A statistically multiplexed interface protocol for packet switched data communications that uses fixed-length packets, i.e., cells, to transport data. Note 1: Cell relay transmission rates usually are between 56 kb/s and 1. 544 Mb/s, i.e., the data rate of a DS1 signal. Note 2: Cell relay protocols (a) have neither flow control nor error correction capability, (b) are information-content independent, and (c) correspond only to layers one and two of the ISO Open Systems Interconnection--Reference Model. Note 3: Cell relay systems enclose variable-length user packets in fixed-length packets, i.e., cells, that add addressing and verification information. Frame length is fixed in hardware, based on time delay and user packet-length considerations. One user data message may be segmented over many cells. Note 4: Cell relay is an implementation of fast packet technology that is used in (a) connection-oriented broadband integrated services digital networks (B-ISDN) and (b) connectionless IEEE 802. 6, switched multi-megabit data service (SMDS. ) Note 5: Cell relay is used for time-sensitive traffic such as voice and video.