The MPLS WG Archive

["Vishal Sharma" <v.sharma@ieee.org>]

Hi Anna,

As a continuation of my previous email, here are a few more comments
on the draft. Some are editorial, some technical.

-Vishal

i) The draft mentions at various points "See Section 11". I think
what is meant is probably Section 10.

ii) References [lakshman] pp. 7 and [MPLS_DIFF] pp. 23 seem to
be missing.

iii) The definition of MP on pp. 4 says "in case of one-to-one
backup, this is where multiple detours converge." Not sure why
this has to be?

iv) In Section 6.2, when discussing the distributed computation
model, the last line on pp. 13 states "But again IGP-TE extensions
is a benefit, not a requirement for this solution to work." If IGP-TE
extensions are not used, is the assumption that the backup bandwidth
pool for all links is explicitly configured at every node?
(since an explicitly defined backup bandwidth pool is one of the
key pieces of this [distributed] model).

v) Section 7, pp. 17, para 3, mentions that "the first case [a downstream
router fails but a link does not] is typically identifiable by means of
RSVP Hellos or some fast IGP Hellos mechanism". How so? If I don't receive
Hellos, I know I cannot reach my neighbor, but cannot say anything about
whether
my neighbor or our intervening link is down. Yes?

vi) Section 12 states that the PCS being stateless is the preferred
approach.
How so?
It seems that for the centralized computation model (with zero b/w
reservations
for backup LSPs) to work, the PCS must keep state on which primary and
backup
LSPs are placed where, on how much b/w each uses, and on the residual
bandwidth
of each network link.