This feature implements RFC4861/RFC4862 router discovery.

I.e VPP is triggered through an API call to issue a Router Solicitation on a given interface (with timers, intervals etc etc). On receipt of a Router Advertisement message VPP will parse the message into a set of options. PIO, RDNSS in addition to router lifetime, flags and so on. VPP should not process any of the options, only pass the information up through the API to control plane clients who have registrered.

It is up to the control plane agent to install default route, assign addresses, use the learnt DNS recursive resolver information etc.

Open question: Who maintains the timers? E.g. when default route should expire. Control plane? VPP? Or FIB?