itu charters optical recommendations

itu charters optical recommendations

By PAUL A. BONENFANT

Anticipating that the fully optical network will soon become reality, the International Telecommunication Union`s (itu`s) Telecommunication Standardization Sector Study Group 15 has created a new Question (Q.20/15) on optical networking. At the itu meeting last April, the experts for this new question, chaired by Pietro DiVita of cselt (Italy), chartered a series of new recommendations aimed at addressing all aspects of optical networking. A work plan was developed, allocating new optical networking recommendations to the pertinent itu questions. Each of the proposed new optical networking recommendations is briefly described below.

A recommendation provisionally called G.ons (structures and mappings for the optical network) was chartered to capture "structure and mapping" aspects of optical networking. This includes the definition of optical layer overheads that will be used to support integrity supervision of the transport of optical wavelength signals and the definition of auxiliary overhead(s) to support a "data-communications channel" function, for example.

Recommendations G.oeg (types and general characteristics of optical network elements) and G.oef (functional characteristics of optical network elements) were chartered to describe functional aspects of optical network elements.

Recommendation G.oni (information models for optical network elements) was chartered to capture management information models for optical network elements that will be developed as the work on G.oeg and G.oef progresses. To capture management aspects of optical networking equipment, it was proposed to develop a new Recommendation G.onm (management of optical network elements).

To capture transmission aspects related to components and subsystems for optical networking equipment (such as optical add/drop multiplexers and optical crossconnects), it was proposed that a recommendation, provisionally called G.onc (optical network components and subsystems), be developed.

In addition, physical layer aspects of optical networking systems need to be addressed. Recommendation G.692 (formerly G.mcs) (see Lightwave, August 1997, page 22) addresses point-to-point wavelength-division multiplexing (wdm) line systems optimized for long-haul transport. Interoffice optical networks, and in particular, networks designed for metropolitan use, will provide a different set of design guidelines. These new physical layer aspects will be captured in a new Recommendation G.onp (physical layer aspects of optical networks).

Finally, a "framework" recommendation, G.onf (framework for optical networking recommendations), will be developed, addressing the recommendations (either already prepared or under development in the various questions) on every relevant aspect of optical networks, indicating the links among them and the rationale followed in their preparation.

Each of the proposed new optical networking recommendations will be developed using a phased approach. Phase 1 will emphasize point-to-point wdm line systems; Phase 2, extension to optical add/drop multiplexing and crossconnection; and Phase 3, further extension to optical layer survivability. While ambitious, a series of recommendations addressing Phase 1 is expected to be completed by year-end 1998, with the next series of recommendations addressing Phase 2 (and possibly aspects of Phase 3) expected to be completed by 2000. q

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