Post on 18-Dec-2015
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2001
SONET/SDH
Synchronous Optical Network/Synchronous Digital Hierarchy
SONET was developed by ANSISDH was developed by ITU-T
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2001
SONET/SDH RatesSTS OC Rate (Mbps) STM
STS-1 OC-1 51.840
STS-3 OC-3 155.520 STM-1
STS-9 OC-9 466.560 STM-3
STS-12 OC-12 622.080 STM-4
STS-18 OC-18 933.120 STM-6
STS-24 OC-24 1244.160 STM-8
STS-36 OC-36 1866.23 STM-12
STS-48 OC-48 2488.320 STM-16
STS-96 OC-96 4976.640 STM-32
STS-192 OC-192 9953.28 STM-64
STS- synchronous Transport Signal STM – Synchronous Transport ModulesOC- optical carriers
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2001
Figure 20-1
A SONET System
STS Mux/Demux – beginning & end pointsRegenerator – repeater that regenerates the optical signalsAdd/drop mux – add signals into a given path or remove a desired signal from a path
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2001
Figure 20-2
An Example of a SONET Network
Section – optical link connecting 2 neighbor devicesLine – portion of a network between 2 muxesPath - end to end portion of the network between 2 STS muxes
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2001
Figure 20-3
SONET Layers
Photonic Layer-Specs for optical fiber channel, sensitivity of the receiver-NRZ – 1-presence of light
Section layer -Responsible for the movement of a signal across a physical section-Framing, scrambling, error control
Line layer- STS mux and add/drop mux provide line layer functions
Path layer-Responsible for the movement of signal from its optical source to its optical destination-Transformation of signals-STS mux provides path layer functions
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2001
Figure 20-4
Device-Layer Relationship in SONET
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Figure 20-5
Data Encapsulation in SONET
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Figure 20-6
STS-1 Frame
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Figure 20-7
STS-1 Frame Overhead
SPE – Synchronous payload envelope- Contains user data and details about charges (if any)
Path overhead - end-to-end tracking information
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2001
Figure 20-8
STS-1 Frame Section Overhead
A1 & A2 – for framing & synchronization, F6 & 28 in hexC1 – Frame idB1 – LRCE1 –used for communication bet. regenerators or bet. terminals & regeneratorsF1 reserved for user needsD1, D2, D3 – for operation, administration and maintenance signaling
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2001
Figure 20-9
STS-1 Frame Line Overhead
H1, H2, H3 – identify the location of the payload in the frame
K1, K2 – used for automatic detection of problems in line-terminating equipment (mux)
Z1, Z2 – reserved for future use
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2001
Figure 20-10
Payload Pointers
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2001
Figure 20-11
STS-1 Frame Path Overhead
J1 – used for tracking the pathC2 – path identification byte, used to identify different protocols used at higher levelsG1- sent by the receiver to communicate its status to the senderF2 – reserved for user needsH4 – multiframe indicator
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Figure 20-12
Virtual Tributaries
- Partial payload that can be inserted into STS-1 and combined with other partial payloads to fill out the frames
SONET – backward compatible with the current digital hierarchy (DS-1 to DS-3
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2001
Figure 20-13
VT Types
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Figure 20-14
STS-n
Multiplexing STS Frames
3 STS-1s = 1 STS-34 STS-3s = 1 STS-12
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2001
Figure 20-15
STS Multiplexing
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Figure 20-16
ATM in an STS-3 Envelope
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Applications
• Can replace T-1 or T-3 lines
• Can be the carrier for ISDN and B-ISDN
• Can be the carrier for ATM cells
• Can support bandwidth on demand
• Can be used as the backbone or totally replace other networking protocols such as FDDI.