Configuring a Port Channel Interface

Port-Channel interfaces are logical interfaces assigned to EtherChannel bundles. This lab will discuss and demonstrate the configuration and verification of Port-Channel interfaces.

Real World Application & Core Knowledge

If you completely the previous three labs then you should be quite familiar with EtherChannel technology by now. As stated in the previous labs that when you bundle multiple links into an etherchannel they are represented by a single logical link, or you can say a single logical interface which is known as a port-channel interface.

Port-Channel interfaces are classified as “virtual links” which will represent the path that traffic traverses when going through an etherchannel bundle towards a specific destination.

Any commands issued in Port-Channel configuration mode apply to all links in the channel-group.

In this lab you will familiarize yourself with the following commands;

Command Description
interface port-channel # When executing this command in global configuration mode you will be placed in Port-Channel interface configuration mode which configures all bundled links in the specific Ether-Chanel group number simultaneously.

Lab Prerequisites

  • If you are using GNS3 than load the Free CCNA Workbook GNS3 topology than start devices; SW1 and SW2.
  • Establish a console session with devices SW1 and SW2 than configure the devices respected hostname(s).
  • Configure interfaces Fa0/10, Fa0/11 and Fa0/12 on both SW1 and SW2 as an unconditional EtherChannel using channel-group number 1.

Lab Objectives

  • Configure interface Port-Channel1 on both SW1 and SW1 to trunk then verify that the changes you’ve made on the Port-Channel interface have propagated to the bundled links; Fa0/10, Fa0/11 and Fa0/12.
  • Shutdown interface Port-Channel1 and verify that the command issued in Port-Channel1 interface configuration mode is executed on the channel-group bundled links.

Lab Instruction

Step 1. – Configure interface Port-Channel1 on both SW1 and SW1 to trunk then verify that the changes you’ve made on the Port-Channel interface have propagated to the bundled links; Fa0/10, Fa0/11 and Fa0/12.

Navigate to the Port-Channel1 interface and configure the interface to trunk; afterward verify that the configuration has propagated to the bundled interfaces as shown below;

SW1 con0 is now available



Press RETURN to get started.



SW1>enable
SW1#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
SW1(config)#interface port-channel 1
SW1(config-if)#switchport mode trunk
%EC-5-UNBUNDLE: Interface Fa0/10 left the port-channel Po1
%EC-5-UNBUNDLE: Interface Fa0/11 left the port-channel Po1
%EC-5-UNBUNDLE: Interface Fa0/12 left the port-channel Po1
%EC-5-BUNDLE: Interface Fa0/12 joined port-channel Po1
%EC-5-BUNDLE: Interface Fa0/11 joined port-channel Po1
%EC-5-BUNDLE: Interface Fa0/10 joined port-channel Po1
%DTP-5-TRUNKPORTON: Port Fa0/10-12 has become dot1q trunk
%LINK-3-UPDOWN: Interface Port-channel1, changed state to up
SW1(config-if)#end
SW1#show run
!
interface FastEthernet0/10
 switchport mode trunk
 channel-group 1 mode on
!
interface FastEthernet0/11
 switchport mode trunk
 channel-group 1 mode on
!
interface FastEthernet0/12
 switchport mode trunk
 channel-group 1 mode on
!
SW1#

As shown above when the trunk was configured on the Port-Channel 1 interface, all interface members of the channel-group were removed from the group, configuration applied then re-added to the channel-group.


Step 2. – Shutdown interface Port-Channel1 and verify that the command issued in Port-Channel1 interface configuration mode is executed on the channel-group bundled links as shown below;

SW1#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
SW1(config)#interface port-channel 1
SW1(config-if)#shutdown
%EC-5-UNBUNDLE: Interface Fa0/10 left the port-channel Po1
%EC-5-UNBUNDLE: Interface Fa0/11 left the port-channel Po1
%EC-5-UNBUNDLE: Interface Fa0/12 left the port-channel Po1
%DTP-5-NONTRUNKPORTON: Port Fa0/10-12 has become non-trunk
SW1(config-if)#
%LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel1, changed state to down
%LINK-5-CHANGED: Interface FastEthernet0/10, changed state to administratively down
%LINK-5-CHANGED: Interface FastEthernet0/11, changed state to administratively down
%LINK-5-CHANGED: Interface FastEthernet0/12, changed state to administratively down
SW1(config-if)#
%LINK-5-CHANGED: Interface Port-channel1, changed state to administratively down
SW1(config-if)#do show run
!
interface FastEthernet0/10
 switchport mode trunk
 shutdown
 channel-group 1 mode on
!
interface FastEthernet0/11
 switchport mode trunk
 shutdown
 channel-group 1 mode on
!
interface FastEthernet0/12
 switchport mode trunk
 shutdown
 channel-group 1 mode on
!
SW1#
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