Cabletron Systems SPECTRUM TRMMIM - Manual (Page 99)

Ring and Station Variables 5-9
Statistics
LanNet Manager IBM’s Token Ring LAN Network Manager.
Other All other protocols not described above.
Frame Sizes
Frame Sizes are only available for Ring Pie Charts and Meters. Frame Sizes
displays the number of packets counted on the ring of the following sizes:
• Up to 63 bytes
• 64 to 127
• 128 to 255
• 256 to 511
• 512 to 1023
• 1024 to 2047
• 2048 to 4095
• 4096 and up
Isolating Errors
Isolating errors report the region of a fault, therefore pointing out where on the
ring the problem is occurring. Isolating errors include line, internal, burst, A/C,
and abort errors, described below.
Line Errors
A line error occurs when there is a coding violation in the data part of the frame.
A power surge on the ring may cause the data portion of a frame or token to be
corrupted. It is the equivalent to an Ethernet CRC error in both cause (usually
electronic noise along the ring medium or other cable problems) and effect. These
errors are counted, but initiate no other recovery procedures.
Burst Error
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 typically indicates a clocking error. Usually, burst errors occur when there
was a brief electrical surge or electronic noise on the network. 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, and may cause frames to be
lost on the ring.
AC Error
AC errors indicate that the reporting station’s NAUN is faulty, because it is
unable to report its address.