9000

Chapter 2 39

Installing the HP EISA FDDI/9000 Adapter

Connecting the Adapter to the Network

Figure 2-5 DAS MIC Fiber Connections

Connecting Directly to the Dual Ring

This adapter can be connected directly to the dual ring by connecting the

A and B ports of its neighbors.

During normal operation of a dual ring with no faults, each station

receives and transmits all trafﬁc on the primary ring, while the

secondary ring is idle. If a station is turned off or disconnected from the

ring, neighboring stations detect this as a fault or discontinuity, and

wrap the trafﬁc onto the secondary ring, thus keeping remaining stations

in communication. However, if a second fault occurs during this time, the

ring could become segmented, separating groups of stations into

independent rings. An Optical Bypass Switch (OBS) can be used to

bypass a station that is turned off or disconnected, protecting against

multiple faults on a dual ring. Figure 2-6 shows the connection of the

OBS to a dual ring.

(1)

(2)

(3)

(4)

MIC Ports

Optical Bypass

EISA Connector

MIC port on adapter

Key located in slot

MIC

To M port of

single-attachment

concentrator

Faceplate