Cabletron Systems 7C04-R User Manual

FDDI Management

4-8

Port Configuration

Estimate can range from 10

-4

 to 10

-15

, but is always displayed as the absolute 

value of the exponent; for example, if the port’s LER Estimate is computed to be 
10

-5

, the value displayed in the Port Status box will be 5, which represents an 

actual rate of 1,250 bit errors per second. The lower LER Estimate numbers 
represent the highest bit error rates.

The LEM (Link Error Monitor) Rate displays the number of times each port’s Link 
Error Monitor has detected a link error, expressed as link errors per second. A link 
error occurs when a port’s line state goes from Idle to Unknown and remains 
there for at least 80 ns, or when the line state goes from Active to Unknown and 
remains there for at least 320 ns. A growing LEM Count usually indicates a 
physical problem with the connectors or the cable between a port and the node at 
the other end of its cable segment. If you can wiggle the cable and watch the LEM 
Count increase, you know you have a faulty cable or connector. Dirt or film on the 
connector cable ends can also add to the LEM Count.

The number of times the port’s link has exceeded the configured LER Cutoff level 
and been removed as faulty (disabled by station management), expressed as 
rejects per second. SMT automatically re-enables a port when the error rate falls 
below the cutoff value.

To exit the FDDI Port Meters window, click 

. 

If you are running SPMA in conjunction with HP Network Node Manager or IBM 
NetView, the Port Configuration window will include a Graph button; select this 
button to display FDDI variables for the selected port via the graphing 
application provided by your network management platform.

If you are running SPMA in conjunction with SunNet Manager or in a stand-alone 
mode, no graphing capabilities are available, and no graph-related options will 
appear.

, for more information on the statistics described