Cisco Nexus 5000 Series Switch CLI Software Configuration Guide (OL-16597-01, July 2009)

The preferred configuration on the Cisco Nexus 5000 Series switches is that one side of the trunk is set to
auto and the other is set to on.
When connected to a third-party switch, the trunk mode configuration has no effect. The ISL is always
in a trunking disabled state.
Note
Configuring Trunk Mode
To configure trunk mode, perform this task:
Procedure
PurposeCommand or Action
Enters configuration mode.switch# configuration terminal
Step 1
Configures the specified interface.
switch(config)# interface fc slot/port
Step 2
Enables (default) the trunk mode for the
specified interface.
switch(config-if)# switchport trunk mode
on
Step 3
Disables the trunk mode for the specified
interface.
switch(config-if)# switchport trunk mode
off
Step 4
Configures the trunk mode to auto mode, which
provides automatic sensing for the interface.
switch(config-if)# switchport trunk mode
auto
Step 5
About Trunk-Allowed VSAN Lists
Each Fibre Channel interface has an associated trunk-allowed VSAN list. In TE-port mode, frames are
transmitted and received in one or more VSANs specified in this list. By default, the complete VSAN range
(1 through 4093) is included in the trunk-allowed list.
The common set of VSANs that are configured and active in the switch are included in the trunk-allowed
VSAN list for an interface, and they are called allowed-active VSANs. The trunking protocol uses the list of
allowed-active VSANs at the two ends of an ISL to determine the list of operational VSANs in which traffic
is allowed.
In the following figure, switch 1 has VSANs 1 through 5, switch 2 has VSANs 1 through 3, and switch 3 has
VSANs 1, 2, 4, and 5 with a default configuration of trunk-allowed VSANs. All VSANs configured in all
Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
510 OL-16597-01
Configuring VSAN Trunking
Configuring Trunk Mode