3Com CoreBuilder 3500, Руководство по внедрению

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94 C
HAPTER
6: F
IBER
D
ISTRIBUTED
D
ATA
I
NTERFACE
(FDDI)
Nodes
An FDDI network is made up of logically connected nodes . This generic
term is used to refer to any active station or concentrator in an FDDI
network.
■
Station — Any addressable node on an FDDI network that can
transmit, repeat, and receive information. A station contains only one
SMT, and
at least one MAC, one PHY, and one PMD.
■
Concentrator — An FDDI station with additional PHY/PMD entities,
beyond those required for its own connection to an FDDI network.
These additional PHY/PMD entities (M ports) connect other FDDI
stations, including other concentrators, in a tree topology.
Attachments
Attachments refer to how a node, station, or concentrator is connected
to an FDDI network. They are classified as
single attachment and dual
attachment. Concentrators can be classified as null attachment when the
A and B ports are either not present or not used.
■
SAS — Single Attachment Station. A station or concentrator that has
only one physical connection to an FDDI network. The single
attachment cannot accommodate a dual (counter-rotating) ring. A
single attachment station or concentrator has an S port that attaches
to an M port within a concentrator tree.
■
DAS — Dual Attachment Station. Any station or concentrator that
has two physical connections to an FDDI network. This type of
attachment can accommodate a dual (counter-rotating) ring. A dual
attachment station has one A-B port pair; a dual attachment
concentrator has an A-B port pair and at least one M port.