[148015] in North American Network Operators' Group
Re: Misconceptions, was: IPv6 RA vs DHCPv6 - The chosen one?
daemon@ATHENA.MIT.EDU (Masataka Ohta)
Thu Dec 29 17:30:12 2011
Date: Fri, 30 Dec 2011 07:30:16 +0900
From: Masataka Ohta <mohta@necom830.hpcl.titech.ac.jp>
To: Valdis.Kletnieks@vt.edu
In-Reply-To: <44691.1325175089@turing-police.cc.vt.edu>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
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.
