Steven Bellovin wrote:
Considering that the reason to have multiple routers should be for redundancy, there is no point to use one of them as the default router.
VRRP? The Router Discovery Protocol (RFC 1256). But given how much more reliable routers are today than in 1984, I'm not convinced it's that necessary these days.
How much, do you think, more reliability required to the Internet today than in 1984?
There was a lot less understanding of the difference between hosts and routers in 1984 than there is today -- if nothing else, note how 4.2BSD and 4.3BSD considered all multihomed machines to be routers.
Unlike routers, multihomed machines without forwarding should listen IGP but must not advertise routes, which was well understood very well even at that time. It is the right thing to do, as is proven by the 99.8% argument that Microsoft don't do so. :-) Masataka Ohta