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CS 4594 Broadband Communications. SONET. Synchronous Optical Network. SONET = Synchronous Optical Network First standardized by ANSI/ECSA, now SDH by ITU-T. SONET is Time Division Multiplexing (TDM) . SONET encompasses optical and electrical specifications. SONET uses octet multiplexing.
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Synchronous Optical Network • SONET = Synchronous Optical Network • First standardized by ANSI/ECSA, now SDH by ITU-T. • SONET is Time Division Multiplexing (TDM). • SONET encompasses optical and electrical specifications. • SONET uses octet multiplexing. • SONET uses extremely precise timing. • SONET provides support for operation, maintenance, and administration (OAM).
SONET is superior to T-3 and T-4 • with improved (over T-carrier) • transport performance • ability to identify substreams • international connectivity • enhanced control and administrative functions
SONET electrical signal hierarchy • STS-1 = Synchronous transport signal level 1 • speed = 51.84 Mbit/s • designed to carry DS-3 or a combination of DS-1, DS-1C, and DS-2 signals that are equivalent to DS-3 • STS-N = Synchronous transport signal level N • speed = N x 51.84 Mbit/s • designed to carry multiple STS-1 • octet multiplexed STS-1
SONET optical signal hierarchy • OC-1 = Optical carrier level 1 (caries STS-1) • OC-N = Optical carrier level N (caries STS-N)
Sections, Lines, and Paths • Sections are bounded by repeaters or multiplexers that terminate the line. • Lines may carry several tributary signals.Lines are bounded by multiplexers. • A path goes end to end (between terminating multiplexers).
MPX MPX M1 M1 SECTION, LINE, and PATH repeater repeater section section section line path
STS-1 Frame • Each STS frame lasts 125 microseconds (8000 types a second) • STS-1 frame has 6480 bits = 810 octets • The octets are understood in terms of a table of 9 rows of 90 columns
SONET Frame 3 Columns 87 Columns Sonet Frame 9 rows
STS-1 Frame - Columns • The first three columns contain TOH = Transport Overhead: • TOH has 9 rows by 3 columns (27 octets) which is subdivided into • SOH = Section Overhead: 9 octets (3 rows of 3 columns) • LOH = Line Overhead:18 octets (6 rows of 3 columns)
MPX MPX M1 M1 SECTION, LINE, and PATH repeater repeater section section section line path
Overhead patterns - Section and Line Section Overhead Line Overhead
Overhead Streams • Section Overhead (SOH) defines and identifies frames, and monitors section errors and communication between section terminating equipment • Line Overhead (LOH) locates first octet of SPE and monitors line errors and communication between terminating equipment • Path Overhead (POH) verifies connection, and monitors path errors, receiver status, and communication between path terminating equipment
STS-1 Frame - Columns • The last 87 columns hold SPEs = Synchronous Payload Envelope • SPE has 9 rows by 87 columns which are divided into • POH = Path Overhead • payload • The SPE does not necessarily start in column 4. • The SPE does not necessarily stay within one frame.
Two SONET Frames 3 Columns 87 Columns Sonet Frame 9 rows
SPE = Synchronous Payload Envelope 3 Columns 87 Columns Sonet Frame 9 rows SPE Path overhead