Repair traffic is not always optimal when repair bandwidth is optimal.The former is relative to physical network topology.This paper aimed at reducing repair traffic based on routing codes.First

we modeled data transmission in physical networks based on information flow graph so that we could get the necessary and sufficient condition to feasibility of routing codes.And we found that routing codes could be realized based on regenerating codes.Then

we designed a protocol working on application layers to generate repair trees in Fat-tree

and a heuristic algorithm to generate repair trees in CamCube

which were both in agreement with their own design features of datacenter networks.Simulations about data-repair processes in systems using minimum-storage regenerating codes show that routing codes can reduce repair traffic efficiently

and performance of the two generation schemes of repair trees are both good in their own adapted networks.In fact

repair traffic had about 50% and 30% reductions in Fat-tree and CamCube respectively when the number of providers was small.