Cabletron Systems SPECTRUM TRMMIM - Manual (Page 87)

Setting and Viewing Station Alarms 4-7
Alarm Configuration
The Alarm Type options at the top of the window represent the variables for
which you can assign station-level alarm thresholds. To change the status or
threshold for an alarm type, you must first click on its option at the top of the
window; threshold and status changes will be applied to the alarm type selected
at the time the changes are made and to the stations as determined by the current
setting in the Set Alarm For field. You can set an alarm threshold for the following
variables:
Line Errors A line error indicates the presence of a coding violation
between the starting and ending delimiters of data, a
frame check sequence error, or a code violation in a
token. These can be caused by power surges on the ring;
they are counted, but initiate no other recovery
procedures.
Internal Errors An internal error is counted when a station recognizes a
recoverable internal error in its own adapter (and may
temporarily remove itself from the ring). A large number
of internal errors indicates a station in marginal
operating condition; possible problems include
inoperable chipset, timers, or counters.
Burst Errors A burst error occurs when five half-bits of Manchester-
encoded data are received by a station without a phase
change (a signal transition from 0 to 1 or from 1 to 0).
This error is normal when stations enter or leave the ring
without phantom current; however, it can also indicate a
problem with the receiver on the reporting node, the
transmitter on its NAUN, or the cabling or hub hardware
between them. Burst errors will cause the active monitor
to initiate the ring purge process.
NOTE
Alarm conditions which occur over the span of two timebase intervals will not be detected,
even if the threshold is crossed within a period of time that is less than or equal to the
defined timebase interval. For example, if you set your timebase to 10 seconds and an
alarm threshold to 50, an alarm will be generated if 50 of the specified events are detected
within a specific 10-second interval defined by the device. If, however, those 50 events
occur in any 10-second time frame which straddles two device-defined intervals — say, 25
in the last five seconds of one interval, and 25 in the first five seconds of the following
interval — that condition will not be detected, and no alarm will be generated. These
conditions are most likely to occur when a large threshold is used with a short timebase
interval.