Cisco Catalyst 4500 Series, Software Configuration Manual

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Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Chapter 27 Configuring EtherChannel and Link State Tracking
Understanding Link-State Tracking
Displaying EtherChannel Links to VSS
To display the dual-active detection capability of a configured PAgP port channel, enter the
show pagp port_channel_number dual-active command.
The command provides the following information:
• A switch uses enhanced PAgP for dual-active detection.
You should always see Yes after PAgP dual-active diction enabled on a Catalyst 4500 switch.
• The configured PAgP EtherChannel is connected to a Catalyst 6500 switch VSS.
You see N/A below Partner Version if this EtherChannel is not connected to a VSS. Otherwise, you
see the version of enhanced PAgP dual-active detection implemented in the VSS.
• This switch is capable of detecting dual-active scenarios in the connected VSS.
You see Yes below Dual-Active Detect Capable if and only if the configured EtherChannel is
connected to a Catalyst 6500 series VSS that uses the same version of enhanced PAgP dual-active
detection.
Note
You can also see the name of the neighboring switch (Partner Name) and the ports to which this
EtherChannel is connected (Partner Port).
If a Catalyst 4500 switch is connected to a Catalyst 6500 series VSS with the same version of enhanced
PAgP dual-active detection, the switch can detect a dual-active scenario:
Switch# show pagp 1 dual-active
PAgP dual-active detection enabled: Yes
PAgP dual-active version: 1.1
Channel group 1
Dual-Active Partner Partner Partner
Port Detect Capable Name Port Version
Gi6/5 Yes VSS Gi1/8/1 1.1
Gi6/6 Yes VSS Gi2/8/1 1.1
If a Catalyst 4500 switch is not connected to a Catalyst 6500 series VSS, the switch cannot detect a
dual-active scenario:
Switch# show pagp 1 dual-active
PAgP dual-active detection enabled: Yes
PAgP dual-active version: 1.1
Channel group 1
Dual-Active Partner Partner Partner
Port Detect Capable Name Port Version
Gi6/5 No Switch Fa6/5 N/A
Gi6/6 No Switch Fa6/6 N/A
Understanding Link-State Tracking
Link-state tracking, also known as trunk failover, is a feature that binds the link state of multiple
interfaces. For example, link-state tracking provides redundancy in the network when used with server
NIC adapter teaming. When server network adapters are configured in a primary or secondary
relationship known as teaming, if the link is lost on the primary interface, connectivity is transparently
changed to the secondary interface.