fleming@apple.com (10/17/89)
>10/13/89 17:04 3/171 gamiddleton@watmath.waterloo.edu (Guy Middleton) writes: >I read in the newspaper today about some Northern Telecom fibre-optic >equipment that uses a signalling technology called SONET. Does anybody know >what SONET actually is? SONET stands for Synchronous Optical Network. It is not a signalling technology (as the term would normally be understood in this newsgroup) but rather a new international standard for transmitting very-high-bit-rate signals (up to 13 gigabits per second) over single-mode fiber; Northern Telecom has also extended the system to work over digital microwave radio. Current announcements include 2.4 Gb/s products, which will be the fastest in the world when they ship next year. The major advantages of SONET are: * Multi-vendor compatibility (allowing optical mid-span meets between equipment from different vendors... e.g., Northern Telecom and AT&T. This has been an ongoing scandal for years, with an explosion in proprietary formats coinciding with divestiture and rapid advances in fiber optic technology) * Capability to extract one or more constituent signals in mid-stream (all asynchronous systems require full demultiplexing to DS1 or sometimes to analog VF, which is INCREDIBLY awkward, expensive, and prone to mistakes) * Standardized operations, administration, and maintenance. If you're not involved in the day-to-day business, it's not obvious that, with the massive growth of fiber optic capacity, the major technical challenge is no longer getting the bits into the pipe... it's making sure the right bits go in the right place and get billed to the right customer. (A massive oversimplification.) * Provision of new services to be named later. For example, some of the extensions to SONET now being negotiated relate to fiber to the home and switched multi-megabit data services for corporations. Unlike previous systems, where you would have to rip out the entire terminal electronics to provide a new service, SONET allows new services to be provisioned without disturbing the synchronous structure. Some new services will be provisionable purely via downloaded software, with no change in terminal electronics. SONET began its life at Bellcore in 1984. After a tortuous approval process, it is now accepted by the U.S., Canada, Japan, and Europe (at least... perhaps others as well). It is the first major transmission standard to be PROACTIVELY determined, rather than the old method of "well, let's see what AT&T shipped and make that a standard." As such, it bids fair to revolutionize the transmission and (to some extent) switching portions of the public network. One of the best tutorials I have seen on SONET is by Ballart and Ching in the March 1989 issue of IEEE Communications. I added a more-accessible introduction in my article published in the June 15th issue of TE&M. I'd also be happy to reply to questions of general interest via E-mail or over the net. +-----------------------------------------------------------------------+ | Stephen Fleming | Internet: fleming@cup.portal.com | | Director, Technology Marketing | Voice: (703) 847-7058 | | Northern Telecom +-------------------------------------| | Federal Networks Division | Opinions expressed are not | | Vienna, Virginia 22182 | those of Northern Telecom. | +-----------------------------------------------------------------------+