Configure Etherchannel using PAGP mode Desirable & Auto

Configure Etherchannel using PAGP(Port Aggregation Protocol) mode Desirable/Auto

We configure Etherchannel using PAGP mode Desirable and Auto in the following topology.

Above topology, for both switches we use fastEthernet port 0/1, 0/2, 0/3 & 0/4.
So to configure Etherchannel we need to type the following commands in both switches. But in case of mode, in left switch we use "Desirable" and in right switch we use "Auto".


Switch>en
Switch#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
Switch(config)#interface range fastEthernet 0/1-4
Switch(config-if-range)#channel-group 1 mode desirable

Creating a port-channel interface Port-channel 1

%LINK-5-CHANGED: Interface Port-channel 1, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel 1, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/4, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/4, changed state to up

Switch(config-if-range)#exit
Switch(config)#interface port-channel 1
Switch(config-if)#switchport mode trunk

%LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel 1, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel 1, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to up

Switch(config-if)#


In Right-side Switch type following command in case of mode.

Switch(config)#interface range fastEthernet 0/1-4
Switch(config-if-range)#channel-group 1 mode auto


Thats all. You'll see all ther interfaces become green(UP). Now assign ip and subnet mask into the PCs and do ping to check if the are working or not.