[c-nsp] Faster BGP Failover

[Tim Franklin]

> in most cases we rather not change defaults (yes, I know, there have
> been too many cases where we did, incl. without notice)

Wonder of hindsight I know, but the recent bump of *3* major version numbers would have been a really good place to clean out a whole bunch of defaults that are no longer best-practice (or even sane).  "IOS 15 - now *fully* classless out of the box" would have been fantastic, but I understand this makes some Enterprise people cry ;)