Brocade Access Gateway Administrator's Guide (53-1000605-01, October 2007)

Access Gateway Administrator’s Guide 9
53-1000605-01
Access Gateway policies
1
FIGURE 5 Example 1 and 2 Path Failover policy behavior
Failback policy
The Brocade Access Gateway Failback policy automatically reroutes the F_Ports back to the
primary mapped N_Ports as those N_Ports come back online, if failback is enabled for the N_Port.
Only the originally mapped F_Ports fail back. In the case of multiple N_Port failures, only F_Ports
that were mapped to the recovered N_Port experience failback. The remaining F_Ports are not
redistributed among the online N_Ports during the failback; this applies only if the APC is not set.
NOTE
The Failback policy is an N_Port parameter. The Failback policy is enabled by default.
The following sequence describes how a failback event occurs:
1. When an N_Port comes back online, with failBack enabled, the F_Ports that were originally
mapped to it are disabled.
2. The F_Port is reenabled on the primary mapped N_Port.
3. The host establishes a new connection with the fabric.
Example: Failback Policy
In Example 3, the Brocade Access Gateway N_1 remains disabled because the corresponding
F_A1 port is offline. However, N_2 comes back online. See Figure 5 on page 9 for the original
failover scenario.
F_A2
Hosts
Access Gateway
Edge Switch
Fabric
(Switch_A)
enabled
NPIV
F_4
F_3
F_2
F_1
N_1
F_A1
enabled
NPIV
N_3
F_B1
enabled
NPIV
Host_1
Host_2
Host_3
Host_4
F_5
Host_5
F_6
Host_6
F_7
Host_7
F_8
Host_8
Edge Switch
(Switch_B)
N_4
F_B2
enabled
NPIV
N_2
Legend
Physical connection
Mapped online
Failover route online
Original mapped route
(offline)
Example 1
F_A2
Hosts
Access Gateway
Edge Switch
Fabric
(Switch_A)
enabled
NPIV
F_4
F_3
F_2
F_1
N_1
F_A1
enabled
NPIV
N_3
F_B1
enabled
NPIV
Host_1
Host_2
Host_3
Host_4
F_5
Host_5
F_6
Host_6
F_7
Host_7
F_8
Host_8
Edge Switch
(Switch_B)
N_4
F_B2
enabled
NPIV
Example 2
N_2