Re: Moving LSP ownership between control plane and management plane

[George Newsome <gnewsome@ieee.org>]

Adrian,

You asked for comments on this proposal, which was presented to ITU-T 
Q14 experts in January of this year.

There are so many issues involved in moving a connection from the 
management plane to the control plane that involve intensive management 
action, that it is not evident that signaling need be involved at all.

As a personal opinion, it makes little sense to consider moving the 
connection. It makes more sense to replace the connection with one set 
up via the control plane, and to then delete the original management set 
up connection.

Appended is an excerpt of the meeting report detailing some of the 
issues that need to be resolved before signaling need be considered.

Regards

	George

Excerpt of the meeting report of Q14 Experts, January 2005

WD06 (Marconi) "G.7713 Modification in order to support Circuit 
Migration" contains a modified version of draft G.7713 Revision as was 
presented in the Berlin meeting (WD 11, i.e., TD50/3 Dec.2004).  This 
contribution addresses SP24 (PC ? SPC) of G.7713. It proposes to extend 
the concept of Call/Connection setup to setup/adopt and release to 
release/de-adopt. In Connection Adoption both the SNC are not actually 
created and the LC are not actually established due to the fact that the 
underlying physical resources are already in place. In the 
Call/Connection dis-adoption SNC-LC-SNC is not actually de-allocated, 
only the Control Plane information associated with then is removed and 
the ownership is moved to Management Plane. Attributes for indicating 
Adoption/Dis-adoption are proposed for the INNI Connection messages.

The discussion was mainly on the Management plane and Control plane 
actions required before signalling is involved. The group noted that the 
following issues need to be addressed:

- Naming of transport resources to the control plane.  Before a call can 
be placed under signalling control, links that are involved in the 
connection need to be given control plane names.  Without these, no 
explicit route can be formed to match the resources of the connection.

- Resource state while under dual CP and MP views.  After resources are 
given control plane names, the resources are still viewed by the 
management plane.  It may be necessary to create a new state for the 
resource to indicate that the management plane cannot perform some 
actions on the connection points as the control plane is about to take over.

- Role of discovery functions (esp. CELA).  After control plane names 
are allocated, distributed control plane functions need to be associated 
and communication adjacencies formed.  This too is a precursor to any 
signalling procedures in migrating from the MP to CP.

- Similarity of migration to synchronization after CP failure and 
subsequent recovery.  Connection control procedures might be the same in 
migrating a call from the MP to the CP as the situation when the CP has 
failed and is recovering.  Here, the network connections are already in 
place, but connection and call state need to be created to match it. 
Knowledge of the call and what the connection should be is obtained from 
the MP for migration, and from some reliable database in the recovery case.

- Call awareness of migration vs. connection being unaware of migration. 
 When connection state is being created to match an existing 
connection, the connection controllers (CCs) do not require awareness of 
why this is happening as the context could be migration or recovery.  A 
mechanism to create control state without affecting transport plane 
state is needed in the CCs.  Call controllers though do need migration 
awareness as they need to obtain/derive call identification from the MP.

In summary, the group decided that it is premature to consider 
signalling procedure before the above issues, amongst other, have been 
studied. However the contribution does enable the group to expose in a 
larger context the interaction between CP and MP for connection 
migration. The above issues were included in SP24 of the G.7713 Living 
List (see WD22).