Optical Networks - _9_6 Interworking between Layers_111

Optical Networks - _9_6 Interworking between Layers_111 -...

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Unformatted text preview: 564 Network Survivability protection mechanisms. The former has precomputed protection paths, and the latter computes protection paths after the failure is detected. For span and path protection switching, RSVP can be used to carry APS mes- sages. For span protection, APS messages can also be carried by the GMPLSs Link Management Protocol or by the data plane such as SONET/SDH APS signaling. 9.6 Interworking between Layers We have seen that protection functions can be done in the optical layer, SONET/SDH layers, or in the service layer (IP/MPLS). How should protection in the network be coordinated between all these layers? By default, the protection mechanisms in different layers will work independently. In fact, a single failure might trigger multiple protection mechanisms, all trying to restore service simultaneously, which would result in a large number of unneces- sary alarms ooding the management center. This results in allocating protection bandwidth at each of the layers, which is inefficient.bandwidth at each of the layers, which is inefficient....
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