Characteristic features of asynchronous transfer mode protocol are its virtual connections and the cell structure in data transfer.
One reason for the relatively small cells of 53 bytes is the minimisation of jitter when transmitting multiplex data streams. Large packets in a data transfer can therefore no longer block voice packets on a low-speed line. This minimises jitter of voice transmission.
ATM uses virtual connections which may be either temporary or permanent. The standard specifies virtual paths (VPs) and virtual channels (VCs) for this purpose. Packets with identical VPIs (Virtual Path Identifiers) and VCIs (Virtual Channel Identifiers) follow the same route through the network. Different virtual connections are also used to multiplex various services within the network.