Sun Microsystems 1.0 - Manual (Page 96)

70 SunFDDI/P 1.0 Adapter User’s Guide—May 1997
7
Basic Dual-Ring Network
The dual ring (or dual, counter-rotating ring) is one of the simplest FDDI
network topologies. It clearly illustrates the distinctive ring architecture most
commonly associated with the FDDI standards, as shown in Figure 7-1. Each
station is critical to the operation of the network; therefore, the basic dual-ring
topology is best adapted to small, stable networks that are not subject to
frequent reconfiguration.
In a dual-ring network, dual-attached stations are connected directly to the
primary and secondary rings. Data, and the token that controls the flow of
data, are transmitted in one direction on the primary ring. Data flows in the
other direction on the secondary ring, which is used during ring initialization
and as a backup in case of a ring failure.
Figure 7-1 Basic Dual-Ring Network
Advantages
The primary advantages of the dual-ring network topology are its simplicity
and its ability to recover from simple station and line faults. The secondary
ring provides an effective backup in the event of a single failure in the ring.
FDDI DAS
FDDI DAS
FDDI DAS
FDDI DAS
Primary ring
Secondary ring