Date: Mon, 26 Apr 2021 14:24:55 +0000 From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: "Rodney W. Grimes" <freebsd-rwg@gndrsh.dnsmgr.net> Cc: Zhenlei Huang <zlei.huang@gmail.com>, freebsd-hackers@freebsd.org Subject: Re: Are there any RFCs for address selection for IPv4 Message-ID: <76578.1619447095@critter.freebsd.dk> In-Reply-To: <202104261350.13QDoA0E097896@gndrsh.dnsmgr.net> References: <202104261350.13QDoA0E097896@gndrsh.dnsmgr.net>
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-------- Rodney W. Grimes writes: > > Does anybody know why we put a (ipv6)LL on loopback interfaces ? > > I believe someplace in the bowls of all the IPv6 specs this > is a requirement. I could not find it quickly though. I'm not seeing Linux doing it for instance ? > Question: Should we allow a route to have a next hop of a LL(ipv4)? > Reason: RFC3927 2.6.2: > The host MUST NOT send a packet with an IPv4 Link-Local destination > address to any router for forwarding. > > So, arguably, it is a violation to allow the default route to have > a LL next hop for ipv4. For that matter, it is a violation to allow > ANY ipv4 LL address to be the next hop in the routing table(s). You are reading that wrong. It is OK to have a LL as next-hop. It is not OK to send a packet with dst=LL to any next-hop. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.
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