysis of C-PEs Registration Protocol....................4
   4. Gap Analysis in aggregating VPN paths and Internet paths.......5
      4.1. Gap analysis of Using BGP to cover SD-WAN paths...........6
      4.2. Gaps in preventing attacks from Internet facing ports.....9
   5. Gap analysis of CPEs not directly connected to VPN PEs........10
      5.1. Gap Analysis of Floating PEs to connect to Remote CPEs...11
      5.2. NAT Traversal............................................12
      5.3. Complication of using BGP between PEs and remote CPEs via
      Internet......................................................12
      5.4. Designated Forwarder to the remote edges.................13
      5.5. Traffic Path Management..................................13
   6. Manageability Considerations..................................14
   7. Security Considerations.......................................14
   8. IANA Considerations...........................................14
   9. References....................................................14
      9.1. Normative References.....................................15
      9.2. Informative References...................................15
   10. Acknowledgments..............................................16

1. Introduction

   [Net2Cloud-Problem] describes the problems that enterprises face
   today in transitioning their IT infrastructure to support digital


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   economy, such as connecting enterprises' branch offices to dynamic
   workloads in different Cloud DCs.

   This document analyzes the technological gaps to interconnect
   dynamic workloads & apps hosted in various locations and in Cloud
   DCs that the enterprise existing VPN service provider might not have
   or have limited the physical infrastructure to reach. When
   enterprise' VPN service providers do not have or have insufficient
   bandwidth to reach a location, SD-WAN is emerged as way to aggregate
   bandwidth of multiple networks, such as MPLS VPN, Public Internet,
   etc. This document primarily focuses on the technological gaps of
   SD-WAN.

   For ease of description, SD-WAN edge, SD-WAN end points, C-PE, or
   CPE are used interchangeably throughout this document.



2. Conventions used in this document

   Cloud DC:   Third party 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.

   OnPrem:     On Premises data centers and branch offices

   SD-WAN:     Software Defined Wide Area Network. In this document,
               "SD-WAN" refers to the solutions specified by ONUG (Open
               Network User Group), https://www.onug.net/software-
               defined-wide-area-network-sd-wan/, which is about
               pooling WAN bandwidth from multiple underlay networks to
               get better WAN bandwidth management, visibility &
               control. When the underlay networks are private


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               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. Gap Analysis of C-PEs Registration Protocol

   SD-WAN, conceived in ONUG (Open Network User Group) a few years ago
   as a means to aggregate multiple connections between any two points,
   has emerged as an on-demand technology to securely interconnect the
   OnPrem branches with the workloads instantiated in Cloud DCs that do
   not connect to BGP/MPLS VPN PEs or have very limited bandwidth.

   Some SD-WAN networks use the NHRP protocol [RFC2332] to register SD-
   WAN edges with a "Controller" (or NHRP server), which then has the
   ability to map a private VPN address to a public IP address of the
   destination node. DSVPN [DSVPN] or DMVPN [DMVPN] are used to
   establish tunnels among SD-WAN edge nodes.

   NHRP was originally intended for ATM address resolution, and as a
   result, it misses many attributes that are necessary for dynamic
   endpoint C-PE registration to controller, such as:

   - Interworking with MPLS VPN control plane. A SD-WAN edge can have
     some ports facing MPLS VPN network and some ports facing public
     Internet that requires encryption for some sensitive data to
     traverse.
   - Scalability. NHRP/DSVPN/DMVPN works fine with small number of edge
     nodes. When a network has more than 100 nodes, the protocol does
     not work well.
   - NHRP does not have the IPsec attributes, which are needed for peers to
     build Security Associations over public internet.
   - NHRP does not have field to indicate C-PE supported encapsulation types,
     such as IPsec-GRE, IPsec-VxLAN, or others.
   - NHRP does not have field to indicate C-PE Location identifier, such as
     Site Identifier, System ID, and/or Port ID.
   - NHRP does not have field to describe the gateway to which the C-PE
     is attached. When a C-PE is instantiated in a Cloud DC, to




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     establish connection to the C-PE, it is necessary to know the
     Cloud DC operator's Gateway to which the CPE is attached.
   - NHRP does not have field to describe C-PE's NAT properties if the
     C-PE is using private addresses, such as the NAT type, Private
     address, Public address, Private port, Public port, etc.


   [BGP-SDWAN-EXT] describes how to use BGP for SD-WAN edge nodes to
   register its properties to SD-WAN controller, which then
   disseminates the information to other SD-WAN edge nodes that are
   authenticated to communicate.

