McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 SONET/SDH Synchronous Optical Network/ Synchronous Digital Hierarchy SONET was developed by ANSI SDH was developed by ITU-T

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 SONET/SDH Rates STSOCRate (Mbps)STM STS-1OC STS-3OC STM-1 STS-9OC STM-3 STS-12OC STM-4 STS-18OC STM-6 STS-24OC STM-8 STS-36OC STM-12 STS-48OC STM-16 STS-96OC STM-32 STS-192OC STM-64 STS- synchronous Transport Signal STM – Synchronous Transport Modules OC- optical carriers

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure 20-1 A SONET System STS Mux/Demux – beginning & end points Regenerator – repeater that regenerates the optical signals Add/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 devices Line – portion of a network between 2 muxes Path - 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

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure 20-5 Data Encapsulation in SONET

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure 20-6 STS-1 Frame

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 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 hex C1 – Frame id B1 – LRC E1 –used for communication bet. regenerators or bet. terminals & regenerators F1 reserved for user needs D1, 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 Payload Pointers

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure STS-1 Frame Path Overhead J1 – used for tracking the path C2 – path identification byte, used to identify different protocols used at higher levels G1- sent by the receiver to communicate its status to the sender F2 – reserved for user needs H4 – multiframe indicator

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure 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 VT Types

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure STS-n Multiplexing STS Frames 3 STS-1s = 1 STS-3 4 STS-3s = 1 STS-12

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure STS Multiplexing

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure ATM in an STS-3 Envelope

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 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.