Fabric OS Administrator’s Guide 269
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Traffic Isolation Zoning overview 12
For example, in Figure 34 on page 268, if the dedicated ISL between Domain 1 and Domain 3 goes
offline, then the following occurs, depending on the failover option:
•If failover is enabled for the TI zone, the traffic is routed from Domain 1 to Domain 3 through
E_Ports “1,2” and “3,10”.
•If failover is disabled for the TI zone, the traffic is halted until the ISL between Domain 1 and
Domain 3 is back online.
If the non-dedicated ISL between Domain 1 and Domain 3 goes offline, then the following occurs,
depending on the failover option:
•If failover is enabled for the TI zone, non-TI zone traffic is routed from Domain 1 to Domain 3
through the dedicated ISL.
NOTE
When non-TI zone traffic enters the TI path, the non-TI zone traffic continues to flow through
that path. In this example, when the non-TI zone traffic is routed through E_Ports “1,1” and
“3,9”, that traffic continues through E_Ports “3,12” and “4,7”, even though the non-dedicated
ISL between domains 3 and 4 is not broken.
•If failover is disabled for the TI zone, non-TI zone traffic is halted until the non-dedicated ISL
between Domain 1 and Domain 3 is back online.

Additional considerations when disabling failover

If failover is disabled, be aware of the following considerations:
•This feature is intended for use in simple linear fabric configurations, such as that shown in
Figure 34 on page 268.
•Ensure that there are non-dedicated paths through the fabric for all devices that are not in a TI
zone.
•If you create a TI zone with just E_Ports, failover must be enabled. If failover is disabled, the
specified ISLs will not be able to route any traffic.
•If the path between devices in a TI zone is broken, no inter-switch RSCNs are generated. Each
switch that is part of the TI zone generates RSCNs to locally attached devices that are part of
the TI zone and are registered to receive RSCNs.
•Ensure that there are multiple paths between switches.
Disabling failover locks the specified route so that only TI zone traffic can use it. Non-TI zone
traffic is excluded from using the dedicated path.
•It is recommended that TI zone definitions and regular zone definitions match.
TABLE 52 Comparison of traffic behavior when failover is enabled or disabled in TI zones
Failover enabled Failover disabled
If the dedicated path is not the shortest path or if the
dedicated path is broken, the TI zone traffic will use a
non-dedicated path instead.
If the dedicated path is not the shortest path or if the
dedicated path is broken, traffic for that TI zone is
halted until the dedicated path is fixed.
Non-TI zone traffic will use the dedicated path if no
other paths through the fabric exist, or if the
non-dedicated paths are not the shortest paths.
Non-TI zone traffic will never use the dedicated path,
even if the dedicated path is the shortest path or if
there are no other paths through the fabric.