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About Trunking Protocol
About 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 will not be affected--the
TE port continues to function in trunk mode, but only supports traffic in VSANs that it negotiated
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, shut all E ports before enabling or disabling the trunking protocol.
Configuring Trunk Modes
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.
Table 13-1
Your Trunk Mode Configuration
Switch 1
On
Off
Auto
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-Allowed VSAN List
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.
Cisco MDS 9000 Fabric Manager Switch Configuration Guide
13-2
Dynamic negotiation of operational trunk mode.
Selection of a common set of trunk-allowed VSANs.
Detection of a VSAN mismatch across an ISL.
Trunk Mode Status Between Switches
Chapter 13
Resulting State and Port Mode
Switch 2
Auto or on
Auto, on, or off
Auto
Configuring Trunking
OL-7753-01
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