Cisco Catalyst 4500 Series Command Reference Guide

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Catalyst 4500 Series Switch Cisco IOS Command Reference—Release IOS XE 3.4.0SG and IOS 15.1(2)SG)
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Chapter 2 Cisco IOS Commands for the Catalyst 4500 Series Switches
dual-active detection (virtual switch)
dual-active detection (virtual switch)
To enable and configure dual-active detection, use the dual-active detection command in virtual switch
configuration submode. To disable dual-active detection, use the no form of this command.
dual-active detection {pagp [trust channel-group num]}
no dual-active detection {pagp}
Syntax Description
Defaults bfd and pagp are enabled.
trust is disabled.
Command Modes Virtual switch configuration submode (config-vs-domain)
Command History
Usage Guidelines If PAgP is running on the MECs between the VSS and its access switches, the VSS can use enhanced
PAgP messaging to detect dual-active scenario. The MEC must have links from both chassis of the VSS
to the access switch. By default, PAgP dual-active detection is enabled. However, the enhanced messages
are only sent on channel groups with trust mode enabled.
If you configure the fast hello dual-active detection mechanism, you must also configure dual-active
interface pairs to act as fast hello dual-active messaging links.
When you enter the optional trust channel-group num keywords and argument, the following applies:
• You can configure trust mode on a port channel even if there are no interfaces on the port channel
or the port channel is a protocol type other than PAgP. The trust mode status is displayed in the show
pagp dual-active command output, but no interfaces are displayed.
• Configuring trust mode requires that the port channel exists. If the port channel does not exist, the
following error message is displayed:
Router(config-vs-domain)# dual-active trust pagp channel-group 30
Port-channel 30 not configured
• If a trusted port is deleted, the trust-mode configuration is deleted and the following warning
message is displayed:
Port-channel num is a trusted port-channel for PAgP
dual-active detection. Restricting this
port-channel has deleted the dual-active trust
pagp Configures Port Aggregation Protocol (PAgP) as the dual-active
detection method. Default: enabled.
trust channel-group
num
(Optional) Specifies the EtherChannel/port bundling to be used for
PAgP dual-active detection. Range: 1 to 256. Default: disabled.
Release Modification
Cisco IOS XE 3.4.0SG and
15.1(2)SG
Support for this command was introduced on the Catalyst 4500 series
switch.

Cisco Catalyst 4500 Series Specifications

General

Series	Catalyst 4500 Series
Category	Switch
Layer Support	Layer 2, Layer 3
Form Factor	Modular chassis
Stackable	No
Chassis Slots	3, 6, 7, 10
Power Supply Options	AC, DC
Redundancy	Power supply, Supervisor engine
Network Management	Cisco IOS Software CLI, SNMP, Cisco Prime Infrastructure
Features	Security, QoS
Port Density	Up to 384 ports per chassis
Security Features	802.1X, ACLs, DHCP Snooping, Dynamic ARP Inspection, IP Source Guard
Supervisor Engine	8-E