Date: Wed, 13 Mar 2013 18:12:36 +0100 From: Mark Martinec <Mark.Martinec+freebsd@ijs.si> To: freebsd-net@freebsd.org Subject: Re: ipv6 default router Operation not permitted Message-ID: <201303131812.36388.Mark.Martinec%2Bfreebsd@ijs.si> In-Reply-To: <20130313162700.GD18992@defiant.konundrum.org> References: <20130312225018.GA13589@defiant.konundrum.org> <201303131659.04074.Mark.Martinec%2Bfreebsd@ijs.si> <20130313162700.GD18992@defiant.konundrum.org>
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Schrodinger wrote: > What I am confused about is that without ACCEPT_RTADV on re0, FreeBSD > doesn't perform Neighbour Solicitation for the default gateway but with > ACCEPT_RTADV it does ..... Why ? This is Neighbour Solicitation and not > Router Solicitation.... > > I understand that FreeBSD doesn't consider the defaulte gateway to be > "on-link" so it does not perform ND for it but why does it perform ND > when ACCEPT_RTADV is set on re0 ? "Surely" ACCEPT_RTADV only affects > Router Advertisements / Solicitations and not ND. > > I have done packet captures and with ACCEPT_RTADV I see the initial > Neighbour Solicitation and the Neighbour Advertisement to and from my > default gateway. > > Without ACCEPT_RTADV - FreeBSD simply doesn't try to perform ND for the > address. This is where I am uncertain if this is expected or not. That is a good question and I'd be interested in an answer too. Perhaps FreeBSD is implementing a predecessor to RFC 4861, i.e. the now obsolete RFC 2461: RFC 4861, Appendix F: Changes from RFC 2461 o Removed the on-link assumption in Section 5.2 based on RFC 4943, "IPv6 Neighbor Discovery On-Link Assumption Considered Harmful". RFC 4943, Abstract This document describes the historical and background information behind the removal of the "on-link assumption" from the conceptual host sending algorithm defined in Neighbor Discovery for IP Version 6 (IPv6). According to the algorithm as originally described, when a host's default router list is empty, the host assumes that all destinations are on-link. Mark
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