sonet 101

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HDSL What • IXC • BISDN • is CCITT • SONET?
DID • NANP • LATA • MFJ • OSI • UNI • VSAT • WATS • ADSL • FTTC • GSM • HDSL • RHC • SONET • TCP/IP •
NEW STANDARD FOR FIBER-OPTIC TRANSPORT
SONET (Synchronous Optical Network) is a standard for optical transport formulated
by the Exchange Carriers Standards Association (ECSA) for the American
National Standards Institute (ANSI), which sets industry standards in the U.S. for
telecommunications and other industries.
The standard has also been incorporated into the Synchronous Digital Hierarchy
recommendations of the Consultative Committee on International Telegraph and
Telephone (CCITT) (now called the International Telecommunications Union
[ITU]), which sets standards for international telecommunications.
The standard was initiated by Bellcore on behalf of the Regional Bell Operating
Companies (RBOCs) and others for the following key purposes:
• Compatibility of equipment by all vendors who manufacture to the standard
often referred to as “mid-span meet”
• Synchronous networking
• Enhanced OAM&P (operations, administration, maintenance, and provisioning)
• More efficient add/drop multiplexing (ADM)
• Standards-based survivable rings
• The recent positioning of the network for transport of new services, such as
Asynchronous Transfer Mode (ATM)
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In brief, SONET defines optical carrier (OC) levels and electrically equivalent
synchronous transport signals (STSs) for the fiber-optic based transmission
hierarchy. The standard SONET line rates and STS-equivalent formats are shown
in Figure 1-1. The fiber-optic rates shown in bold seem to be the most widely
supported by both network providers and vendors.
SONET 101