The trunking feature optimizes the use of bandwidth by allowing a group of inter-switch links (ISLs)
to merge into a single logical link. Trunking is automatically implemented for any eligible ISLs after
you install the Brocade ISL Trunking license. The license must be installed on each switch that
participates in trunking. For details on obtaining and installing licensed features, see

Chapter 16,

“Administering Licensing”

Brocade’s trunking feature supports the following trunking configurations:

•

ISL trunking configurations are only applicable to E_Ports.

•

F_Port trunking configurations are only applicable to two separate Fabric OS switches where
all the ports on each switch reside in the same quad and are running at the same speed.

•

EX_Port frame trunking configurations are between an FC router and the edge fabric. See

“EX_Port frame trunking configuration”

on page 474 for additional information about EX_Port

trunking.

•

F_Port Masterless trunking configurations are on edge switches running in Access Gateway
mode where the trunk ports are F_Ports, which are connected as N_Ports.

In a fabric with numerous switches, you can increase the bandwidth between switches by enabling
multiple physical ports to appear as a single port. Enabling multiple physical ports form a trunking
group where the traffic is distributed dynamically and in order at the frame level, thus achieving
greater performance with fewer inter-switch links. Trunking groups are based on the user port
number with contiguous eight ports as one group, such as 0-7, 8-15, and 16-23.

Trunking is performed based on the Quality of Service (QoS) configuration on the master and the
slave ports. That is, in a given trunk group, if there are some ports with QoS enabled and some with
QoS disabled, they form two different trunks, one with QoS enabled and the other with QoS
disabled. For more information on QoS, refer to

“QoS zones”

on page 406.