Cabling and Verifying Media Cards
FDDI attachment options
GRF 400/1600 Getting Started - 1.4 Update 2
October, 1998
5-19
Single attach - M and S interfaces
Single attach FDDI interfaces can be either master (M) or slave (S) interfaces.
They require a cable with a corresponding master or slave connector. Single attach cables have
an “M” connector at one end and an “S” connector on the other. With no key installed, “M” and
“S” connectors both fit the FDDI interface.
Figure 5-12 show the relationship between master and slave interfaces.
Figure 5-12. Single attach FDDI interface using master / slave keys
A single attach FDDI interface on the GRF is a master interface when it directly connects to a
workstation. It is a slave interface when connected to the master interface of a FDDI
concentrator. Such concentrators connect, in turn, to the slave interfaces of single-attach
workstations.
Dual attach - A and B interfaces
Dual attach interfaces connect to form two unbroken counter-rotating rings, one being a
redundant backup. Each interface, or station, has both an “A” and a “B” interface. Dual attach
cables have an “A” connector on one end and a “B” connector on the other.
The “A” interface connects a station to its downstream neighbor; the “B” interface connects a
station to its upstream neighbor. To create a logical ring, “A” must connect to “B”, “B” must
connect to “A”. Otherwise, the network does not operate as a logical ring and segments into
unconnected suborns. Figure 5-13 illustrates a logical ring.
Figure 5-13. Dual attach FDDI interface using A / B keys
Single attach:
M
FDDI
Concentrator
S
M
S
M
S
M
S
S
FDDI
A0
B0
A1
B1
M
S
M
S
M
M
M
M
S
S
S
FDDI
A0
B0
A1
B1
Dual attach:
Logical ring
A
A
Station
1
B
B
A
A
Station
2
B
B
A
A
Station
N...
A
A
B
B
Station
3
A
A
B
B
B
B
. . .
