Page 328 - Optical Communications Essentials

Network Management

318 Chapter Eighteen

Optical amplifier
1510-nm or OADM 1510-nm
optical optical
coupler coupler

λ OSC , λ 1 ,... λ N λ 1 , λ 2 , ... λ N λ 1 , λ 2 , ... λ N λ OSC , λ 1 ,... λ N
λ OSC λ OSC
Monitoring &
Monitoring &
1510-nm control 1510-nm
1510-nm
1510-nm
control
receiver processing transmitter
receiver
transmitter
processing
Figure 18.9. The OSC bypasses the device being monitored.
using a 33rd wavelength (or channel 0), which allows the OSC to control and
manage traffic without deploying a separate Ethernet control connection to
each active device in the network.
As shown in Fig. 18.9, the OSC bypasses the device being monitored and
always terminates on a neighboring node. This is in contrast to data channels
which do not necessarily terminate on a given node (such as an optical ampli-
fier or an OADM).
An OSC carries out the following types of functions:

■ Discovery. This function sends packets over the OSC to discover the logical
topology of the network
■ Monitoring. With this keep-alive function, nodes exchange packets that allow
them to determine the operational status of their neighbors.
■ Management. IP packets are carried over the OSC to support SNMP and
Telnet sessions

A variety of vendors offer 1510-nm channel couplers and lasers that operate
from the 2- to 155-Mbps data rates used on the OSC.

18.7. Summary
System maintenance and system control are necessary and important functions
in any network. To meet the requirements of the service-level agreements with
their customers, service providers must manage and monitor the key perform-
ance parameters of the network very closely. The performance and operations
management of a network requires the ability to configure and monitor net-
work devices quickly and easily so that connections and services are always
available. Early detection of changes in network status is critical in avoiding
potential problems. This requires the use of sophisticated instruments and soft-
ware-based diagnostic tools.
Once the hardware and software elements of an optical network have been
installed properly and integrated successfully, they need to be managed to

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