Subject: (IPng 7128) Re: host vs router

From: Richard Draves <[email-masked]>
Date: Thu, 28 Jan 1999 10:48:01 -0800

> I just realized that this doesn't work in practise since the spec
> states that when a host receives an RA that it should treat the
> sender as being a router from the NUD perspective. (Section 
> 6.3.4 setting of
> IsRouter to TRUE.)

This is a good point... the IsRouter rules say senders of Router
Advertisements are implicitly assumed to be routers ie forwarding
interfaces, and senders of Router Solicitations are implicitly assumed to be
hosts ie non-forwarding interfaces. (I've never liked that part of the
IsRouter rules. :-)

I think it would be fairly simple to revise the spec to allow for
non-forwarding advertising interfaces. But it would be more complicated than
revising the spec to explicitly prohibit non-forwarding interfaces from
advertising.

So unless there's some good case for allowing non-forwarding interfaces to
advertise, it seems the spec should be clarified to disallow them and
section 6.2.5 should be revised.

A counter-argument would be that if an implementation did decide to allow
non-forwarding advertising interfaces, it would not introduce any real
interoperability problems. At least, I haven't noticed any yet with MSR IPv6
release 1.2, which does support such interfaces. :-)

Rich
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