HP StorageWorks Fabric OS 6.2 administrator guide (5697-0016, May 2009)

342 Optimizing fabric behavior
• 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.
Figure 44 Dedicated path is the shortest path
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.
Figure 45 Dedicated path is not the shortest path
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.
7
12
3
14
15
16
Domain 1 Domain 3
Domain 4
Domain 2
8
19
6
9
5
= Dedicated Path
= Ports in the TI zone
7
12
3
14
15
16
Domain 1 Domain 3
Domain 4
Domain 2
8
19
6
9
5
= Dedicated Path
= Ports in the TI zone