Juniper is proud to be a Diamond Sponsor of MPLS+SDN+NFV World in Paris (8 - 11 March 2016). We have some great live demonstrations on our booth so, if you plan to be there, a couple of minutes reading this may help you plan your time wisely.
Loop Free Alternates (LFA) or IP Fast Reroute (FRR) crystallized some years ago with a basic specification in [RFC5286]as a noteworthy concept to provide standalone backup path calculations just based on route inequalities.
This post follows-up my previous article Granular BGP advertise-external for MPLS L3VPNs with the intention to tweak and illustrate the BGP add-path feature implementation in Junos OS for IPv4 unicast and IPv6 labeled-unicast (6PE) routes. BGP add-paths provide a more comprehensive path diversity approach than diverse paths or advertise-external and in my view, multiple applications can be based on Junos OS BGP add-path tactical deployment in default instance tables.
In some BGP multi-homed environments between networks, it is possible to achieve shorter convergence times by using certain features beyond traditional [RFC4271] BGP rules. One of these features is the so-called BGP advertise-external or best-external, so that Autonomous System Border Routers (ASBRs) also advertise the best externally received path, even though it may not result as the ultimate best path from the selection algorithm.