Brocade Fabric OS Administrators Guide (Supporting Fabric OS v7.3.0) - Manual (Page 517)

The FC router front domain has a higher node WWN--derived from the FC router--than that of the edge
fabric. Therefore, the FC router front domain initiates the trunking protocol on the EX_Port.
After initiation, the first port from the trunk group that comes online is designated as the master port.
The other ports that come online on the trunk group are considered to be the slave ports. Adding or
removing a slave port does not cause frame drop; however, removing a slave port causes the loss of
frames in transit.
If router port cost is used with EX_Port trunking, the master port and slave ports share the router port
cost of the master port.
The restrictions for EX_Port frame trunking are the same as for E_Ports--all the ports must be adjacent
to each other, in the clearly marked groups on the front of the switch.
ATTENTION
EX_Port trunking should be enabled only if the entire configuration is running Fabric OS v5.2.0 or later.
Refer to Using FC-FC Routing to Connect Fabrics on page 533 for more information about EX_Ports
and the FC router.
Masterless EX_Port trunking
EX_Port trunking is masterless except for EX_Ports on Brocade DCX and DCX 8510 Backbones.
For the Backbones, Virtual Fabrics must be enabled for masterless EX_Port trunking to take effect. For
the fixed-port switches, Virtual Fabrics can be enabled or disabled.
If masterless EX_Port trunking is not in effect and the master port goes offline, the entire EX_Port-
based trunk re-forms and is taken offline for a short period of time. If there are no other links to the edge
fabric from the Backbone, the master port going offline may cause a traffic disruption in the backbone
fabric.
Supported configurations and platforms for EX_Port trunking
EX_Port trunking is a Fiber Channel Routing (FCR) software feature and requires that you have a
Trunking license installed on the FC router and on the edge fabric connected to the other side of the
trunked EX_Ports. The Trunking license is not required for EX_Ports on an ICL.
EX_Port trunking is supported only with Brocade edge fabrics.
You can use EX_Port frame trunking in the following configurations and cases:
• For ports with speeds of 2 Gbps up to a maximum speed of 16 Gbps and trunking over long distance.
• In the edge fabric, when the FC router is connected to a switch that supports eight ports from the
trunkable group.
• When the FC router is connected to an edge fabric through a mix of trunked and nontrunked
EX_Ports; all will share the same front domain.
• In edge-to-edge, backbone-to-edge, and dual-backbone configurations.
Masterless EX_Port trunking has additional configuration requirements. Refer to Masterless EX_Port
trunking on page 517 for these additional requirements.
Masterless EX_Port trunking
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