Previous post has already covered why segment routing is required with all it’s basic information. This post is mainly focusing on difference between SR Based MPLS Networks Vs Classic MPLS Networks.
Segment Routing Based MPLS Classic MPLS
MPLS Transport IGP IGP + LDP
IGP/LDP synchronization Not Required Required and Added More Latecny in Convergence
50msec FRR IGP IGP + RSVP-TE
Extra TE states to support FRR No extra state Extra states to manage
Optimum backup path Yes No
ECMP-capability for TE Inbuilt No
TE state only at headend Yes No (n^2 problem at midpoint)
Seamless Interworking with classic MPLS Yes NA
SDN Support Yes No
Routing Constraint Based (Source can Define) Destination Based + RSVP-TE
Link information (Bandwidth, IGP metric, TE metric, SRLG ) is flooded throughout the IGP domain No
Path Calculation CSPF or By Using Centralized Controller IGP + RSVP-TE
Scalability High Low
Operations and Troubleshooting Low High