Brocade Access Gateway Administrator's Guide Supporting Fabric OS v7.0.0 (53-1002156-01, April 2011)

52 Access Gateway Administrator’s Guide
53-1002156-01
Trunking in Access Gateway mode
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ag --reliabilitycounterset “count”
You can view counter settings using the following command.
ag --reliabilitycountershow
Considerations for Failback policy disable on unreliable links
Consider the following when an N_Port link becomes reliable again after being unreliable:
• Preferred N_Port settings are enforced.
• If failback is enabled, configured F_Ports will fail back to the N_Port.
• If the configured F_Ports are offline, they will go back online.
• If Device Load Balancing is enabled, rebalancing occurs.
Trunking in Access Gateway mode
The hardware-based Port Trunking feature enhances management, performance, and reliability of
Access Gateway N_Ports when they are connected to Brocade fabrics. Port trunking combines
multiple links between the switch and AG module to form a single, logical port. This enables fewer
individual links, thereby simplifying management. This also improves system reliability by
maintaining in-order delivery of data and avoiding I/O retries if one link within the trunk fails.
Equally important is that framed-based trunking provides maximum utilization of links between the
AG module and the core fabric.
Trunking allows transparent failover and failback within the trunk group. Trunked links are more
efficient because of the trunking algorithm implemented in the switching ASICs that distributes the
I/O more evenly across all the links in the trunk group.
Trunking in Access Gateway is mostly configured on the Edge switch. To enable this feature, you
must install the Brocade ISL license on both the Edge switch and the module running in AG mode
and ensure that both modules are running the same Fabric OS version. If a module already has an
ISL trunking license, no new license is required. After the trunking license is installed on a switch in
AG mode and you change the switch to standard mode, you can keep the same license.
NOTE
N_Port trunking is not supported to HBAs connected to switches running in Access Gateway mode.
N_Port trunking is only supported for HBAs connected to switches running in Native mode.
How trunking works
Trunking in Access Gateway mode provides a trunk group between N_Ports on the AG module and
F_Ports on the Edge switch module. With trunking, any link within a trunk group can go offline or
become disabled, but the trunk remains fully functional and no reconfiguration is required.
Trunking prevents reassignments of the port ID when N_Ports go offline.