Cisco Catalyst 4500 Series, Software Configuration Manual

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5-52
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Chapter 5 Configuring Virtual Switching Systems
Configuring a VSS
Configuring Dual-Active Detection
The following sections describe how to configure dual-active detection:
•
Configuring Enhanced PAgP Dual-Active Detection, page 5-52
• Configuring Fast-Hello Dual-Active Detection, page 5-53
•
Displaying Dual-Active Detection, page 5-54
Configuring Enhanced PAgP Dual-Active Detection
If enhanced PAgP is running on the MECs between the VSS and its access switches, the VSS can use
enhanced PAgP messaging to detect a dual-active scenario.
By default, PAgP dual-active detection is enabled. However, the enhanced messages are only sent on port
channels with trust mode enabled (see the trust mode description in the note).
Note
Before changing PAgP dual-active detection configuration, ensure that all port channels with trust mode
enabled are in administrative down state. Use the
shutdown command in interface configuration mode
for the port channel. Remember to use the no shutdown command to reactivate the port channel when
you are finished configuring dual-active detection.
To enable or disable PAgP dual-active detection, perform this task:
You must configure trust mode on the port channels that will detect PAgP dual-active detection. By
default, trust mode is disabled.
Note
If PAgP dual-active detection is enabled, you must place the port channel in administrative down state
before changing the trust mode. Use the
shutdown command in interface configuration mode for the port
channel. Remember to use the no shutdown command to reactivate the port channels when you are
finished configuring trust mode on the port channel.
To configure trust mode on a port channel, perform this task:
This example shows how to enable PAgP dual-active detection:
Switch(config)# interface port-channel 20
Switch(config-if)# shutdown
Switch(config-if)# exit
Switch(config)# switch virtual domain 100
Command Purpose
Step 1
Switch(config)#
switch virtual domain
domain_id Enters virtual switch submode.
Step 2
Switch(config-vs-domain)# dual-active detection pagp
Enables sending of the enhanced PAgP messages.
Command Purpose
Step 1
Switch(config)# switch virtual domain domain_id
Enters virtual switch submode.
Step 2
Switch(config-vs-domain)# dual-active detection pagp
trust channel-group group_number
Enables trust mode for the specified port channel.