Installation guide

4-80 Cisco 4000 Series Installation Guide
Network Connection Considerations
Figure 4-35 Multimode FDDI Network Interface Connector, MIC Type
The port labeled PHY-A is the bottom port (see Figure 4-33 and Figure 4-36), and port
labeled PHY-B is the top port on both the multimode and single-mode modules. To connect
to another dual-attachment station, connect PHY-A on the module to PHY-B on the other
DAS and PHY-B on the module to PHY-A on the other DAS.
The standard connection scheme for a dual-attachment station dictates that the primary ring
signal enters the router on the PHY-A receive port and returns to the primary ring from the
PHY-B transmit port. (See Figure 4-37.) The secondary ring signal comes into the router
on the PHY-B receive port and returns to the primary ring from the PHY-A transmit port.
Failure to observe this relationship in making your network connections will prevent the
FDDI interface from initializing.
The PHY-S port of the single-attachment module can be connected through a concentrator
to a single-attachment ring or directly to another device. (See Figure 4-38.)
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