TABLE OF CONTENTS In the previous chapters of this book, we have been primarily concerned with the N_Ports, and with their interaction with other N_Ports, with an Arbitrated Loop, or with an F_Port providing an interface to a switching Fabric. The internal operation of the switch Fabric has been largely hidden as far as the N_Ports are concerned, a Fibre Channel Fabric operates only as a resource for transporting data to other N_Ports, and for performing services, such as, for example, those described in the Fabric Login section, on page 161. In this chapter, however, we ll examine the internal operation of a switch Fabric, both in terms of the interaction between the various elements of the Fabric, and in terms of the services offered by the Fabric as a whole.
In the simplest cases, a Fabric consists of a single switch. This is, for example, the picture shown in Figure 2.3, on page 17. In this environment, there is no issue of Inter-Switch Links (ISLs), and no issue of inter-switch interoperability. On small-scale networks, where a single switch from a single vendor is used, this configuration is entirely adequate.
Increasingly, however, Fibre Channel installations appear as in Figure 17.1, with multiple switches connected together in a multi-stage Fabric. which may even contain switches from several different vendors.
This more complex Fabric structure has a number of advantages relative to the single-switch Fabric. These advantages of multi-stage fabrics include (1) the capability to support more N_Ports, (2) better...
