528
13 Fiber Optic Communication Networks
Fig. 13.13 Generic configuration of a large SONET or SDH network consisting of linear chains
and various types of interconnected rings
Fig. 13.14 Functional concept of an electronic add/drop multiplexer for SONET/SDH applications
OC-12 is passed through and the two OC-3s are dropped by the first ADM. Then,
two more OC-12s and one OC-3 are multiplexed together with the OC-12 channel
that is passing through and the aggregate (partially filled) OC-48 is sent to another
ADM node downstream.
The SONET/SDH architectures can also be implemented with multiple wavelengths. For example, Fig. 13.15 shows a dense WDM deployment on an OC-192
trunk ring for n wavelengths (e.g., one could have n = 16). The different wavelength
outputs from each OC-192 transmitter are passed first through a variable attenuator to equalize the output powers. These are then fed into a wavelength multiplexer,
possibly amplified by a post-transmitter optical amplifier, and sent out over the transmission fiber. Additional optical amplifiers might be located at intermediate points
and/or at the receiving end.
13 Fiber Optic Communication Networks
Fig. 13.13 Generic configuration of a large SONET or SDH network consisting of linear chains
and various types of interconnected rings
Fig. 13.14 Functional concept of an electronic add/drop multiplexer for SONET/SDH applications
OC-12 is passed through and the two OC-3s are dropped by the first ADM. Then,
two more OC-12s and one OC-3 are multiplexed together with the OC-12 channel
that is passing through and the aggregate (partially filled) OC-48 is sent to another
ADM node downstream.
The SONET/SDH architectures can also be implemented with multiple wavelengths. For example, Fig. 13.15 shows a dense WDM deployment on an OC-192
trunk ring for n wavelengths (e.g., one could have n = 16). The different wavelength
outputs from each OC-192 transmitter are passed first through a variable attenuator to equalize the output powers. These are then fed into a wavelength multiplexer,
possibly amplified by a post-transmitter optical amplifier, and sent out over the transmission fiber. Additional optical amplifiers might be located at intermediate points
and/or at the receiving end.