Brocade Access Gateway Administrator's Guide (Supporting Fabric OS v7.3.0) - Manual (Page 55)

How port groups work
Create port groups using the ag --pgcreate command. This command groups N_Ports together as "port
groups." By default, any F_Ports mapped to the N_Ports belonging to a port group will become
members of that port group. Port grouping fundamentally restricts failover of F_Ports to the N_Ports that
belong to that group. For this reason, an N_Port cannot be member of two port groups. The default PG0
group contains all N_Ports that do not belong to any other port groups.
The figure below shows that if you have created port groups and then an N_Port goes offline, the
F_Ports being routed through that port will fail over to any of the N_Ports that are part of that port group
and are currently online. For example, if N_Port 4 goes offline, then F_Ports 7 and 8 are routed through
to N_Port 3 as long as N_Port 3 is online because both N_Ports 3 and 4 belong to the same port group,
PG2. If no active N_Ports are available, the F_Ports are disabled. The F_Ports belonging to a port
group do not fail over to N_Ports belonging to another port group.
FIGURE 9 Port grouping behavior
When a dual redundant fabric configuration is used, F_Ports connected to a switch in AG mode can
access the same target devices from both of the fabrics. In this case, you must group the N_Ports
How port groups work
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