Brocade Access Gateway Administrator's Guide - Supporting Fabric OS v5.3.0 (53-1000633-01, June 2007)

6 Access Gateway Administrator’s Guide

53-1000633-01

Failover policy

After ports are initialized, Access Gateway becomes logically transparent to the host and

the fabric, as shown in Figure 4.

FIGURE 4 Host log in request

Failover policy

The Brocade Access Gateway N_Port failover policy allows hosts to automatically remap to an

online N_Port if the N_Port they are connected to goes offline. 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:

1. An N_Port goes offline.

2. All F_Ports mapped to that N_Port are disabled.

3. If the N_Port failover policy is enabled, the disabled F_Ports are remapped to an online N_Port.

The F_Ports are evenly distributed among the remaining online N_Ports.

4. The F_Port is re-enabled on the new N_Port.

5. The host establishes a new connection with the fabric.

COLD FAILOVER

F_Ports that are mapped to an N_Port, that goes offline, will fail over to other N_Ports that are

connected to the same fabric. In the case that an N_Port fails to come online, even once, its

F_Ports will be distributed evenly across all active N_Ports regardless of their attached fabric. Since

Fabric OS 5.3.0 does not support multiple fabrics, this should be not be a likely scenario. Cold

failover is determined for an N_Port under the following condition:

• After the switch comes online, the N_Port fails to successfully login to the enterprise fabric

within 10 seconds. This can happen due to any of the following reasons:

- N_Port is not connected to the enterprise fabric

- NPIV is not enabled on fabric port to which a N_Port is connected

- Fabric Login request from N_Port is rejected by enterprise fabric with a reason other than

“LS_LOGICAL_BUSY”

If at a later time the "dead" N_Port comes online, the failback policy will be enforced for all F_Ports

mapped to the N_Port.