An investigation of iterative routing algorithms

This paper presents a detailed analysis of an iterative routing algorithm in which multiple passes are made through a net list, varying the region of crossover on each net after every iteration. This is in contrast to conventional iterative routing algorithms which incorporate a crossover penalty within the cost function being minimised. Experimental results are presented and, based on these results, new modifications proposed. The modified algorithm is compared to a conventional iterative algorithm and a single pass Lee router. The results illustrate the improved completion rates of iterative algorithms with respect to single pass algorithms. Finally, an element of dynamic routing (ripup and reroute) is introduced to further improve the completion rate of the modified algorithm.