Re: [spring] I-D Action: draft-previdi-spring-problem-statement-02.txt

[Yakov Rekhter <[e-mail]>]

Stefano,


> All,
> 
> this is the new version of the problem-statement draft incorporating 
> the latest comments.

Section 5.1.1.2 is clearly an improvement over what was in the
previous version, although some text is still problematic.
Specifically, "C only installs the path via AS2 in its RIB." If it
is the Adj-RIB-Out, then C wouldn't be able to advertise the path
via AS3 inside AS1 (as this path is not in the Adj-RIB-Out).  And
if it is the Loc-RIB, then the Adj-RIB-Out would have only the path
via AS2 (as the Adj-RIB-Out is populated from the Loc-RIB), and C
would not be able to advertise the path via AS3 inside AS1. Either
way, this would contradict the assumption that "C propagates all
the paths to Z within AS1 (add-path)."

You addressed one part of my comments on section 3. However,
the other part of my comments on section 3 is still not addressed.
Specifically, section 3 of draft-previdi-spring-problem-statement-02 
still contains the following:

   The source-based routing model, applied to the MPLS dataplane, offers
   the ability to tunnel services (VPN, VPLS, VPWS) from an ingress PE
   to an egress PE, with or without the expression of an explicit path
   and without requiring forwarding plane or control plane state in
   intermediate nodes.

The above claim about the ability to tunnel services is misleading,
as VPN and VPLS services may use p2mp or (in the case of VPN) mp2mp
LSPs, and providing any capability for setting up such LSPs is not
in the SPRING charter.

With this in mind I propose to replace the above with the following:

   The source-based routing model, applied to the MPLS dataplane, offers
   the ability to tunnel services (VPN, VPLS, VPWS) from an ingress PE
   to an egress PE, with or without the expression of an explicit path
   and without requiring forwarding plane or control plane state in
   intermediate nodes, but only if such tunnels are neither p2mp
   nor mp2mp tunnels.

Yakov.