Subject: [mpls] draft-fbb-mpls-gach-adv and LMP

From: Stewart Bryant <[email-masked]>
Date: Mon, 14 Nov 2011 02:50:25 +0000

I was asked just now about the use of LMP instead of defining
a new protocol.

I just took a quick look at RFC4204 in the introduction it
says:

The two core procedures of LMP are control channel management and
link property correlation.  Control channel management is used to
establish and maintain control channels between adjacent nodes.  This
is done using a Config message exchange and a fast keep-alive
mechanism between the nodes.

SB>  We do not need this fast keep alive - BFD provides the fast
SB>  KA in MPLS-TP.

The latter is required if lower-level
mechanisms are not available to detect control channel failures.
Link property correlation is used to synchronize the TE link
properties and verify the TE link configuration.

LMP requires that a pair of nodes have at least one active bi-
directional control channel between them.

SB>  We may not have this.

Each direction of the
control channel is identified by a Control Channel Id (CC_Id), and
the two directions are coupled together using the LMP Config message
exchange.  Except for Test messages, which may be limited by the
transport mechanism for in-band messaging, all LMP packets are run
over UDP with an LMP port number.

SB>  We may not have UDP/IP available in MPLS-TP

SB>  A number of the authors of LMP were in the room, so if
SB>  they think that we should consider elements of LMP for this
SB>  purpose, then perhaps we can talk whilst we are at IETF.

- Stewart