4. Gap Analysis in aggregating VPN paths and Internet paths

   Most likely, enterprises especially large ones already have their
   CPEs interconnected by providers' VPNs, such as EVPN, L2VPN, or
   L3VPN. The VPN can be PE based or CPE based as shown in the
   following diagram. The commonly used CPE-based VPNs have CPE
   directly attached to PEs, therefore the communication is considered
   as secure. BGP are used to distribute routes among CPEs, even though
   sometimes routes among CPEs are statically configured.
                              +---+ EVPN MAC/IP BGP updates
                       +======+RR +===========+
                      //      +---+           \\
                     //                        \\
                    //  <-----EVPN-VxLAN------> \\
                  +-+--+  ++-+        ++-+    +--+-+
                  | CPE|--|PE|        |PE+----+ CPE|
                  |  1 |  |1 |        |x |    | x  |
                  +-+--+  ++-+        ++-+    +----+
                           |           |
                           |  VPN    +-+---+    +----+
                           | Network | PE3 |    |CPE |
                           |         |     |- --| 3  |
          +--------+    +--+--+      +-+---+    +----+
          | CPE    +----+ PE4 |--------+
          |  4     |    +---+-+
          +--------+

         === or \\ indicates control plane communications

                      Figure 1: L2 or L3 VPNs over IP WAN






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   To use SD-WAN to aggregate Internet routes with the VPN routes, the
   C-PEs need to have some ports connected to PEs and other ports
   connected to the Internet. It is necessary to have a registration
   protocol for C-PEs to register with their SD-WAN Controllers to
   establish secure tunnels among relevant C-PEs.

   If using NHRP for registration, C-PEs need to participate in two
   separate control planes: EVPN&BGP for CPE-based VPNs via links
   directly attached to PEs and NHRP & DSVPN/DMVPN for ports connected
   to internet. Two separate control planes not only add complexity to
   C-PEs, but also increase operational cost.


               +---------Internet paths--------------+
               |                                     |
               |              +---+                  |
               |              |RR |                  |
               |       +======+---+===========+      |
               |     //                      \\      |
               |    //  <-----EVPN-VxLAN----> \\     |
               |  +-+--+  ++-+        ++-+  +--+-+  (|)
               |  | CPE|--|PE|        |PE+--+ CPE|  (|)
               +--|  1 |  |1 |        |x |  | c  |---+
                  +-+--+  ++-+        ++-+  +----+
                           |           |
                           |  VPN    +-+---+    +----+
          +--------+       | Network | PE3 |    |CPE |
          | CPE    |       |         |     |- --| 3  |
          |   c    |       +-----+   +-+---+    +----+
          +------+-+-------+ PE4 |-----+
                           +---+-+
            Figure 2: CPEs interconnected by VPN paths and Internet Paths


 4.1. Gap analysis of Using BGP to cover SD-WAN paths

   Since C-PE already supports BGP, it is desirable to consider using
   BGP to control the SD-WAN instead of two separate control planes.
   This section analyzes the gaps of using BGP to control SD-WAN.

   As described [BGP-SDWAN-Usage], SD-WAN Overlay Control Plane has
   three distinct functional tiers:

     - SD-WAN node's private address and WAN Ports/Addresses
        registration to the SD-WAN Controller.


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          o It is for informing the SD-WAN controller and potential
             peers of the underlay networks to which the C-PE is
             connected.

     - Controller Facilitated IPsec SA management and NAT information
        distribution
          o It is for SD-WAN controller to facilitate or manage the
             IPsec configurations and peer authentications for all
             IPsec tunnels terminated at the SDWAN nodes. For some
             scenarios where the WAN ports are private addresses, this
             step is for informing the type of NAT translating the
             private addresses to public ones.

     - Establishing and Managing the topology and reachability for
        services attached to the client ports of SD-WAN nodes.
          o This is for the overlay layer's routes distribution, so
             that a C-PE can establish the overlay routing table that
             identifies the next hop for reaching a specific
             route/service attached to remote nodes. [SECURE-EVPN]
             describes EVPN and other options.


   RFC5512 and [Tunnel-Encap] describe methods for endpoints to
   advertise tunnel information and to trigger tunnel establishment.
   RFC5512 & [Tunnel-Encap] have the Endpoint Address to indicate IPv4
   or IPv6 address format, the Tunnel Encapsulation attribute to
   indicate different encapsulation formats, such as L2TPv3, GRE,
   VxLAN, IP-in-IP, etc. There are sub-TLVs to describe the detailed
   tunnel information for each of the encapsulations.

