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About the Trunking Protocol
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 .
About the Trunking Protocol
The trunking protocol is important for E-port and TE-port operations. It supports the following:
•
•
•
By default, the trunking protocol is enabled. If the trunking protocol is disabled on a switch, no port on
that switch can apply new trunk configurations. Existing trunk configurations are not affected—the TE
port continues to function in trunk mode, but only supports traffic in VSANs that it negotiated with
previously (when the trunking protocol was enabled). Also, other switches that are directly connected to
this switch are similarly affected on the connected interfaces. In some cases, you may need to merge
traffic from different port VSANs across a non-trunking ISL. If so, disable the trunking protocol.
To avoid inconsistent configurations, disable all E ports with a shutdown command before enabling or
Tip
disabling the trunking protocol.
Enabling or Disabling the Trunking Protocol
To enable or disable the trunking protocol, follow these steps:
Command
Step 1
switch# config t
Step 2
switch(config)# no trunk protocol enable
switch(config)#
switch(config)# trunk protocol enable
switch(config)#
Configuring Trunk Mode
By default, the trunk mode is enabled in all Fibre Channel interfaces. However, the trunk mode
configuration takes effect only in E-port mode. You can configure the trunk mode as on (enabled), off
(disabled), or auto (automatic). The default trunk mode is on. The trunk mode configuration at the two
ends of an ISL, between two switches, determine the resulting trunking state of the link and the port
modes at both ends (see
Table 12-2
Your Trunk Mode Configuration
Switch 1
On
Off
Auto
Cisco MDS 9000 Family Configuration Guide
12-2
Dynamic negotiation of operational trunk mode.
Selection of a common set of trunk-allowed VSANs.
Detection of a VSAN mismatch across an ISL.
Table
Trunk Mode Status Between Switches
Switch 2
Auto or on
Auto, on, or off
Auto
12-2).
Resulting State and Port Mode
Trunking State
Trunking (EISL)
No trunking (ISL)
No trunking (ISL)
Chapter 12
Configuring Trunking
Purpose
Enters configuration mode.
Disables the trunking protocol.
Enables trunking protocol (default).
Port Mode
TE port
E port
E port
OL-6973-03, Cisco MDS SAN-OS Release 2.x
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