Hi, recently I encountered a port disabled by err-disable due to collision. Anyone know what is the threshold of the collisions (excessive or late collision) that may result in err-disable. How cisco switches know when to disable the port when it detected the collision on a port?
16 collisions in a row implies an "excessive collision"
By definition, the single collision counter increments when frames have been successfully transmitted after one collision. Multiple collisions occur when more than one collision occurs before a frame is transmitted.
So, when a single or multiple collision occurs, a frame is eventually transmitted, so the threshold counter is effectively zeroed out again.
An excessive collision, by definition, occurs if an interface fails to allocate a slot in which it can transmit its frame without another collision 16 times. This is when the interface is errdisabled.
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