Automatic Switched Transport Network (ASTN) allows traffic paths to be set up through a switched network automatically. The term ASTN replaces the term ASON (
Automatically Switched Optical Network Automatically Switched Optical Network (ASON) is a concept for the evolution of transport networks which allows for dynamic policy-driven control of an Optical networking, optical or Synchronous Digital Hierarchy, SDH network based on signaling betw ...
) 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. The requirements of the ASON/ASTN architecture can be satisfied using GMPLS protocols developed by the
IETF or by GMPLS protocols that have been modified by the
ITU
The International Telecommunication Union is a specialized agency of the United Nations responsible for many matters related to information and communication technologies. It was established on 17 May 1865 as the International Telegraph Unio ...
. Furthermore, the GMPLS protocols are applicable to optical and non-optical (e.g., packet and frame) networks, and can be used in transport or client networks. Thus, GMPLS is a wider concept than ASTN.
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 actual path that the traffic will take through the network is not specified by the user.
Changes to the network (adding/removing nodes) will be taken into account by the ASTN agents in the network, but do not need to be considered by the user. This gives the user far more flexibility when allocating user bandwidth to provide services demanded by the customer.
GMPLS consist of several protocols, including routing protocols (
OSPF-TE
Open Shortest Path First (OSPF) is a routing protocol for Internet Protocol (IP) networks. It uses a link state routing (LSR) algorithm and falls into the group of interior gateway protocols (IGPs), operating within a single autonomous sys ...
or
ISIS-TE), link management protocols (LMP
[RFC 4204]
"Link Management Protocol"
/ref>), and a reservation/label distribution protocol ( RSVP-TE). The reservation/label distribution protocol CR-LDP
Constraint-based Routing Label Distribution Protocol (CR-LDP) is a control protocol used in some computer networks.
As of February 2003, the IETF MPLS working group deprecated CR-LDP and decided to focus purely on RSVP-TE.
It is an extension of th ...
has now been deprecated by the IETF in ''RFC 3468'' [RFC 3468]
"The Multiprotocol Label Switching (MPLS) Working Group decision on MPLS signaling protocols"
/ref> (February 2003) and IETF GMPLS working group decided to focus purely on RSVP-TE.
The GMPLS architecture is defined in ''RFC 3945''.[RFC 394]
"Generalized Multi-Protocol Label Switching (GMPLS) Architecture"
/ref>
References
Further reading
*''GMPLS: Architecture and Applications'' by Adrian Farrel and Igor Bryskin
External links
From MPLS to GMPLS
(pdf)
GMPLS Unified Control Plane
(pdf)
Evolution to All-optical Networking
(pdf)
{{DEFAULTSORT:Automatic Switched-Transport Network
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