Next generation mobile networks (NGN) will be based on IPv6. Then, NGNs will require mobility protocols such as MIPv6 and HMIPv6. Also, they should support quality of service by means of technologies such as the integrated services architecture. In this context, a problem to distinguish reservations arises when resource reservations within tunnels are required. The current solution to this problem in the standard IntServ has some disadvantages such as reservations differentiation at the transport layer level. However, a new approach to support QoS over integrated services mobile networks has appeared. It is named IntServ6. This approach resolves the Reservations within Tunnels problem in a natural and simple way by means of the Flow Label field of the IPv6 packet header. Subsequently, it resolves this problem at the network layer level. This paper describes and evaluates such approach to support Reservations within Tunnels. Both QoS technologies, IntServ and IntServ6 are compared. Results show that IntServ6 serves more traffic than IntServ over Simple reservations and reservations within tunnels.