The term ASTN replaces the term ASON (Automatically Switched Optical Network) and is often used interchangeably with GMPLS (Generalized MPLS).
This is not completely correct as GMPLS is a family of protocols, but ASON/ASTN is an optical/transport network architecture.
Traditionally, creating traffic paths through a series of Network Elements has involved configuration of individual cross-connects on each Network Element.
ASTN allows the user to specify the start point, end point and bandwidth required, and the ASTN agent on the Network Elements will allocate the path through the network, provisioning the traffic path, setting up cross-connects, and allocating bandwidth from the paths for the user requested service.
The reservation/label distribution protocol CR-LDP has now been deprecated by the IETF in RFC 3468 [2] (February 2003) and IETF GMPLS working group decided to focus purely on RSVP-TE.