Date: Sun, 25 Apr 2021 17:56:01 +0000 From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: Zhenlei Huang <zlei.huang@gmail.com> Cc: "Rodney W. Grimes" <freebsd-rwg@gndrsh.dnsmgr.net>, freebsd-hackers@freebsd.org Subject: Re: Are there any RFCs for address selection for IPv4 Message-ID: <8834.1619373361@critter.freebsd.dk> In-Reply-To: <BF63DA36-A778-4207-B95C-353B0DE4D98C@gmail.com> References: <202104251340.13PDej0b093486@gndrsh.dnsmgr.net> <BF63DA36-A778-4207-B95C-353B0DE4D98C@gmail.com>
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-------- Zhenlei Huang writes: > Reading RFC 3927 2.7, it states link-local addresses are not routable. T= he router shall > discard those packets from or to link-local addresses. Then it make no s= ense for a host > to select link-local address as source address when it initialize a conn= ection, except for = > an edge case that the destination is also link-local address. As I understand it, it only makes sense let the kernel select a LL address= under two conditions: A) The destination is also LL *or* multicast B) There is only one "UP" interfaces with an LLA. Implementing the second criteria runs into us putting a (IPv6)LL on the loopback interface. Does anybody know why we put a (ipv6)LL on loopback interfaces ? -- = 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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