Valdis.Kletnieks@vt.edu wrote:
IGP snooping is not necessary if the host have only one next hop router.
You don't need an IGP either at that point, no matter what some paper from years ago tries to assert. :)
IGP is the way for routers advertise their existence, though, in this simplest case, an incomplete proxy of relying on a default router works correctly. Beyond that, if there are multiple routers, having a default router and relying on the default router for forwarding to other routers and/or supplying ICMP redirects stops working when the default router, the single point of failure, goes down, which is the incompleteness and/or incorrectness predicted by the paper of the end to end argument. 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. Developing more complicated IGP proxy makes the incompleteness and the incorrectness not disappear but more complicated. Masataka Ohta PS Note that the paper was written in 1984, where as RFC791 was written in 1981.