I have cisco 1941 Router with IOS "c1900-universalk9-mz.SPA.150-1.M1.bin"
But it shows only..
Router(config)#ip sla ?
key-chain Use MD5 authentication for IP SLAs Control Messages
responder Enable IP SLAs Responder
Which IOS would be require for the feature?
No need to upgrade the IOS, the features are in the code. You need to buy the data license to active the feature. You can use the evaluation license to test the feature, but eventually you need the license to active the feature.