+------------------+
                         | Tunnel           |
                         | Service Instance |
                         +------------------+
                                   |
              +--------------------+-------------------+
              |                    |                   |
              v                    v                   v
         +-------------+    +--------------+    +-------------+
         | Peer1       |    | IP           |    | Peer2       |
         | Tunnel      |    | Connectivity |    | Tunnel      |
         | Interface   |    |              |    | Interface   |
         +-------------+    +--------------+    +-------------+
                |                  |                  |
                |    +-------------+--------------+   |
                |    |             |              |   |
                v    v             v              v   v
         +-------------+    +-------------+     +-------------+
         | Peer1       |    | IS-IS       |     | Peer2       |
         | Physical    |    | Routing     |     | Physical    |
         | Interface   |    | Protocol    |     | Interface   |
         +-------------+    +-------------+     +-------------+
                |                                     |
                v                                     v
         +-------------+                        +-------------+
         |             |                        |             |
         | Peer1       |                        | Peer2       |
         | Device      |                        | Device      |
         +-------------+                        +-------------+