Comments on LMP draft version 04

[Michiel van Everdingen <MvanEverdingen@lucent.com>]

Hello Jonathan,

We are very disappointed that you have not provided the
clarifications as requested in
- http://ops.ietf.org/lists/ccamp/ccamp.2002/msg00735.html
- http://ops.ietf.org/lists/ccamp/ccamp.2002/msg00651.html
nor the method of neighbor discovery as proposed in
- http://ops.ietf.org/lists/ccamp/ccamp.2002/msg00750.html

Please find below comments on the LMP draft, version 04
(http://www.ietf.org/internet-drafts/draft-ietf-ccamp-lmp-04.txt).
Hopefully clarification can be provided in a next
version.


Best regards,

Greg Bernstein (Ciena Corporation)
Michiel van Everdingen (Lucent Technologies)


General: please clarify what a control channel is. Only when that
is clarified, we can comment on the mandatory need to manage this
control channel (section 3). If a control channel can be many
things, please mention these things so we can comment on these
interpretations one by one.

Some first comments assuming an interpretation that was recently
provided on this list:

A. "control channel on top of a control network"
   http://ops.ietf.org/lists/ccamp/ccamp.2002/msg00725.html
   - From section 1: "To enable communication between nodes for
     routing, signaling, and link management, control channels must
     be established between the node pair".
     Please clarify why control channels must be established. The
     control network seems enough to enable communication.
   - From section 2: "...the control channel MUST terminate on
     the same two nodes that the TE link spans"
     What information is terminated at the end of a control channel ?
     ('electrically terminated' as mentioned in the 4th paragraph of
      section 3 does not provide much information).
     Compare e.g. LSP termination (in which an MPLS label is
     terminated/removed), TCP termination (in which the TCP header is
     terminated/removed) and STS-1 termination (in which STS-1 line
     overhead is terminated/removed). What is terminated/removed at
     the end of a control channel ?

B. "a control network is one instantiation of a control channel"
   http://ops.ietf.org/lists/ccamp/ccamp.2002/msg00835.html
   How to read sentences (taken from draft-ietf-ccamp-lmp-04.txt)
   like:
   - "Control channel management is used to establish and maintain
      control channels between adjacent nodes."
   - "LMP requires that a pair of nodes have at least one active bi-
      directional control channel between them."
   - "the control channel MUST terminate on the same two nodes that
      the TE link spans"
   when a control network is used to instantiate the "control
   channel" (i.e. try to replace "control channel" with "control
   network" in the indicated sentences) ?


LMP version 4 now includes some neighbor discovery (3rd paragraph
section 3 and start of section 5). A separate draft is provided
to specify discovery in the case of "out-of-band control channels"
  http://www.ietf.org/internet-drafts/draft-lang-ccamp-lmp-bootstrap-00.txt
Why separating the "in-band" and the "out-of-band" cases in different
drafts, especially if a method exists that does not make any assumption
on the configuration of the control network ?
  http://www.ietf.org/internet-drafts/draft-everdingen-ccamp-lmp-update-00

Section 1, 4th paragraph: "a data-bearing link may be either a
'port' or a 'component link' depending on its multiplexing capability".
The multiplexing capabilities are present at the *end-points* of the
data-bearing link. The data-bearing link itself does not have
multiplexing capabilities. See
  http://www.ietf.org/internet-drafts/draft-everdingen-ccamp-lmp-update-00
on how to use alternative terminology (TTP & CTP).

Section 1, 4th paragraph: the "timeslot label" that is needed to
identify a "link resource" is not mentioned anymore in the remainder
of the document.

Section 3.2: what IGP is meant here ? The IGP building the topology
of the "control plane" or the "signaling plane" ? See for definitions
of these terms:
  http://ops.ietf.org/lists/ccamp/ccamp.2002/msg00725.html

Section 14.8: In case the test message is transmitted over the DCC
"with bit-oriented HDLC framing format", is this by-passing the
DCN ? Please spend more words on how to prevent conflicts (e.g.
using a proprietary PPP protocol id to prevent the test message
to be handled by the normal routing mechanisms of DCN ?)