Forwarding loop avoidance using ordered forwarding information base updates in wired networks

A link-state routing protocol is one of the two main classes of routing protocols used in packet-switched networks for computer communications. Examples of link-state routing protocols include OSPF and IS-IS. During topology changes the routers converge to update their routing table. Such changes can be of unpredictable changes or planned events. During such convergence transient loops can occur which should be avoided. In this paper we present a mechanism which is based on ordering of the updates of the forwarding table of the routers. The supported topology changes are link transitions from up to down, down to up and updates of link metrics. Finally we show by simulation that sub-second loop-free convergence is possible on a large Tier-1 ISP network.