Just finished reading your draft and I don’t think the two drafts are 
complimentary. Frankly, I don’t see any advantages for using a separate SAFI 
for this purpose but many disadvantages such as:


  1.  Resurrecting the approach in RFC 5512 that is being deprecated – i.e., 
send a separate route for the tunnel and then color the other routes to 
associated with the tunnel (using indirection) and opposed the current common 
practice in Tunnel Encap attribute that sends the attribute directly with the 
corresponding route.
  2.  When establishing IPsec tunnel at a more granular level (e.g., per pair 
of VPN MAC or IP addresses), you need to advertise twice as many routes !!
  3.  The overhead associated with a new SAFI as opposed to use exiting 
attribute
  4.  NAT can be handled without the new SAFI

The secure tunnel between each PE and the RR (e.g., IPsec) for the BGP session 
is common between the two drafts as mentioned first by the controller-ike 
draft. This is needed because you want to make sure that the BGP session goes 
over a tunnel that is authenticated between the peers (and encrypted). 
Intuitively the use of tunnel encap attribute for IPsec should be clear as 
IPsec is another tunnel type and key exchange parameter, transfer function, DH 
groups, etc. are attributes/properties of such tunnel and thus to be advertised 
in this new tunnel type TLV.

Let’s start with EVPN because that is the technology/solution being used 
predominately in DCs, DCIs, and enterprise inter-site connectivity. I listed 
the disadvantages of using a separate SAFI above, can you list the advantages 
of using a separate SAFI for EVPN?

Cheers,
Ali

From: BESS <bess-boun...@ietf.org> on behalf of Linda Dunbar 
<linda.dun...@huawei.com>
Date: Tuesday, October 30, 2018 at 9:19 AM
To: "i...@ietf.org" <i...@ietf.org>, "bess@ietf.org" <bess@ietf.org>
Subject: [bess] Comparing using the SD-WAN Overlay SAFI specified by 
draft-dunbar-idr-bgp-sdwan-overlay-ext with the EVPN approach described by 
draft-sajassi-bess-secure-evpn-00

IDR group, BESS group,

https://datatracker.ietf.org/doc/draft-dunbar-idr-bgp-sdwan-overlay-ext/ 
specifies a new BGP SAFI (=74) in order to advertise a SD-WAN edge node’s 
capabilities in establishing SD-WAN overlay tunnels with other SD-WAN nodes 
through third party untrusted networks.

draft-sajassi-bess-secure-evpn-00 describes an EVPN solution for PE nodes to 
exchange key and policy to create private pair-wise IPsec Security Associations 
without IKEv2 point-to-point signaling or any other direct peer-to-peer session 
establishment messages.

I think those two solutions are not conflicting with each other. Actually they 
are compliment to each other to some degree. For example,

  *   the Re-key mechanism described by draft-sajassi-bess-secure-evpn-00 can 
be utilized by draft-dunbar-idr-bgp-sdwan-overlay-ext
  *   The SD-WAN Overlay SAFI can be useful to simplify the process on RR to 
re-distribute the Tunnel End properties to authorized peers.
  *   When SD-WAN edge nodes use private address, or no IP address, NAT 
properties for the end points distribution described 
draft-dunbar-idr-bgp-sdwan-overlay-ext is necessary.
  *   The secure channel between SD-WAN edge nodes and RR described by 
draft-dunbar-idr-bgp-sdwan-overlay-ext is necessary.

Any thoughts?

Thank you very much.

Linda Dunbar
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