   [Tunnel-Encap] removed SAFI =7 (which was specified by RFC5512) for
   distributing encapsulation tunnel information. [Tunnel-Encap]
   require Tunnels being associated with routes.

   There is also the Color sub-TLV to describe customer-specified
   information about the tunnels (which can be creatively used for SD-
   WAN)

   Here are some of the gaps using [Tunnel-Encap] to control SD-WAN:

   - Lacking C-PE Registration functionality
   - Lacking IPsec Tunnel type




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   - [Tunnel-Encap] has Remote Address SubTLV, but does not have any
     field to indicate the Tunnel originating interface, which was in
     RFC5512.
   - The mechanisms described by [Tunnel-Encap] cannot be effectively
     used for SD-WAN overlay network because a SD-WAN Tunnel can be
     between Internet facing WAN ports of two C-PEs and needs to be
     established before data arrival because the tunnel establishment
     can fail, e.g. two end points supporting different encryption
     algorithms.
   - Client traffic (e.g. an EVPN route) can have option of going
     through MPLS network natively without encryption, or going through
     the IPsec tunnels between the internet facing WAN ports of two C-
     PEs.
   - There is no routes to be associated with the SD-WAN Tunnel between
     two C-PE's internet facing WAN ports, unless consider using the
     interface facing WAN Port addresses assigned by ISP (Internet
     Service Providers) as the route for the Tunnel.
     There is a suggestion on using a "Fake Route" for a SD-WAN node to
     use [Tunnel-Encap] to advertise its SD-WAN tunnel end-points
     properties. However, using "Fake Route" can create deployment
     complexity for large SD-WAN networks with many tunnels. For
     example, for a SD-WAN network with hundreds of nodes, with each
     node having many ports & many end-points to establish SD-WAN
     tunnels to their corresponding peers, the node would need many
     "fake addresses". For large SD-WAN networks (such as has more than
     10000 nodes), each node might need 10's thousands of "fake
     addresses", which is very difficult to manage and needs lots of
     configuration to get the nodes provisioned.
   - Does not have fields to carry detailed information of the remote
     C-PE: such as Site-ID, System-ID, Port-ID
   - Does not have the proper field to express IPsec attributes among
     the SD-WAN edge nodes to establish proper IPsec Security
     Associations.
   - Does not have proper way for two peer CPEs to negotiate IPSec
     keys, based on the configuration sent by the Controller.
   - Does not have field to indicate the UDP NAT private address <->
     public address mapping
   - C-PEs tend to communicate with a few other CPEs, not all the C-PEs
     need to form mesh connections.  Without any BGP extension, many




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     nodes can get dumped with too much information of other nodes that
     they never need to communicate with.


   [VPN-over-Internet] describes a way to securely interconnect C-PEs
   via IPsec using BGP. This method is useful, however, it still misses
   some aspects to aggregate CPE-based VPN routes with internet routes
   that interconnect the CPEs. In addition:

   - The draft does not have options of C-PE having both MPLS ports and
     Internet ports.
   - The draft assumes that CPE "registers" with the RR. However, it does not
     say how. It assumes that the remote CPEs are pre-configured with the
     IPsec SA manually. In SD-WAN, Zero Touch Provisioning is expected. It is
     not acceptable to require manual configuration.
   - For RR communication with CPE, this draft only mentioned IPSec. Missing
     TLS/DTLS.
   - The draft assumes that CPEs and RR are connected with an IPsec tunnel.
     With zero touch provisioning, we need an automatic way to synchronize
     the IPsec SA between CPE and RR. The draft assumes:
          A CPE must also be provisioned with whatever additional information
          is needed in order to set up an IPsec SA with each of the red RRs

   - IPsec requires periodic refreshment of the keys. The draft hasn't
     addressed how to synchronize the refreshment among multiple nodes.
   - IPsec usually only sends configuration parameters to two endpoints
     and let the two endpoints negotiate the KEY. Now we assume that RR
     is responsible for creating the KEY for all endpoints. When one
     endpoint is compromised, all other connections are impacted.


 4.2. Gaps in preventing attacks from Internet facing ports

   When C-PEs have ports facing Internet, it brings in the security
   risks of potential DDoS attacks to the C-PEs from the ports facing
   internet.

   To mitigate security risks, in addition to requring Anti-DDoS
   features on C-PEs to prevent major DDoS attacks, it is necessary to
   have ways for C-PEs to validate traffic from remote peers to prevent
   spoofed traffic.






