[FROG] Failed to start frr.service: Unit frr.service not found

Hi, I installed FRR on my Ubuntu virtual machine from source, hoping to use it with CORE for multicast routing with PIM. However, I haven't been able to manage even that; when I attempt to start the FRR service (sudo service frr start) I am given the error message in the subject (Failed to start frr.service: Unit frr.service not found.) This is despite me running the command in my /frr/tools directory where frr.service is located. Am I missing something here? Best regards, Ian Oakley