spc connections

["Adrian Farrel" <adrian@olddog.co.uk>]

Lyndon,

Thank you for raising this. There is certainly a lack of clarity in 3473 in this regard,
which is perhaps unfortunate.

In the earlier versions of the GMPLS work, this was made very explicit (sic) because
egress label control was invented before it was generalized to explicit label.

There is some reference to this in RFC3471 (of course, the function was originally
independent of signaling protocol), but no explicit procedures.

This descriptive deficiency has been addressed in draft-ccamp-gmpls-overlay. There is no
change in protocol to enable this function, merely a description of how it all works.

Hope this helps.

Cheers,
Adrian
=====================


Hi Adrian,

A couple of times now it's been suggested that Explicit Label Control is a way to
do SPC connections instead of the SPC_Label sub-object.  I'm wondering if
people have a different model of SPC connections in mind.  The procedures in
RFC 3473 for Explicit Label Control are as follows:

   [when a label sub-object is present]  If the U-bit of the
   subobject being examined is clear (0), then value of the label is
   copied into a new Label_Set object.  This Label_Set object MUST be
   included on the corresponding outgoing Path message.

   If the U-bit of the subobject being examined is set (1), then value
   of the label is label to be used for upstream traffic associated with
   the bidirectional LSP.

Neither of these would seem to help you for SPC, since there is no outgoing PATH
message at the network endpoint, the endpoint call control is handled by
the management system and not using a UNI or overlay interface (at least
as defined in G.8080).

Explicit Label Control seems like it would help you control the label assignment
within the signaled portion of a connection.


Cheers,

Lyndon