The longer a given network segment is, the more time it takes for a signal to travel over it. The intent of the configuration guidelines is to make sure that the round trip timing limits are met, no matter what combination of media segments are used in the system. The configuration guidelines provide rules for combining segments with repeaters so that the correct signal timing is maintained for the entire LAN. If the specifications for individual media segment lengths and the configuration rules for combining segments are not followed, then computers may not hear one another's signals within the required time limit, and could end up interfering with one another.

The correct operation of an Ethernet LAN depends upon media segments that are built according to the rules published for each media type. More complex LANs built with multiple media types must be designed according to the multi-segment configuration guidelines provided in the Ethernet standard. These rules include limits on the total number of segments and repeaters that may be in a given system, to ensure that the correct round trip timing is maintained.