LC comment on "considerations" inter-AS section

[Eric Rosen <erosen at cisco.com>]

In  the  discussion  of inter-AS,  I  think  the  draft should  discuss  the
following issues:

- In  order to  use the  segmented inter-AS  procedures, each  ASBR  must be
  pre-configured with the  MVPNs whose trees pass through  it.  (See section
  8.2.1.1 of draft-ietf-l3vpn-2547bis-mcast.)

- One of the most important scaling properties, that of making the number of
  P-tunnels be independent  of the number of PEs in other  ASes, may be more
  theoretical than real,  at least in the shorter  term.  A segmented S-PMSI
  carries traffic from only one PE, so the number of S-PMSIs used by an MVPN
  is still limited only by the total number of PEs in the MVPN.

  To get  the desired  scaling improvement, one  must aggregate a  number of
  intra-AS segments of inter-AS tunnels  into a single intra-AS P-tunnel.  I
  don't believe there  is a specification of the method for  doing this in a
  fully  automated fashion.  Also,  this type  of aggregation  requires MPLS
  upstream-assigned labels.

These issues  seem relevant  to a discussion  of whether  segmented inter-AS
P-tunnels should be mandatory.