
Configuring Line Services
2-6 114078 Rev. A
The FDDI Standard
FDDI uses a dual counter-rotating ring topology for fault recovery and
sophisticated encoding techniques to ensure data integrity. The FDDI standard
specifies that the total length of the fiber-optic cabling used to connect the nodes
may not exceed 200 km, or 100 km per ring.
The FDDI standards consist of the following entities:
• Physical Layer Media Dependent (PMD)
The PMD standard defines the physical characteristics of the media interface
connectors and the cabling, and the services necessary for transmitting signals
between nodes.
• Physical Layer Protocol (PHY)
The PHY standard defines the rules for encoding and framing data for
transmission, clocking requirements, and line states.
• Media Access Control (MAC)
The MAC standard defines the FDDI timed-token protocol, frame and token
construction and transmission on the FDDI ring, ring initialization, and fault
isolation.
• Station Management (SMT)
The SMT standard defines the protocols for managing the PMD, the PHY, and
the MAC components of FDDI. The SMT protocols monitor and control the
activity of each node on the ring.
Figure 2-4 shows the relationship of the four FDDI standards.
Figure 2-4. Relationship of FDDI Standards
Media Access Control (MAC)
Station
Management
(SMT)
Physical Layer Protocol (PHY)
Physical Layer Media Dependent (PMD)
LS0006A
Kommentare zu diesen Handbüchern