__________________________________
             __(           IP Network             )__
          __(                                        )__
         (               --        --        --         )
    --------   --   --  |SR|  --  |SR|  --  |SR|  --   --------
   | Ingress| |IR| |IR| |  | |IR| |  | |IR| |  | |IR| | Egress|
-->| Router |===========|  |======|  |======|  |======| Router|-->
   |   SR   | |  | |  | |  | |  | |  | |  | |  | |  | |   SR  |
    --------   --   --  |  |  --  |  |  --  |  |  --   --------
         (__             --        --        --       __)
            (__                                    __)
               (__________________________________)

  Key:
    IR : IP-only Router
    SR : SR-MPLS-capable Router
    == : SR-MPLS-over-UDP Tunnel