3.18 Hub Topologies

only for RuBoard - do not distribute or recompile

There will be more information about hubs in Chapter 4. For now, to demonstrate a couple of topologies using hubs see Figures 3-24 and 3-25.

Figure 3-24. Cascaded Shortwave Hub Topology

Figure 3-25. Cascaded Longwave Hub Topology

3.18.1 Cascading Shor twave Hubs

A server with an FC-AL shortwave host bus adapter (HBA) can connect to an FC-AL hub 500 meters away. Each of the 10 ports on the hub can connect to an FC-AL device up to 500 meters away.

Cascaded hubs use one port on each hub for the hub-to-hub connection and this increases the potential distance between nodes in the loop an additional 500 meters. In this topology the overall distance is 1500m. Both hubs can support other FC-AL devices at their physical locations. Stated distances assume a 50 micron multimode cable.

3.18.2 Cascading Longwave Hubs

Cascaded FC-AL, non-OFC, longwave hubs use the long-wave port for the hub-to-hub connection. Ports 1 through 9 on each longwave hub are for connections to FC-AL devices. When cascading longwave hubs, only use the longwave port on each hub to connect the hubs. The overall distance in this topology is 11,000 meters. There is 500 m from the server to the first hub, plus 10,000 m between the two longwave hubs, plus 500 m from the second hub to the final device.

only for RuBoard - do not distribute or recompile