Patent ID: 9742670
Date: 2017-08-22
CPC Classifications: H04L

Claim:
1. A method, comprising: in a network using Enhanced Interior Gateway Routing Protocol (EIGRP) in determining forwarding information, a packet switching device sending an EIGRP proactive distance vector protocol request message requesting an identification of an alternative route for a destination that is an EIGRP non-eligible backup path, while the packet switching device currently having an EIGRP successor that is valid for reaching the destination through the network, with the EIGRP proactive distance vector protocol request message being an extension of EIGRP and including one or more values identifying the proactive nature of the EIGRP proactive distance vector protocol request message for the destination to identify to a receiving packet switching device: not to enter an EIGRP active state for the destination and to provide an EIGRP proactive distance vector protocol reply message specifying an EIGRP non-eligible backup path; in response to said sent proactive distance vector protocol request message, the packet switching device receiving the EIGRP proactive distance vector protocol reply message from a backup neighbor packet switching device identifying the backup neighbor packet switching device through which is a backup loop free path to the destination, with the backup neighbor packet switching device being different than a neighbor packet switching device associated with the EIGRP successor; and responsive to said receiving the EIGRP proactive distance vector protocol reply message, programming backup state in the packet switching device for using the backup neighbor packet switching device to reach the destination in response to the EIGRP successor no longer being valid for reaching the destination through the network.