End-to-end error recovery in ISDNs employing LAPD protocol on bearer channels

A comparison between two possible implementations, edge- and mixed-terminated, of LAPD protocol, to be used on the bearer channels of ISDNs, is presented. Mixed-terminated LAPD is characterized by terminating the protocol at the edge nodes and allocating to the transit nodes a subset of functionalities. The comparison shows that edge-terminated LAPD is superior to mixed-terminated under various load and control conditions. A potential for mixed-terminated LAPD to substantially increase its performance is identified depending on efficient implementation of specific functionalities