Cabletron Systems 24 Benutzerhandbuch

 

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wrong ring speed. If a ring speed mismatch is detected, the STH disables 
the port to keep the misconfigured station isolated from the ring and 
provides a simple visible LED signal (blinking red at the port’s LED) to 
indicate to the user that Speed Fault Protection has disabled the port. The 
port remains disabled until the ring speed mismatch condition is 
removed or resolved. 

 

On each TCU port, STH hubs provide active circuitry which filters, 
equalizes, and amplifies all received signals before transmitting them to 
the next point on the ring. The result is enhanced signal integrity and 
extended maximum station lobe cable distances.

 

Both the STH-22 and the STH-42 can be upgraded to 24 ports using the 
following daughter board upgrade kits:

 

•

TR-UTP-UGKT for STH-22.

•

TR-STP-UGKT for STH-42.

 

To guard against interruptions in network operations due to beaconing 
conditions, the STH supports Cabletron Systems’ advanced Automatic 
Beacon Recovery Process which automatically partitions problematic 
lobes from the ring, allowing the rest of the ring to continue operating. 
(ABRP engages even before the IEEE standard beacon recovery process 
begins and is able to treat conditions beyond the scope of the IEEE 
process.) It is the stack’s intelligent hub that actually executes the ABRP 
algorithm. The intelligent hub also checks partitioned lobes periodically 
and re-enables them automatically once they have recovered.

 

Whereas a station signals a TCU to open its interface by sending a 
phantom current down its lobe cable, a passive Multi-Station Access Unit 
can not provide phantom current. A TCU Ring Out port is therefore 
configured to ignore the absence of phantom current in the connecting 
cable and to look instead for the presence of data bits to determine link 
status.