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5. Gap analysis of CPEs not directly connected to VPN PEs

   Because of the ephemeral property of the selected Cloud DCs, an
   enterprise or its network service provider may not have the direct
   links to the Cloud DCs that are optimal for hosting the enterprise's
   specific workloads/Apps. Under those circumstances, SD-WAN is a very
   flexible choice to interconnect the enterprise on-premises data
   centers & branch offices to its desired Cloud DCs.

   However, SD-WAN paths over public Internet can have unpredictable
   performance, especially over long distances and across domains.
   Therefore, it is highly desirable to place as much as possible the
   portion of SD-WAN paths over service provider VPN (e.g.,
   enterprise's existing VPN) that have guaranteed SLA to minimize the
   distance/segments over public Internet.

   MEF Cloud Service Architecture [MEF-Cloud] also describes a use case
   of network operators needing to use SD-WAN over LTE or public
   Internet for last mile accesses where they are not present.

   Under those scenarios, one or both of the SD-WAN endpoints may not
   directly be attached to the PEs of a VPN Domain.

   Using SD-WAN to connect the enterprise existing sites with the
   workloads in Cloud DC, the enterprise existing sites' CPEs have to
   be upgraded to support SD-WAN.  If the workloads in Cloud DC need to
   be connected to many sites, the upgrade process can be very
   expensive.

   [Net2Cloud-Problem] describes a hybrid network approach that
   integrates SD-WAN with traditional MPLS-based VPNs, to extend the
   existing MPLS-based VPNs to the Cloud DC Workloads over the access
   paths that are not under the VPN provider control. To make it work
   properly, a small number of the PEs of the MPLS VPN can be
   designated to connect to the remote workloads via SD-WAN secure
   IPsec tunnels.  Those designated PEs are shown as fPE (floating PE
   or smart PE) in Figure 3. Once the secure IPsec tunnels are
   established, the workloads in Cloud DC can be reached by the
   enterprise's VPN without upgrading all of the enterprise's existing
   CPEs. The only CPE that needs to support SD-WAN would be a
   virtualized CPE instantiated within the cloud DC.


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   +--------+                                             +--------+
   | Host-a +--+                                     +----| Host-b |
   |        |  |                                    (')   |        |
   +--------+  |           +-----------+           (   )  +--------+
               |  +-+--+  ++-+        ++-+  +--+-+  (_)
               |  | CPE|--|PE|        |PE+--+ CPE|   |
               +--|    |  |  |        |  |  |    |---+
                  +-+--+  ++-+        ++-+  +----+
                   /       |           |
                  /        |  MPLS   +-+---+    +--+-++--------+
          +------+-+       | Network |fPE-1|    |CPE || Host   |
          | Host   |       |         |     |- --|    ||   d    |
          |   c    |       +-----+   +-+---+    +--+-++--------+
          +--------+       |fPE-2|-----+
                           +---+-+    (|)
                              (|)     (|) SD-WAN
                              (|)     (|) over any access
                              +=\======+=========+
                             //   \    | Cloud DC \\
                            //      \ ++-----+       \\
                                      +Remote|
                                      |  CPE |
                                      +-+----+
                            ----+-------+-------+-----
                                |               |
                            +---+----+      +---+----+
                            | Remote |      | Remote |
                            | App-1  |      | App-2  |
                            +--------+      +--------+

                    Figure 3: VPN Extension to Cloud DC

   In Figure 3, the optimal Cloud DC to host the workloads (due to
   proximity, capacity, pricing, or other criteria chosen by the
   enterprises) does not happen to have a direct connection to the PEs
   of the MPLS VPN that interconnects the enterprise's existing sites.


5.1. Gap Analysis of Floating PEs to connect to Remote CPEs

   To extend MPLS VPNs to remote CPEs, it is necessary to establish
   secure tunnels (such as IPsec tunnels) between the Floating PEs and
   the remote CPEs.

   Gap:


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   Even though a set of PEs can be manually selected to act as the
   floating PEs for a specific cloud data center, there are no standard
   protocols for those PEs to interact with the remote CPEs (most
   likely virtualized) instantiated in the third party cloud data
   centers (such as exchanging performance or route information).

   When there is more than one fPE available for use (as there should
   be for resiliency or the ability to support multiple cloud DCs
   scattered geographically), it is not straightforward to designate an
   egress fPE to remote CPEs based on applications.  There is too much
   applications' traffic traversing PEs, and it is not feasible for PEs
   to recognize applications from the payload of packets.


