Isolating Error Counters

Line Error

The line error counter is contained in all adapter configurations. It is incremented no more than once per frame whenever (a) a frame is repeated or copied, or (b) the error detect indicator (EDI) is zero in the incoming frame, or (c) one of the following conditions exists:

1.

A code violation exists between the starting delimiter (SD) and the ending delimiter (ED) of the frame.

2.

A code violation exists in a token.

3.

A frame check sequence (FCS) error exists.

Burst Error

The burst error counter is contained in all adapter configurations and is incremented when the adapter detects the absence of transitions for five half-bit times between SD and ED.

Only one adapter detects the burst five condition because the adapter that detects a burst four condition (four half-bit times without transitions) conditions its trasmitter to transmit idles if the burst-five condition is detected.

ARI/FCI (A/F Bit, A/C Bit) Set Error

ARI = address recognized indicator

FCI = frame copied indicator

The ARI/FCI set error counter is incremented when an adapter receives more than one AMP or SMP MAC frame with ARI/FCI equal to zero, without first receiving an intervening AMP MAC frame.

The counter indicates that the upstream adapter is unable to set its ARI/FCI bits in a frame that it has copied.