The 40 Gigabit per Second Phone Call:
Global Standards for Automatically Switched Optical Networks Enable New Market Services

Geneva, 5 December 2001 — New global standards for Automatically Switched Optical Networks (ASON) and their control mechanisms have been adopted as a result of an aggressive work programme initiated by ITU to support bandwidth-on-demand applications. The standards, which add switching capability to the installed optical fibre infrastructure, were developed and agreed upon in less than a year.

"The ASON family of standards build on Optical Transport Network (OTN) standards completed earlier this year and move us towards the Optical Internet" said Peter Wery, Chairman of ITU-T Study Group 15. "They can create tremendous business opportunities for network operators and service providers, giving them the means to deliver end-to-end, managed bandwidth services efficiently, expediently and at reduced operational cost," Wery added. ASON standards can also be implemented to add dynamic capabilities to new optical networks or established SDH networks.

The expected business benefits include:

• Increased revenue generating capabilities through fast turn-up and rapid provisioning; as well as wavelength-on-demand services to increase capacity and flexibility
• Increased return on capital from cost-effective and survivable architectures that help protect current and future network investments from forecast uncertainties
• Reduced operations cost through more accurate inventory and topology information, resource optimization and automated processes that eliminate manual steps

ASON control mechanisms provide support for both switched wavelength and sub-wavelength connection services in transport networks to provide bandwidth on-demand. Wavelength connection services make use of an entire wavelength of light while sub-wavelength services use a channel within a wavelength.

The ASON control mechanisms also enable fast optical restoration. Traditionally, transport networks have used protection rather than restoration to provide reliability for connections. With protection, connections are moved to dedicated or shared routes in the event of a failure of a fibre or network equipment. With restoration, the endpoints can "redial" to re-establish the connection through an alternative route as soon as a loss of the original connection is detected. Restoration is a defined advantage for carriers as it makes better use of the network capacity and, with this new standard, it can be performed much faster than with most proprietary restoration systems available today.

These recommendations are an important step towards the completion of the ASON series of standards. Work ahead includes the addition of detailed protocol specifications and the expansion of features for interoperable network restoration.

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ITU-T Recommendation G.807, the first standard in the Automatic Switched Transport Networks (ASTN) series approved earlier this year, addressed the network level architecture and requirements for the control plane of ASTN independent of specific transport technologies.

Agreement was reached on three new standards in the Automatic Switched Optical Networks (ASON):

• New ITU-T Recommendation G.8080/Y.1304 "Architecture for the Automatically Switched Optical Network (ASON)" specifies the architecture and requirements for the automatic switched transport network as applicable to SDH transport networks, defined in Recommendation G.803, and Optical Transport Networks, defined in Recommendation G.872. This new Recommendation is based on requirements specified in Recommendation G.807.
• New ITU-T Recommendation G.7713/Y.1704 "Distributed Call and Connection Management" gives the requirements for distributed connection management (DCM) for both the User Network Interface (UNI) and the Network Node Interface (NNI). The requirements in this Recommendation specify the signaling communications between functional components to perform automated connection operations, such as setup and release of connections. It describes DCM messages, attributes, and state transitions in a protocol neutral fashion.
• New ITU-T Recommendation G.7714/Y.1705 "Generalized Automatic Discovery Techniques" describes automatic discovery processes that support distribution connection management. Applications of automatic discovery addressed include neighbor discovery and adjacency discovery. The requirements, attributes and discovery methods are described in a protocol neutral fashion.
• An agreement was also reached on Recommendation G.7712/Y.1703 "Architecture and Specification of Data Communication Network" (see ITU press release of 30 November 2001 on Realizing the Next Generation Optical Network available here which is applicable to ASON in that it specifies the architecture and requirements for a data communication network (DCN) to support the exchange of ASON messages in addition to the traditional Telecommunications Management Network (TMN) communication. These communications take place among the transport plane, control plane, and management plane for ASON signaling and network management.

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