UP                       CP
                     | Synchronization Request |
                     |<------- via Ci----------|
                     |                         |
                     | Synchronization Begin   |
                     |-------- via Ci--------->|
                     |                         |
                     | Board/Interface Report  |
                     |-------- via Ci--------->|
                     |                         |
                     | Synchronization End     |
                     |-------- via Ci--------->|
                     |                         |
                    1) Synchronization from UP to CP

                     UP                       CP
                     | Synchronization Request |
                     |-------- via Ci--------->|
                     |                         |
                     | Synchronization Begin   |
                     |<-------- via Ci---------|
                     |                         |
                     |      Synchronizes       |
                     |Subscriber Session States|
                     |  Network Route Entries  |
                     |<------- via Ci----------|
                     |                         |
                     | Synchronization End     |
                     |<-------- via Ci---------|
                     |                         |
                    2) Synchronization from CP to UP