Darren,  Clarence, Gaurav, Xiaohu, Daniel, Pablo, and Francois,

Since your draft-dukes-spring-sr-for-sdwan-02 describes on how SR enables 
underlay SLA to Software-Defined WAN (SDWAN), we want to get your feedback on 
the 
https://datatracker.ietf.org/doc/draft-ietf-rtgwg-net2cloud-problem-statement/ 
which discusses the problems associated with using SD-WAN to interconnect 
Hybrid Cloud DCs. The draft focuses on the network problems that many 
enterprises face when they have workloads & applications & data split among 
different data centers, especially for those enterprises with multiple sites 
that are already interconnected by VPNs (e.g., MPLS L2VPN/L3VPN,, and/or SR).
Want your feedback on whether SD-WAN integrating with SR can solve some of the 
problems discussed in the draft?
SD-WAN interconnection of branch offices is not as simple as it appears. For an 
enterprise with multiple sites, using SD-WAN overlay paths among sites requires 
each CPE to manage all the addresses that local hosts have the potential to 
reach, i.e., map internal VPN addresses to appropriate SD-WAN paths. This is 
similar to the complexity of Frame Relay based VPNs, where each CPE needed to 
maintain mesh routing for all destinations if they were to avoid an extra hop 
through a hub router. Even though SD-WAN CPEs can get assistance from a central 
controller (instead of running a routing protocol) to resolve the mapping 
between destinations and SD-WAN paths, SD-WAN CPEs are still responsible for 
routing table maintenance as remote destinations change their attachments, 
e.g., the dynamic workload in other DCs are de-commissioned or added.
Even though originally envisioned for interconnecting branch offices, SD-WAN 
offers a very attractive way for enterprises to connect to Cloud DCs.
The SD-WAN for interconnecting branch offices and the SD-WAN for 
interconnecting to Cloud DCs have some differences:

  *   SD-WAN for interconnecting branch offices usually have two end-points 
(e.g., CPEs) controlled by one entity (e.g., a controller or management system 
operated by the enterprise).
  *   SD-WAN for Cloud DC interconnects may consider CPEs owned or managed by 
the enterprise, while remote end-points are being managed or controlled by 
Cloud DCs (For the ease of description, let's call such CPEs 
asymmetrically-managed CPEs).
  *   Cloud DCs may have different entry points (or devices) with one entry 
point that terminates a private direct connection (based upon a leased line for 
example) and other entry points being devices terminating the IPsec tunnels, as 
shown in Figure 2.

Thank you very much.
Linda Dunbar
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