5-6
T
ROUBLESHOOTING
Intermittent Errors
on an Operating Ring
An operating ring may experience occasional soft errors. This
occurrence is normal in Token Ring devices. Usually, these errors are
caused by stations removing themselves from and inserting themselves
on the ring. A low soft-error level does not affect network
performance.
The following error types are reported by stations:
■
Line
■
Burst
■
Lost token or frame
Rings that exhibit continual soft errors, particularly in the absence of
insertion and removal activity, may be suffering from:
■
Excessive noise or jitter
■
Facility wiring
■
Devices that do not meet specifications
Ring Failures
In some situations, an operating ring may fail. However, the ring wraps
to the backup path and continues operation. If a module fails, it
removes itself off of the backplane and the remainder of the ring
continues to operate.
This may be reported by stations as “Ring Beaconing”, or stations may
simply fail to attach to the ring. Module beacon recovery isolates
virtually all faults in the data path.
Ring failure usually indicates:
■
Problems in the trunk cabling
■
Ring speed has been incorrectly set for the module
To resolve a ring failure:
1
Verify that all Ring-In/Ring-Out cables are connected. A broken
Ring-In/Ring-Out copper cable can cause the ring to fail, particularly
when attached to other vendors’ equipment.
2
Verify that any other devices in the trunk path (for example, repeaters)
are operating properly.
