Hi Robert,
Here is the text from RFC4364 regarding to option B.
In this procedure, the PE routers use IBGP to redistribute
labeled VPN-IPv4 routes either to an Autonomous System Border
Router (ASBR), or to a route reflector of which an ASBR is a
client. The ASBR then uses EBGP to redistribute those labeled
VPN-IPv4 routes to an ASBR in another AS, which in turn
distributes them to the PE routers in that AS, or perhaps to
another ASBR which in turn distributes them, and so on.
This procedure requires that there be a label switched path
leading from a packet's ingress PE to its egress PE. Hence the
appropriate trust relationships must exist between and among
the set of ASes along the path. Also, there must be agreement
among the set of SPs as to which border routers need to receive
routes with which Route Targets.
-end
Option C request set up two LSP tunnel, one from ingress PE to egress PE,
second from ingress PE to ASBR to solve the issue in IGP.
Lucy
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On Behalf Of Robert
> Raszuk
> Sent: Wednesday, October 31, 2012 11:55 AM
> To: Lucy yong
> Cc: Luyuan Fang (lufang); [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]
> Subject: Re: comment on draft-fang-l3vpn-virtual-pe-framework-01
>
> Lucy.
>
> > To use MPLS LSP tunnel, option B requires pre-build MPLS
> > LSP tunnel between two PEs that belong to different ASes, which
> requires two
> > SPs pre-provisioning process that may not apply to here.
>
> Incorrect.
>
> Option B does not require "pre-build MPLS LSP tunnel between two PEs
> that belong to different ASes" - that would be option C.
>
> In fact option B does not require any pre established LSP or IP tunnel
> between PE-PE. Option B ASBR set's next hop self on VPNv4/v6 routes
> hence it terminates any corresponding transport encapsulation used in
> it's own domain.
>
> Cheers,
> R.
