This report describes progress during the second six months of a contract to make several improvements to ARPANET routing. A new line up/down protocol has been designed and implemented, and its performance has been extensively measured under actual network conditions. The protocol is described and the measurements are presented. Software routines to measure and report average packet delays on a per-hop basis have been designed and implemented. The routines are described, and measurements which have been performed using the routines are presented. A rigorous mathematical analysis of the stability of the SPF algorithm is presented. A protocol to ensure the rapid and reliable transmission of routing update message has been designed. It is described, and the reasons for choosing it are discussed. A preliminary design of enhanced message capabilities for the ARPANET (logical addressing, broadcast addressing, and group addressing) is presented. Finally, the interactions between routing and congestion control are discussed.