3Com CoreBuilder 3500, Руководство по внедрению

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88 C
HAPTER
6: F
IBER
D
ISTRIBUTED
D
ATA
I
NTERFACE
(FDDI)
FDDI Overview
Fiber Distributed Data Interface (FDDI) is a standards-based solution that
provides fast and reliable data transfer on a local area network (LAN).
FDDI technology, which supports data transfer of 100 million bits per
second (100 Mbps), was developed by the American National Standards
Institute (ANSI).
Features FDDI technology:
■
Uses optical fiber as its transmission medium, providing security, low
signal loss, and high bandwidth data communication.
■
Supports simultaneous connection of over 500 nodes on a ring, with
up to 2 kilometers (1.2 miles) between adjacent nodes, and up to
200 kilometers (124 miles) of total fiber length.
■
Uses a token-passing protocol for access to the network.
■
Uses a dual-ring approach: a combination of two independent
counter-rotating rings, each running at a data rate of 100 Mbps.
■
Is the first LAN technology to provide an embedded network
management capability.
Benefits FDDI offers numerous benefits, many of which originate from the use of
fiber-optic cable instead of copper cable.
■
The FDDI standard specifies a data rate of 100 Mbps, which allows
more data to be sent over optical fiber.
■
The distance between nodes using multimode fiber is up to 2 km,
which allows for a larger group of network users.
■
Radio frequency interference (RFI) or electromagnetic interference
(EMI) do not affect fiber-optic cable.
■
Fiber-optic cable uses a dual ring topology that:
■
Provides fault tolerance and isolation.
■
Allows for ring wrapping in the event of a fault.
■
FDDI uses a token access method that:
■
Supports larger networks.
■
Exploits the cable bandwidth more fully.
■
Eliminates collisions, similar to Carrier Sense Multiple
Access/Collision Detect (CSMA/CD).