HP StorageWorks 8/80 HP StorageWorks Fabric OS 6.2 administrator guide (5697-0 - Page 344

• If failover is disabled, non-TI zone traffic is blocked because it cannot use the dedicated ISL, which is the lowest cost path. For example, in Figure 44, there is a dedicated path between Domain 1 and Domain 3, and another, non-dedicated, path that passes through Domain 2. If failover is enabled, all traffic will use the dedicated path, because the non-dedicated path is not the shortest path. If failover is disabled, only non-TI zone traffic is blocked because the non-dedicated path is not the shortest path. Domain 1 8 1 9 3 Domain 3 9 14 12 15 7 = Dedicated Path 16 6 = Ports in the TI zone 5 Domain 2 Figure 44 Dedicated path is the shortest path Domain 4 In Figure 45, a dedicated path between Domain 1 and Domain 4 exists, but is not the shortest path. In this situation, if failover is enabled, the TI zone traffic uses the shortest path, even though the E_Ports are not in the TI zone. If failover is disabled, the TI zone traffic stops until the dedicated path is configured to be the shortest path. Domain 1 8 1 9 3 Domain 3 9 14 12 15 16 = Dedicated Path = Ports in the TI zone Domain 2 Figure 45 Dedicated path is not the shortest path 7 6 5 Domain 4 NOTE: For information about setting or displaying the FSPF cost of a path, see the linkCost and topologyShow commands in the Fabric OS Command Reference. Traffic Isolation Routing over FC routers This section describes how TI zones work with Fibre Channel routing (TI over FCR). See Chapter 17, "Using the FC-FC routing service" on page 367 for information about FC routers, phantom switches, and the FC-FC Routing Service. Some VE_Port-based features, such as tape pipelining, require the request and corresponding response traffic to traverse the same VE_Port tunnel across the metaSAN. To ensure that the request and response traverse the same VE_Port tunnel, you must set up Traffic Isolation zones in the edge and backbone fabrics. 342 Optimizing fabric behavior