SAN Design: March 29, 2001 3:18 pm

2.8STA R TOPOLOGY DESIGN

In the traditional data networking world, star topology network has a core of networking equipment (hubs, switches, and routers) with other equipment radiating out from this. A star topology SAN is fundamentally the same: It contains one or more “core” switches, surrounded by one or more “edge” switches.

FIGURE 8.

Edge

Core

FIGURE 9. Star Topology -- with Core and Edge Switches

There is a difference between a fibre channel star architecture and a traditional data network star. Because the fibre channel r outing protocol FSPF provides superior load sharing characteristics, there could be as many as sixteen core units. If the star were built with future, higher port count products, the count could be even higher. FSPF will distribute connections across all cores more or less evenly.

2.8.1SIMPLE VS. COMPLEX CORES

Each core “unit” in a star SAN can be a single switch (simple), or a group of switches (complex). All of the examples given to this point, there are two cores, each of which is a single switch.

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