This Recommendation specifies a concrete realization of the functional architecture defined in [ITU-T Y.2111]@ including: the specification of the physical entities involved in resource control signalling; the interfaces across which signalling takes place; and the mapping between these entities and interfaces and the corresponding functional entities and reference points in [ITU-T Y.2111]. Appendix I provides a table illustrating the mapping between these interfaces and the protocol specifications which realize those interfaces. NOTE ?C [ITU-T Y.2111] (11/2008) is a Revision 1 of ITU-T Y.2111 (09/2006)@ which was the base for [b-ITU-T Q.3300].