Chapter 6
Client 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 Overhead
STS 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 Layer
Application 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 Infrastructure
a. 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
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