S e n d d o c u m e n t a t i o n c o m m e n t s t o m d s f e e d b a c k - d o c @ c i s c o . c o m
The preferred configuration on the Cisco MDS 9000 Family switches is one side of the trunk set to auto
and the other 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.
Configuring Trunk Mode
To configure trunk mode, follow these steps:
switch# config t
switch(config)# interface fc1/1
switch(config-if)# switchport trunk mode on
switch(config-if)# switchport trunk mode off
switch(config-if)# switchport trunk mode auto
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 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.
VSANs 1, 2, 4, and 5 with a default configuration of trunk-allowed VSANs. All VSANs configured in
all three switches are allowed-active. However, only the common set of allowed-active VSANs at the
ends of the ISL become operational as shown in
Cisco MDS 9000 Family CLI Configuration Guide
15-4, switch 1 has VSANs 1 through 5, switch 2 has VSANs 1 through 3, and switch 3 has
Enters configuration mode.
Configures the specified interface.
Enables (default) the trunk mode for the
Disables the trunk mode for the specified
Configures the trunk mode to auto mode, which
provides automatic sensing for the interface.
OL-16184-01, Cisco MDS SAN-OS Release 3.x