This article is from the Token Ring FAQ, by James Messer James@NetworkUptime.com with numerous contributions by others.
The design of any network is dependent on limits. In token ring
networks, ring length is a large factor in the physical design of an
error-free network. If the ring is too long, timing and attenuation
issues can create physical-layer errors, disrupting communication
over the entire ring.
In the design of a token ring network, total ring length dictates
the maximum length of cable between the workstation and the MAU.
This value, called the lobe length, can be computed with a series of
tables. These tables are computed for passive MAU networks. Active
MAUs provide capabilities that deviate greatly from the values in
these tables. Consult the manufacturer of the active MAUs for values
that are appropriate for that equipment.