Basil,

You asked a really good question "can you please explain how RFC8388 is used to 
learn the client prefixes in this scenario?"

SDWAN services to clients can be IP based or Ethernet based. RFC8388 has 
specified necessary parameters to be configured for Ethernet based services to 
clients. For IP based services, clients routes can be learned via OSPF, RIP, 
BGP or statically configuration. The mapping from clients routes to SDWAN 
Segmentation Identifier have to be configured.

Do you think the following description is clear enough?
"SDWAN services to clients can be IP based or Ethernet based. For IP based 
services, an SDWAN node can learn client routes from the client facing ports 
via OSPF, RIP, BGP or Statically configuration. If the SDWAN services are layer 
2 services, the relevant EVPN parameters, such as the ESI (Ethernet Segment 
Identifier), EVI, CE-VID to EVI mapping have to be configured in the same way 
as EVPN described in RFC8388. "


The CNx in Figure 2 represents a Client Network.  Some CN can be multi-homed to 
two PEs (which is not shown in the figure for -02 revision, will be updated for 
-03 revision).

Linda Dunbar

From: Najem, Basil <basil.na...@bell.ca>
Sent: Wednesday, January 27, 2021 9:19 PM
To: Linda Dunbar <linda.dun...@futurewei.com>; bess@ietf.org
Subject: RE: Is there any issue with the changes to the Packet Walk-Through for 
BGP SDWAN usage ?

Dear Linda;

Is CNx in Figure 2 represents a distinct IP prefix? If yes, this must be added 
to the description.

The SD-WAN node can learn the local client's prefixes (i.e. the client prefixes 
that are connected directly to the node) via a routing protocol (e.g. OSPF, 
BGP); can you please explain how RFC8388 is used to learn the client prefixes 
in this scenario? More explanation is warranted here.

Regards;

Basil
From: BESS <bess-boun...@ietf.org<mailto:bess-boun...@ietf.org>> On Behalf Of 
Linda Dunbar
Sent: January-27-21 12:09 PM
To: bess@ietf.org<mailto:bess@ietf.org>
Subject: [EXT][bess] Is there any issue with the changes to the Packet 
Walk-Through for BGP SDWAN usage ?

BESS WG:

We recently made some changes to the Packet Walk-Through for BGP SDWAN usage 
https://datatracker.ietf.org/doc/draft-ietf-bess-bgp-sdwan-usage/<https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fdraft-ietf-bess-bgp-sdwan-usage%2F&data=04%7C01%7Clinda.dunbar%40futurewei.com%7Ca271373344174f2afc5508d8c33b670c%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C0%7C637474007204890051%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=HreBlgraCVoucOQzWmZxtrvM%2FUSI%2BE7frw%2BlER0jFJY%3D&reserved=0>
 .
Since the draft is already a WG draft, want to solicit feedback from the WG if 
the changes are appropriate.

5.1    Packet Walk-Through for Scenario #1 (Homogeneous WAN)
(This is referring to a type of SDWAN network with edge nodes encrypting all 
traffic over WAN to other edge nodes, regardless of whether the underlay is 
private or public.).

A single IPsec security association (SA) protects data in one direction. Under 
the Scenario #1, two SAs must be present to secure traffic in both directions 
between any two end points, which can be two C-PE nodes, two client ports, or 
two prefixes.
Upon power up, a SDWAN node can learn client routes from the Client facing 
ports in the same way as EVPN described in RFC8388. Controller, i.e. BGP-RR, 
facilitates the IPsec SA establishment and rekey management as described in 
[SECURE-EVPN]. Controller manages how client's routes are associated with 
individual IPSec SA.
Using Figure 2 of the Section 3.2 as an example. Let's assume that the IPsec 
SAs terminate at the C-PE nodes. To enable full mesh communication within 
client CN2 that are attached to C-PE1, C-PE3, and C-PE4, six one directional 
IPsec SAs must be established: C-PE1 <-> C-PE3; C-PE1 <-> C-PE4; C-PE3 <-> 
C-PE4. The C-PE node address (or loopback address) acts as the Next Hop address 
for the prefixes attached to the C-PE node.
When a C-PE receives a packet from its client port, the C-PE uses the IPsec SA 
whose destination address matches the Next Hop address of the packet's 
destination to encrypt the packet and forward the encrypted packet to the 
target C-PE via one of the C-PE's WAN ports.
When a C-PE receives an encrypted packet from its WAN port, it decrypted the 
packet and forward the inner packet to the client port based on the inner 
packet's destination address.

Any issues with this description?

Thanks, Linda Dunbar
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