A set of companion documents describe an architecture for providing integrated services over low-bitrate links@ such as modem lines@ ISDN B-channels@ and sub-T1 links [1@ 2@ 3@ 4]. The main components of the architecture are: a set of real-time encapsulation formats for asynchronous and synchronous low-bitrate links@ a header compression architecture optimized for real-time flows@ elements of negotiation protocols used between routers (or between hosts and routers)@ and announcement protocols used by applications to allow this negotiation to take place. This document defines the service mappings of the IETF Integrated Services for low-bitrate links@ specifically the controlled load [5] and guaranteed [6] services. The approach takes the form of a set of guidelines and considerations for implementing these services@ along with evaluation criteria for elements providing these services.