Specifications

TOKEN RING OVERVIEW
2-2
TOKEN RING TOPOLOGY
The Token Ring topology, or logical shape, is a ring. A ring topology is a
point-to-point network in which the network devices are connected,
machine to machine, in an unbroken unidirectional circle.
The Token Ring topology uses an access method called token passing. No
station may transmit unless that station first possesses the token. Because
of this restriction on transmitting, token rings are deterministic, since it is
possible to accurately calculate the transmission delay times.
Ring topologies can be complex in nature. Although they are relatively
easy to expand, it usually takes careful calculations of physical-design
factors, maximum stations supported and the cabling structure for
example, to keep the network within specification. Most ring topologies
resemble a physical star, but careful examination will reveal a logical ring.
In Figure 2-1, the use of a multi-station access unit (MSAU) with stations
star-wired to it supports the logical ring.
Figure 2-1. Physical Layout of a Token Ring Network
Adding or removing stations on the network is relatively simple and can
be done while the network is active. Software included with the Token
Ring adapter cards in each station on the ring automatically reconfigures
the logical ring in response to the addition or removal of stations on the
ring. Special connectors are used to maintain the integrity of the ring.
Spring loaded shorting bars inside the connector loop back the cable when
the connector is unplugged from a jack.
MSAU
StationStationStationStation
Logical
Ring
Media
Path