Brocade Communications Systems 53-1003126-02 Persistent ALPA policy

3. The Port Grouping policy must be enabled to enable Device Load Balancing. Enter the ag --

policyshow command to determine if the Port Grouping policy is enabled. If it is not enabled, enter

ag --policyenable pg to enable this policy.

4. Enter the ag --policyenable wwnloadbalance command to enable the Device Load Balancing

policy. Because Fibre Channel devices are identified by their WWNs, CLI commands use device

WWNs.

Before disabling this policy, you should save the configuration using the configUpload command in

case you need this configuration again.

1. Connect to the switch and log in using an account assigned to the admin role.

2. Enter the ag --policydisable wwnloadbalance command to disable the Device Load Balancing

policy.

3. Enter the ag --policyshow command to determine the current status of the Device Load Balancing

policy.

• The Device Load Balancing policy should be enabled on the edge AG of a cascaded AG

configuration.

• The Device Load Balancing policy is not applicable on a port group when the APC policy or

Automatic Login Balancing are enabled.

• If a device is mapped to a port that is currently part of a trunk, then the device will use that trunk.

When trunking is used with the Device Load Balancing policy, then the load on each trunk will be

proportional to the number of ports in that trunk. Use the ag -show command to determine the

devices using a particular trunk.

• When using the Device Load Balancing policy, make sure that all ports in the port group have the

same NPIV login limit. If some ports have a lower login limit than the other ports, and there are many

logins to the group, some devices will repeatedly attempt to connect to the device with the lower limit

(because it has the fewest logins) and fail to connect.

Persistent ALPA policy

The Persistent ALPA policy is meant for host systems with operating systems that cannot handle

different PID addresses across login sessions when booting over a SAN. The Persistent ALPA policy for

switches in Access Gateway mode allows you to configure the AG module so that the host is more likely

to get the same PID when it logs out of and into the same F_Port. Because the Arbitrated Port Loop

Address (ALPA) field makes up a portion of the PID, the PID may change across switch or server power

cycles. This policy, if enabled, helps reduce the chances of a different PID being issued for the same

host.

The benefit of this policy is that it ensures that a host has the same ALPA on the F_Ports through the

host power cycle. You can also achieve the same behavior and benefit by setting the same policy in the

main (core) fabric. When this policy is enabled, AG will request the same ALPA from the core fabric.

However, depending on the fabric, this request may be denied. When this occurs, the host is assigned a

different ALPA. The following modes deal with this situation:

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