[c-nsp] Tracking state of non-directly connected link

[redscorpion69]

Hello,


What would be the best method of actively/passively keeping track of
validity of static route over GPON interfaces for example?

We want to give an option of backup floating static route over backup
interface, but need to be aware of primary link failure.

I could think of something like static bfd, which isn't available on all
platforms, or maybe GRE tunnel will keepalives?

Regards