Hitachi US7070447-001 - Manual (Page 85)

US7070447-001, Rev 01 12- 1
Chapter 12
FDDI Concepts
FDDI employes a dual ring topology using two counter-rotating fiber rings: a
primary and secondary. Data travels on the primary ring while the secondary
backup ring is utilized if the primary ring fails. The data rate is 100 Mbps based
on a timed-token access method. The total length of the ring can extend up to 200
kilometers with nodes spaced up to 2 kilometers over multimode fiber.
Figure 12-1. HS150 on an FDDI network
Dual Ring
DAS
HS 150
SAS
HS 150
Concentrator