Date: Thu, 24 Aug 2006 21:29:43 -0400 From: Pat Lashley <patl+freebsd@volant.org> To: Chuck Swiger <cswiger@mac.com> Cc: freebsd-net@freebsd.org Subject: Re: Zeroconfig and Multicast DNS Message-ID: <961EF4A5A611779A598DE704@garrett.local> In-Reply-To: <22D92E8D-DE18-4883-8E77-5567AF63DFE0@mac.com> References: <20060823221835.GA28978@lor.one-eyed-alien.net> <23D2619F6BACE4E728178EE5@garrett.local> <44ED3BD1.3030206@shapeshifter.se> <AC5769F16F9730CABCCC4E61@garrett.local> <44EDA9A5.2050108@shapeshifter.se> <BE1059C6974AD43BC382E107@garrett.local> <44EDBDD0.4050000@shapeshifter.se> <7CC9AC69410B69EBD31122E4@garrett.local> <44EDDB8C.9090504@shapeshifter.se> <0EC404BA0CA363942D250766@garrett.local> <20060824182640.GA37561@lor.one-eyed-alien.net> <B69C016E0D5F0C26B40BE4C0@garrett.local> <22D92E8D-DE18-4883-8E77-5567AF63DFE0@mac.com>
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> > I think this all means that for a multi-homed host, we should not > > automatically add a route for the 169.254/16 network. Instead, we > > should just add specific /32s as discovered; and use ARP when we > > need to find a new 169.254.x.y -> MAC translation. > > MacOS X has the notion of interface priorities; from RFC-3927: > > Mac OS X ensures that the connected interface with the highest > priority is associated with the Link-Local subnet. Packets addressed > to a Link-Local address are never sent to the default gateway, if one > is present. Link-local addresses are always resolved on the local > segment. > > Mac OS X implements media sense where the hardware and driver support > it. When the network media indicates that it has been connected, the > autoconfiguration process begins again, and attempts to re-use the > previously assigned Link-Local address. When the network media > indicates that it has been disconnected, the system waits four > seconds before de-configuring the Link-Local address and subnet. If > the connection is restored before that time, the autoconfiguration > process begins again. If the connection is not restored before that > time, the system chooses another interface to autoconfigure. But OS X also only supports Zeroconf on one interface at a time. We Can Do Better. > > There still remains the possibility of multiple distinct hosts > > having the same LLA IP address on separate local links; each > > attached to a separate interface. In practice that situation should > > be sufficiently rare that we can afford to ignore it until someone > > comes up with some clever way to handle it. (Or we all move to IPv6 > > and it becomes moot.) > > See section 4 of RFC-3927. No, that covers merging two previously disjoint networks; I don't think that it is intended to handle the case of a multi-homed host that is connected to both of them while keeping them separate. -Pat
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