The problems of CBR(constant bit rate) traffic in ATM(Asynchronous Transfer Mode) networks are analyzed

and simple methods to calculate the cell loss ratio(CLR) and mean cell delay are derived.It is shown that on the one hand

even if a BW(bandwidth) equal to or larger than the Peak-Cell-Rate(PCR) is allocated for the CBR traffic

a large CLR may result in a small buffer system;on the other hand

with only a comparatively small buffer a very small CLR can be guaranteed when a large number of CBR sources are multiplexed.These results are important for the buffer design

BW allocation and connection admission control in ATM equipment.