The MPLS WG Archive

["Takao Okamawari" <takao_uk@hotmail.com>]

Hi all, 

I have a question about label allocation in RSVP-TE.
When a label is drawn from a label space?
On receipt of PATH or on receipt of RESV? (And reason why...)

RFC3209, 4.1.1.1 says, 
"If no label is available, the node sends a PathErr
message ..."
Since PathErr is used to notify a failure of PATH message, 
this reminds me that a label is drawn from a label space
on receipt of the PATH.

On the other hand, Yakov Rekhter says in his book 
(MPLS technology and applications) that
"When an LSR wants to send a RESV message for a new RSVP flow,
the LSR allocates a label from its pool of free labels, 
creates an entry in its LFIB with the incoming label set to 
the allocated label, and sends out the RESV message..." (pp 153)
(Does it mean PathErr is sent when RESV has failed?)

Please let me know.

Takao