IBM 866631Y - Netfinity 7100 - 8666 Hardware Maintenance Manual page 20

Ethernet speed 100 Mbps: When this green light is on, the Ethernet speed is
100 Mbps. When the light is off, the Ethernet speed is 10 Mbps.
Processor activity lights: One or more of these green lights are on when there is
microprocessor activity. The number of lights that are on indicates the number of
microprocessors with activity.
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Hardware Maintenance Manual: Netfinity 7100 – Type 8666