Brocade Fabric OS Administrators Guide (Supporting Fabric OS v7.3.0) - Manual (Page 343)

Traffic behavior when failover is enabled or disabled in TI zones TABLE 73
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.
For example, in Figure 32 on page 342, if the dedicated ISL between Domain 1 and Domain 3 goes
offline, then the following occurs, depending on the failover option:
• If failover is disabled for the TI zone, the TI zone traffic is halted until the ISL between Domain 1 and
Domain 3 is back online.
• If failover is enabled for the TI zone, the TI zone traffic is routed from Domain 1 to Domain 3 through
E_Ports "1,2" and "3,10".
NOTE
When TI zone traffic enters the non-TI path, the TI zone traffic continues to flow through that path. In
this example, when the TI zone traffic is routed through E_Ports "1,2" and "3,10", that traffic continues
through the non-TI path between domains 3 and 4, even though the TI path between domains 3 and 4
is not broken.
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 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.
• 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.
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 32
on page 342.
• 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.
Additional considerations when disabling failover
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