Corresponding Gateway Exchange in Multi-segment SD-WAN

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Table of Contents

1. Introduction

[I-D.draft-dmk-rtgwg-multisegment-sdwan] describes the enterprises utilizing Cloud Providers’ backbone to interconnect their branch offices. As shown in Figure 1, CPE-1 and CPE-2 are connected to their respective Cloud Gateways (GW) in different regions. CPE-1 and CPE-2 maintain the pairwise IPsec SAs. The IPsec encrypted traffic from CPE-1 to CPE-2 is encapsulated by the GENEVE header [RFC8926], with the outer destination address being the GW1. [I-D.draft-dmk-rtgwg-multisegment-sdwan] specifies a set of sub-TLVs to carry the information of the GWs of the destination branches, e.g., GW3 for CPE-2 and other attributes.¶

To accomplish that, CPE-1 needs to know their peers' corresponding GW addresses. This document proposes a BGP extension based on [I-D.draft-ietf-idr-sdwan-edge-discovery] for a CPE to advertise its directly connected GW address to other CPEs.¶

  (^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^)
  (            Region2             )
  (            +-----+             )
  (            | GW2 |             )
  (            +-----+             )
  (           /       \            )
  (          /  Cloud  \           )
  (         /  Backbone \          )
  ( Region1/             \Region3  )
  ( +-----+               +-----+  )
  ( | GW1 |---------------| GW3 |  )
  ( +--+--+               +--+--+  )
  (^^^^|^^^^^^^^^^^^^^^^^^^^^|^^^^^)
       |                     |
    +--+--+               +--+--+
    |CPE 1|               |CPE 2|
    +-----+               +-----+

2. 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.¶

The following acronyms and terms are used in this document:¶

• Cloud DC: Off-Premises Data Center, managed by 3rd party, that hosts applications, services, and workload for different organizations or tenants.¶
• CPE: Customer (Edge) Premises Equipment.¶
• OnPrem: On Premises data centers and branch offices.¶
• RR Route Reflector.¶
• SD-WAN: Software Defined Wide Area Network. In this document, “SD-WAN” refers to a policy-driven transporting of IP packets over multiple underlay networks for better WAN bandwidth management, visibility, and control.¶
• VPN Virtual Private Network.¶

3. Extension to SD-WAN Underlay UPDATE for Corresponding GWs

The Client Routes Update is the same as described in Section 5 of [I-D.draft-ietf-idr-sdwan-edge-discovery].¶

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Type=TBD    |    length     |  reserved     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Corresponding GW Addr Family  | Address                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ (variable)                    +
   ~                                                               ~
   |             Corresponding GW Address                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

4. Security Considerations

This document does not introduce any new security considerations.¶

5. IANA Considerations

TBD.¶

Authors' Addresses