Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!rutgers!texbell!vector!telecom-gateway From: optilink!elliott@ames.arc.nasa.gov (Paul Elliott x225) Newsgroups: comp.dcom.telecom Subject: Re: What is SONET? Message-ID: Date: 16 Oct 89 16:55:12 GMT Sender: news@vector.Dallas.TX.US Organization: Optilink Corporation, Petaluma, CA Lines: 46 Approved: telecom-request@vector.dallas.tx.us X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@vector.dallas.tx.us X-TELECOM-Digest: volume 9, issue 455, message 6 of 11 In article , 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 is an acronym for Synchronous Optical NETwork. It is not really a signaling technology, but rather is the North American fiber optic transmission standard. The SONET standard is described in Bellcore TA-TSY-000253 (Issue 3, July 1988). SONET transports telephony signals as payloads of multiple DS0 (Dee-Ess-Zero) channels, each DS0 being 64 Kbit/s arranged as 8 bits/channel with an 8000 Hz channel repetition rate. 24 channels are grouped (with one frame bit) into a frame; the resulting signal is called a DS1, and is the basic T1 signal. I won't go into the various signaling and framing formats here (unless someone really twists my arm). SONET provides for several optical transmission rates; these are: STS-1, OC-1: 51.840 Mbit/s, 672 DS0 channels STS-3, OC-3: 155.52 Mbit/s, 3x OC-1 ... and on, up to: STS-48, OC-48: 2488.32 Mbit/s, 48x OC-1 (STS-N = Synchronous Transport Signal level N, the signal description) (OC-N = Optical Carrier level N, the STS-N after conversion to light) Note that the data rates above do not correspond exactly to the number of DS-0 channels being transported. This is due to additional overhead data in the SONET signal. The SONET signal uses laser light sources and single-mode fiber. Here at Optilink, we were amused to see the Northern Telecom press release (in which they claimed to be the first), as we have had a SONET digital loop carrier system in field-trials at several sites for a few months now. The article in the paper was a bit sketchy, so perhaps they are indeed first at _something_SONET_, but certainly they are not alone in the field. Paul M. Elliott Optilink Corporation (707) 795-9444 {pyramid,pixar,tekbspa}!optilink!elliott "I used to think I was indecisive, but now I'm not so sure."