Limitations and Troubleshooting
The main limitation of CSMA/CD is collisions. Collisions occur more frequently as the utilization of the Ethernet segment increases. At very high levels of utilization, collisions become so bad as to affect the higher-level protocols. This will show up as applications timing out or as significant performance degradation. Attaching key servers and routers via a full-duplex connection to the network can alleviate this.
The most common problems tend to involve a mismatch of speed, duplex, or encapsulation type. An auto option on the speed and duplex commands allows the router to auto-sense the speed or duplex. It is best to check that both devices are negotiated to the appropriate speed and duplex. Some stations receive multiple encapsulation formats but only respond with a specific encapsulation. When using anything other than the default encapsulation type, be sure that all stations on the segment support the encapsulation that you are using.