EtherChannel | Lag port or link aggregation configuration on cisco switch in GNS3

how to configure link aggregation on Cisco

Port channel interface:

Using port channel interface group you can perform the same configuration at once, you need to configure all your configuration on your channel group and then it will replicate all your configuration on all the interface that you have added to that channel group.

With port aggregation you can utilize your interface with maximum throughput and speed. Suppose you have two redundant interfaces between your switches, using channel group you can utilize both interfaces at once. If you have two links of 1G each between two switches, you don’t get the 2G bandwidth/speed with channel group but you can used both link as once. In absence of channel group spaining tree protocol block one of link and use only one link/interface at a time. But with port channel if you have two PC with switch as shown in figure, then PC1 may use interface 0/1 and PC2 may use other interface a, in this way you can utilize both of your interfaces. EtherChannel provides automatic recovery for the loss of a link by redistributing the load across the remaining links. If a link fails, EtherChannel redirects traffic from the failed link to the remaining links in the channel without intervention.
 How to configure Port channel group:

interface range f1/0 - 1
channel group 1 mode on
 For configuring different setting with port channel you can use following configurations:

interface port-channel 1
switchport speed 4000
no shut

When you created the channel group then it is necessary that you should perform all your configuration through that channel-group if you do some configuration on individual interfaces then it will give you error of ”mismatch configuration”..