5.2. NAT Traversal

   Most cloud DCs only assign private addresses to the workloads
   instantiated. Therefore, traffic to/from the workload usually need
   to traverse NAT.
   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.

5.3. Complication of using BGP between PEs and remote CPEs via Internet

   Even though an EBGP (external BGP) Multi-hop design can be used to
   connect peers that are not directly connected to each other, there
   are still some complications/gaps in extending BGP from MPLS VPN PEs
   to remote CPEs via any access paths (e.g., Internet).

   The path between the remote CPEs and VPN PE can traverse untrusted
   nodes.

   EBGP Multi-hop scheme requires static configuration on both peers.
   To use EBGP between a PE and remote CPEs, the PE has to be manually
   configured with the "next-hop" set to the IP addresses of the CPEs.
   When remote CPEs, especially remote virtualized CPEs are dynamically
   instantiated or removed, the configuration on the PE Multi-Hop EBGP
   has to be changed accordingly.

   Gap:


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     Egress peering engineering (EPE) is not enough. Running BGP on
     virtualized CPEs in Cloud DC requires GRE tunnels being
     established first, which in turn requires address and key
     management for the remote CPEs. RFC 7024 (Virtual Hub & Spoke) and
     Hierarchical VPN is not enough.

     Also there is a need for a method to automatically trigger
     configuration changes on PE when remote CPEs' are instantiated or
     moved (leading to an IP address change) or deleted.

     EBGP Multi-hop scheme does not have an embedded security
     mechanism. The PE and remote CPEs need secure communication
     channels when connecting via the public Internet.

   Remote CPEs, if instantiated in Cloud DC, might have to traverse NAT
   to reach PE. It is not clear how BGP can be used between devices
   outside the NAT and the entities behind the NAT. It is not clear how
   to configure the Next Hop on the PEs to reach private IPv4
   addresses.




5.4. Designated Forwarder to the remote edges

   Among multiple floating PEs available for a remote CPE, multicast
   traffic from the remote CPE towards the MPLS VPN can be forwarded
   back to the remote CPE due to the PE receiving the multicast data
   frame forwarding the multicast/broadcast frame to other PEs that in
   turn send to all attached CPEs. This process may cause traffic loop.

   Therefore, it is necessary to designate one floating PE as the CPE's
   Designated Forwarder, similar to TRILL's Appointed Forwarders
   [RFC6325].

   Gap: the MPLS VPN does not have features like TRILL's Appointed
   Forwarders.

5.5. Traffic Path Management

   When there are multiple floating PEs that have established IPsec
   tunnels to the remote CPE, the remote CPE can forward the outbound
   traffic to the Designated Forwarder PE, which in turn forwards the



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   traffic to egress PEs to the destinations. However, it is not
   straightforward for the egress PE to send back the return traffic to
   the Designated Forwarder PE.

   Example of Return Path management using Figure 3 above.

   - fPE-1 is DF for communication between App-1 <-> Host-a due to
   latency, pricing or other criteria.
   - fPE-2 is DF for communication between App-1 <-> Host-b.



6. Manageability Considerations

      Zero touch provisioning of SD-WAN edge nodes is expected in SD-
     WAN deployment. It is necessary for a newly powered up SD-WAN
     edges to establish a secure connection (such as TLS, DTLS, etc.)
     to its controller.

7. Security Considerations

     The intention of this draft is to identify the gaps in current and
     proposed SD-WAN approaches that can address requirements
     identified in [Net2Cloud-problem].

     Several of these approaches have gaps in meeting enterprise
     security requirements when tunneling their traffic over the
     Internet, as is the general intention of SD-WAN. See the
     individual sections above for further discussion of these security
     gaps.


8. IANA Considerations

   This document requires no IANA actions. RFC Editor: Please remove
   this section before publication.

9. References





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 9.1. Normative References

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

 9.2. 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.

   [BGP-SDWAN-EXT]L. Dunbar, "BGP Extension for SDWAN Overlay
             Networks", draft-dunbar-idr-bgp-sdwan-overlay-ext-00, Oct
             2018.

   [BGP-SDWAN-Usage] L. Dunbar, et al, "Framework of Using BGP for
             SDWAN Overlay Networks", draft-dunbar-idr-sdwan-framework-
             00, work-in-progress, Feb 2019.

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







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   [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



10. Acknowledgments

   Acknowledgements to xxx for his 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

   Andrew G. Malis
   Huawei
   Email: agmalis@gmail.com

   Christian Jacquenet
   Orange
   Rennes, 35000
   France
   Email: Christian.jacquenet@orange.com































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