Topology is as above. The firewall enables two OSPF processes. It enables process 1 with CMNET and enables process 2 with internal network. The process 2 learns CMNET default routing and it doesn’t force to issue the default routing. Two sets of firewall through process 2 learnt the cost of the default routing is less than the cost of the process 1. In testing we found the main firewall A doesn’t select the default routing issued by CMNET in process 2, but preferred select the default routing issued by the backup firewall which is learnt from process 1, causes the internet business flow round from firewall A to firewall B, leads to the business is interrupted.