getting error of invalid input for switchport trunk

[GuriSingh]

i am getting this error of invalid input for switchport in config terminal of switchport fa0/0 connected router

  

[Flavio Miranda]

@GuriSingh 

 This is a layer3 port and does not accept layer2 features

[GuriSingh]

is there any way I can convert it into a switchport or enable the data transfer with the main campus

[Flavio Miranda]

Not possible to convert. Is It a switch IOS or Router IOS?

 Gns3 is very bad for layer2.

[GuriSingh]

this one is a router IOS

[Flavio Miranda]

That´s should be the problem. As a router, you dont have layer2 feature. 

You need to play with L2 IOU or you can try EVE, which is much better than GNS3 and also free

[MHM Cisco World]

there is L2 IOU 

check google for this image 

MHM