The key objective of this recommendation is to specify the end-to-end performance that could be achieved by an IP network when the backbone network providing the connectivity between the IP Routers is provided by Frame Relay infrastructure. This recommendation does not specify end to end performance objectives for IP networks. The Recommendation provides an estimate of the IP layer performance obtained when Public Frame Relay Data Networks are used to transport the IP packets and indicates how the IP QoS classes defined in Recommendation Y.1541 could besupported. The Recommendation provides an analysis of the Mappings between the Frame Relay and IP performance parameters. Numerical values of the expected IP performance parameters are derived from the objective values specified for the Frame Relay Performance parameters as specified in Recommendation X.146. Using a general model an analysis of the expected performance for various IP Packet sizes (corresponding to various IP applications) and the influence of the Frame Relay Network infrastructure (eg inter-node transmission trunks) is provided. This analysis provides an upper bound on the performance that could be achieved by an IP network when carried over a frame relay network, since the IP network infrastructure could increase both the achieved IP packet transit delay and IP packet loss rate. This recommendation, and in particular the performance parameter mappings between Frame Relay and IP Networks is seen as complementary to Recommendation Y1541, since Rec Y.1541 is technology independent with regard to the provision the physical and link layers The scope of the Recommendation is limited to IP networks where the link infrastructure is provided by or supported by Public Frame Relay Data Networks.