Hello Cameron
The quick answer is yes, that’s all you need. This then begs the question, how does it work without additional information?
Well, when you issue the ip sla responder
command, it causes the target device to simply reply to all incoming IP SLA packets by default, providing additional information to the sending device. All of the “intelligence” of the configuration exists within the IP SLA sending device.
Prior to any SLAs being sent, the sender will send a control message to the responder with any information it needs, thus ensuring that the responder has all the information it needs to respond correctly. Does that make sense?
For more info, take a look at this Cisco command reference:
https://www.cisco.com/c/en/us/td/docs/ios/ipsla/command/reference/sla_book/sla_02.html#wp1055041
I hope this has been helpful!
Laz