segment routing could be considered as the successor of rsvp based te, most of the features described for te could be done with sr too. the routers within the core signal the te attributes in isis or ospf as before, but you assign an additional prefix sid to their loopbacks. the routers will allocate an adjacency sid to all of it's neighbors, and will advertise the beginning of the sr label block too. from that point, you can calculate the label of any given pe by simply adding the base advertised by the next hop p to the prefix sid advertised by the target pe. with this, you can send labeled traffic to any given pe without involving any other protocols or consulting any other devices by adding the base of the nexthop and the prefix sid of the target. you can construct loosely specified paths by stacking these labels expressing the nodes that must be traversed. one specific subcase of this is when you put a single label to address the remote pe as an outer, transport label. stacking the adjacency sids gives you rsvp like explicit routing capabilities. the main advantage of using sr is that it have no state at the p routers. the dataplane can use mpls or extension header before the ip header. here are the captures for mpls, srv6.