+------------+      +------------+
            | IS-IS Link |      | OSPF Link  |
            +------------+      +------------+
                       |          |
                       v          v
                      +------------+
                      |  synthetic |
                      +------------+
                            |
                +-----------+-------------+
                |           |             |
                v           v             v
      +-------------+ +------------+ +-------------+
      | Interface 1 | | Phys. Link | | Interface 2 |
      +-------------+ +------------+ +-------------+