Alcatel-Lucent 1665 DMX offers 5 modes of linear protection switching: unidirectional 1+1 non-revertive line switching, bidirectional 1+1 non-revertive, unidirectional 1+1 revertive line switching, bidirectional 1+1 revertive, and bidirectional optimized 1+1 protection switching. All linear protection switching occurs automatically in response to detected faults, or in response to external commands from technicians at a local or remote CIT or OS.
Beginning in Release 9.0, you can change 1+1 protection group from unidirectional to bidirectional in-service without deleting cross-connections.
Alcatel-Lucent 1665 DMX uses standard protection switching priorities as follows:
Alcatel-Lucent 1665 DMX allows you to provision these parameters with different priorities in relation to each other. For example, SF can be set with a higher priority than FS and vice versa.
Unidirectional and bidirectional 1+1 non-revertive and revertive line switching use switch procedures as specified by the SONET standards.
Alcatel-Lucent 1665 DMX offers bidirectional optimized 1+1 protection switching which uses switching procedures specified in ITU-T G.841, Annex B. Bidirectional optimized 1+1 is designed to enable interoperability between Alcatel-Lucent 1665 DMX and SDH equipment. It is a separate switching scheme from standard 1+1 bidirectional and does not work with standard 1+1.
Automatic line switches are initiated by signal fail and signal degrade conditions on the received OC-n signal. This signal's BER is calculated from violations in the SONET line overhead B2 parity byte. Signal fail is declared for incoming loss of signal, loss of frame, line AIS, or a BER exceeding a provisionable 10-3 to 10-5 threshold, while a BER exceeding a provisionable 10-5 to 10-9 threshold causes the signal degrade condition. A line protection switch is completed within 50 milliseconds of the onset of a hard failure such as a fiber cut.
In multispan applications (for example, hubbing), each OC-n span switches independently. For example, in hubbing applications, a switch on the central office-to-hub span will not cause switches on any of the hub-to-remote spans. Similarly, a line switch on a hub-to-remote span will not propagate to other hub-to-remote or central office-to-hub spans.
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