Q: Do you know of a good reference for determining cabling distances using Category 5 cable for Token Ring? I need to determine the lengths possible when multiple closets are involved. Also, what is the best way to handle shielded and unshielded twisted-pair (stp/utp) lobes on the same Token Ring local area network (LAN)?
Kevin Scully
Automatic Data Processing bisg
Mount Laurel, NJ
A: The maximum ring length depends on the number of multistation access units (maus), the number of wiring closets, the number of maus per wiring closet, and the speed of the network. To calculate the total ring length, the lengths of all the cables between wiring closets connecting the maus to one another are added. From this total value, the length of the shortest cable in the set is subtracted, and the resulting number is referred to as the adjusted ring length.
The maximum lobe length is the distance between any station on the ring and its corresponding mau. Token Ring equipment vendors provide tables illustrating the maximum lobe length, given an adjusted ring length for 4- or 16-megabit-per-second rings using either stp or utp cabling systems. These values will vary from one vendor to another.