The key objective of this Recommendation is to provide an estimate of the IP layer performance obtained in the case where Frame Relay network infrastructure is used to provide the lower layer connectivity to transport the IP packets between the routers. Mappings between Frame Relay and IP performance parameters are presented. Numerical values of IP performance parameters are estimated based on the objective values specified for the Frame Relay performance parameters specified in ITU-T Rec. X.146. A general model for the calculation of transfer delay is presented. This model can be used to assist in the planning of networks. The analysis presented provides an upper bound on the performance that could be achieved by an IP network when carried over a Frame Relay network. The performance mappings between FR and IP networks specified are seen as complementary to ITU-T Rec. Y.1541, since ITU-T Rec. Y.1541 is technology independent with regard to the provision of the physical and link layers. Accordingly, this Recommendation does not specify end-to-end performance objectives, but illustrates the way in which the Y.1541 objectives could be supported.