Brocade Access Gateway Admin Guide v6.1.0 (53-1000605-02, June 2008)

Access Gateway Administrator’s Guide 13

53-1000605-02

Access Gateway policies

Failover Policy

When a port is configured as an N_Port and if by default, the Failover policy is enabled, F_Ports are

not disabled if its N_Port goes off line. If you specify a Preferred Secondary N_Port for any of the

F_Ports, and if the N_Port goes offline, the F_Ports will fail over to the Preferred Secondary N_Port

and then re-enable. The specified Preferred Secondary N_Port must be online; otherwise, not the

F_Ports will become disabled.

Alternatively, if a Preferred Secondary N_Port is not set for any of F_Ports, the F_Ports will fail over

to other online N_Ports belonging to the same N_Port group, and then re-enable. The FLOGI and

FDISC requests are forwarded from F_Ports through the new N_Port. If multiple N_Ports are

available as candidates for failover, Access Gateway selects one or more N_Ports so that the

F_Ports are evenly balanced across all the N_Ports.

NOTE

Failover of F_Ports to new a N_Port generates a RASLOG message.

The Failover policy allows hosts to automatically remap to an online N_Port if the primary N_Port

goes offline. The Failover policy is enabled (or enforced) during power-up. The Failover policy evenly

distributes the F_Ports that are mapped to an offline N_Port among all the online N_Ports. The

Failover policy is a parameter of each N_Port. By default, the Failover policy is enabled for all

N_Ports.

The following sequence describes how a failover event occurs:

• An N_Port goes offline.

• All F_Ports mapped to that N_Port are disabled.

• If the N_Port Failover policy is enabled, and a Preferred Secondary N_Port is specified for the

F_Port and that N_Port is online, the F_Port fails over to the respective Preferred Secondary

N_Port, and then re-enables.

NOTE

The Preferred Secondary N_Port is defined per F_Port. For example, if two F_Ports are mapped

to a primary N_Port1, you can define a secondary N_Port for one of those F_Ports and not

define a secondary N_Port for the other F_Port. Typically, this is done by the server

administrator. You must determine whether you want to define a preferred secondary map for

each of the servers or just a subset of the servers.

• If the Preferred Secondary N_Port is not online, those F_Ports are disabled.

• If the Preferred Secondary N_Port is not set for any of the F_Ports, those F_Ports will fail over

to other available N_Ports belonging to the same N_Port group, and then re-enables.

• The host establishes a new connection with the fabric.

Example: Failover Policy

This example shows the failover behavior in a scenario where two fabric ports go offline, one after

the other. Note that this example assumes that no Preferred Secondary N_Port is set for any of the

F_Ports.

• First the edge switch F_A1 port goes offline, as shown in Figure 4 on page 14 Example 1 (left),

causing the corresponding Access Gateway N_1 port to be disabled.

The ports mapped to N_1 fail over; F_1 fails over to N_2 and F_2 fails over to N_3.

• Next the F_A2 port goes offline, as shown in Figure 4 on page 14 Example 2 (right), causing the

corresponding Access Gateway N_2 port to be disabled.