Service function chaining technologies in service provider networks

Hi folks, I am wondering if service provider networks are actively implementing service function chaining, and if so, what kinds of technologies they are using in the network to steer traffic to services. Segment routing was suggested to me as an option that could work, and it seems like a good fit; however, I have no clue how widely deployed it is specifically for service function chaining. At this point I'd just like to understand what some of the common deployment models are from anyone who is willing to share. Thanks, -- Tim Upthegrove