Hi Linda and Jorge,
Thanks for your comments at IETF110 meeting, and I think I need
to explain our considerations for the newly defined LSI (Logical Session
Identifier) concept.
Question 1, from Linda Dunbar, "Is the usage of LSI same as the RD for VPN
route distinguish?"
Answer: LSI(Logical Session Identifier) is mainly used for distinguishing the
different logical sessions between CE and PE device. Such session can be
established via Vxlan, IPsec, or other tunnel technologies that can span layer
3 network.
The LSI information should be transferred via the control plane and forwarding
plane. In control plane, we try to use Ethernet Tag ID/newly defined ESI type
to transfer, its purpose is to further distinguish the cusomer routes within
one provider VRF. In forwarding plane, this information should be inserted into
some place of the exising VxLAN encoding, as proposed in our
draft:https://datatracker.ietf.org/doc/html/draft-wang-bess-l3-accessible-evpn-04#section-6.1
Question 2, from Jorge Rabadan. "The ESI shouldn't be used to distinguish the
route-type 5, it is mainly used for multi-homing purpose"
Answer: Currently, we are considering using two methods to identify the routes
that associated different LSI:
Method 1: Ethernet Tag ID, which is similar with its
usage in layer 2 vlan environment.
Method 2: Newly defined ESI type(type 6)
We think both methods are approachable:
Method 1 requires also the update of
https://tools.ietf.org/html/draft-ietf-bess-evpn-prefix-advertisement-11(Ethernet
Tag ID is set to 0 for route type 5), may arises some confuse with its
original defintion.
Method 2 requires the extension of ESI type (as described in:
https://datatracker.ietf.org/doc/html/draft-wang-bess-l3-accessible-evpn-04#section-6.2).
The original purpose of ESI (mulit-homing) can also be preserved.
I hope the above explanations help.
Comments and questions are always welcome.
Best Regards,
Wei
China Telecom
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