This paper proposes a new cross layer scheme (fast RSVP) to reserve resources for mobile IPv6. Through the cooperation of mobile IP and RSVP modules, fast RSVP includes a number of mechanisms such as advance resource reservation on neighbor tunnels, resource reservation on optimized routes, resource reservation for handover sessions (guard channel) etc. Network simulation results show that our scheme, compared with other traditional ways to reserve resources in mobile environments, has the following advantages: (1) it allows a mobile node to realize fast handover with QoS guarantees; (2) it avoids resource wasting caused by triangular routes and duplicate reservations; (3) it distinguishes different types of reservation requests, greatly reducing the handover session forced termination rate while maintaining high performance of the network.