SECURING FIBRE CHANNEL FABRICS - Brocade

FC Fabric Features and ServicesAs can be seen from Table 6, the number of ISLs required increasessignificantly for each additional switch. It is important to note thateach ISL also requires two ports; one at each end switch. Eventually,there will be more ports using ISLs than actual hosts and storagedevices in the fabric and switches simply won't have enough ports toconnect all the switches.To improve scalability, a mesh topology can also be constructed as apartial mesh, as shown in Figure 19. In this case, most, but not all,switches are connected to all other switches in the fabric. This is amore scalable alternative to a full mesh design, but at the expense ofpath redundancy and possibly performance.Switch ASwitch BSwitch CSwitch FSwitch DSwitch EFigure 12. Partial mesh topologyCore-Edge TopologyThe core-edge topology is the most commonly implemented and it representsthe best compromise among redundancy, scalability,performance, and cost. There are several variations of a core-edgearchitecture.Pure core-edge architectures are designed so that all of the trafficmust go through the core switch, hence only other switches can beconnected to a core switch. The hosts and storage devices are connectedto edge switches, as shown in Figure 20. In reality, most coreedgeimplementations actually connect some storage or host devicesto core switches to maximize the cost efficiency of the fabric and makethe best utilization of available ports, as shown in Figure 21.Securing Fibre Channel Fabrics 39