SID stack
           {Y, X}              +--------------+
                               | Multi-domain |
    _ _ _ _ _ _ _ _ _ _ _ _ _ _|     PCE      |
   |                           +--------------+
   |                              ^
   |                              | Binding
   |           .-----.            | SID (X)     .-----.
   |          (       )           |            (       )
   V       .--(         )--.      |        .--(         )--.
+------+  (                 )  +-------+  (                 )  +-------+
|Access|_(  MPLS DC Network  )_|Gateway|_(    IP/MPLS WAN    )_|Gateway|
| Node | (  ==============>  ) |Node-1 | ( ================> ) |Node-2 |
+------+  (    SR-TE path   )  +-------+  (    SR-TE path   )  +-------+
           '--(         )--'    Node       '--(         )--'
               (       )        SID of         (       )
                '-----'         Node-1          '-----'
                                is Y            SIDs for SR-TE LSP:
                                                {A, B, C, D}