IGP cost calculation for next-hop-based dynamic tunnels

IGP cost calculation is supported for next-hop-based dynamic tunnels. In multihoming networks with next-hop-based GRE or UDP tunnel, rpd chooses the best path by calculating IGP metrics. However, in single-homed networks, rpd installs the tunnel composite next hop in the Packet Forwarding Engine without any IGP cost calculation. BGP preferred a path with the lowest router ID, which was not cost effective. When multiple PE devices advertise the same route, BGP did not take into account the IGP cost to those devices. This new feature allows BGP to choose an IGP path with the lowest metric and set up a tunnel to a PE device with the lowest cost. Note that in the absence of IGP connectivity, Junos OS does not install the advertised routes in the Packet Forwarding Engine or create a dynamic tunnel.