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Chapter 6Client Layers of the Optical Layer

A. In the backbone networks a. Synchronous Optical Network (SONET)/ Synchronous Digital Hierachy (SDH) b. Internet Protocol (IP) c. Asyuchronous Transfer Mode (ATM)B. In the metro networks a. Gigabit Ethernet b. Fiber channel

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6.1 SONET/SDH

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6.1.1 Multiplexing

A. The synchronous transport signal level-1 (STS-1) has the basic signal rate 51.84 Mb/s

B. The digital signal-0 has the rate 64 Kb/s

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6.1.1 Multiplexing

STM-1 (synchronous transport module-1) has the rate 155.52 Mb/s which is the same as STS-3

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6.1.2 SONET/SDH Layers

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The path layer is responsible for end-to-end connections.

The line layer is terminated at each intermediate line terminal (TM) or add/drop multiplexer (ADM). The line layer multiplexes a number of path layer connections onto a single link between two modes.

The physical layer is responsible for actual transmission of bits across the fiber.

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6.1.3 SONET Frame Structure

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Section Overhead

a. Framing (A1/A2):for delineating the frame.

b. Section Trace (J0)/Section Growth (Z0): J0 is present in the first STS-1 in STS-N is used to carry an identifier.Z0 is present in the remaining STS-1s and its use is to be determined.

c. Section BIP-8 (B1):This byte is located in the first STS-1 and is used to monitor the BER of each section (a bit interleaved parity)

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d. Orderwire (E1):for maintenance (voice channel).

e. Section User Channel (F1):for inserting additional user-specific information.

f. Section Data Communication Channel (D1,D2,D3):for maintenance purposes such as alarms, and control.

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Line BIP-8 (B2): To carry a bit interleaved parity check value of each STS-1 within the STS-N.

APS channel (K1,K2): To provide a channel for carrying signaling information during automatic protection switching (APS).

Line Data Communication Channel (D4~D12): To carry a line data communication channel for maintenance purposes such as alarms, monitoring, and control.

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Path OverheadSTS Path trace(J1):To carry a path identifier.STS Path BIP-8(B3):To carry a bit interleaved

parity check value for the previous STS SPE.

STS Path Signal label(C2):To indicate the content of the STS SPE (each type of signal mapped into a SONET STS-1).

Path Status(G1):To convey the performance (error count) from the destination to the source.

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6.1.4 SONET/SDH Physical LayerApplication categories a. Interoffice connection (I) ≤ 2km b. Short haul (S) ≤ 15km at 1310nm ≤ 40km at 1550nm c. Long haul (L) ≤ 40km at 1310nm ≤ 80km at 1550nm d. Very long haul (V) ≤ 60km at 1310nm ≤ 120km at 1550nm e. Ultra long haul (U) ≤ 160km at 1550nm

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6.1.5 Elements of a SONET/SDH Infrastructurea. Terminal Multiplexer (TM)b. Add/drop Multiplexer (ADM)c. Digital Crossconnect (DCS)

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6.3 Internet Protocol (IP)

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6.4 Storage-Area Networks (SANS)a. Enterprise serial connection (ESCON)

b. High performance parallel interface (HIPPI)

c. Fiber Channel