3com SuperStack 3 NBX Manual De Usuario

C

HAPTER

 10: T

ROUBLESHOOTING

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Carrier Fail Alarm (Red CFA) — A state that exists at a downstream 
terminal device, based upon the terminal device detecting an 
incoming LOS or LOF.

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AIS, Keep-alive/Blue — A signal that is transmitted instead of the 
normal signal to maintain transmission continuity and to indicate to 
the receiving equipment that there is a transmission interruption either 
at the equipment that is generating the AIS signal or upstream of that 
equipment. The all ones signal is generated:

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To maintain transmission continuity

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To notify downstream equipment of a transmission fault

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To indicate to downstream equipment that a DS1 framed signal is 
not being generated

The transmission fault may be located at the equipment that is 
generating the alarm signal, or it may be located upstream of that 
equipment.

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AIS CFA (also known as Blue CFA) — A state that exists at the 
downstream equipment and indicates that it has detected an AIS 
signal from the upstream equipment.

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RAI (also known as Yellow Alarm Signal) — A signal transmitted in 
the outgoing direction when a terminal determines that it has lost the 
incoming signal. The terminal equipment generates the Yellow Alarm 
Signal for a minimum of 1 second using one of these methods:

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If you are using Super Frame (SF), the terminal equipment 
generates the Yellow Alarm Signal by setting the second bit in all 
channels of the Super Frame to 0 (zero).

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If you are using Extended Super Frame (ESF), the terminal 
equipment generates the Yellow Alarm Signal by sending an 
alternating pattern of 8 ones followed by 8 zeros on the Facilities 
Data Link (FDL).

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Yellow CFA — A state that is activated at the terminal equipment 
when the terminal equipment detects a Yellow Alarm Signal. The 
Yellow Alarm Signal comes from the equipment at the other end