2.5. FC-3: Common Services
The FC-3 level, located at the center of the functional levels, concerns itself with functions spanning multiple N_Ports. The FC-3 level is the single point in the architecture through which all traffic must flow in both directions. The FC-3 level will contain services that are common (available) to all ports on a node.
A node may have several ports. A node may also have several ULPs and FC-4 level mappings. However, there is only one FC-3 Common Services level per node. The FC-3 level can manage a set of tables holding the login information for other active ports. Each port on the FC-3 level knows which ports are busy and which exchanges they are busy with.
Figure 2-12 shows where the FC-3 level fits into the overall ...