3.17. Hubs

FC_AL hubs connect devices to the loop. It is a simple way to connect participants in a private loop. There are two types of hubs:

  • Passive, which only reacts to ports being inserted into or removed from a loop.

  • Active, which are able to do configuration changes dynamically, based on some controlling protocol.

Some hubs can sense or manage configuration changes in the loop, including:

  • knowing when NL_Ports are added

  • knowing when NL_Ports are removed

  • knowing when address changes occur for an entire set of NL_Ports

  • switching NL_Ports into or out of a loop

Hubs also provide port bypass circuits to “heal” a loop when a device is removed or fails. This allows for less disruption in operations. Hubs help solve the problems of cabling devices ...

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