Re: [arch-projects] [netctl][patch] Remove DAD detection

On Wed, Feb 6, 2013 at 11:48 PM, Sébastien Luttringer wrote:

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DAD detection is detected via the presence of tentative flag in ip command. This flag can only be setted if interface is up (obviously).

So, setting an IPv6 address will fail when you: - the cable is not plugged - any interface of a bridge is not set

The code was (before rewriting of netctl) reference this bug report: https://bugs.archlinux.org/task/28887

This bug will reopen after your proposed changes. I don't think so. The bug was about DAD no waiting enough time. This

If the cable is not plugged there is no point in trying to connect anyway Connect, but configure? Setting a IP address to an interface doesn't mean trying to connect to anything or having an internet connection. It just mean setting an ip. Port can be up or down, or change of states every minutes. We don't care. netctl should not fail to setup a static ip on iface when no

so it would be nice if you describe in some more detail what problem your changes solve. Imagine a router on archlinux, with a bridge of n ports. People can

On Thu, Feb 7, 2013 at 12:36 PM, Jouke Witteveen wrote: patch drop the DAD check logic by userland (same behaviour than ipv4). link is detected at boot. Sometimes, setting an IP on iface can be used to allow kernel to accept packet to this destination without really own it (lvs by example) plug (or not) their computers when they wants. Mostly, when you boot your router, noboby is plugged. When the router starts, it defines IPv4 and IPv6 on the bridge (where all ethernet ports are added). With the current netcfg/netctl, it's impossible because when nobody is plugged, DAD cannot do is job of checking ip address, because all the underlying interface can't send icmpv6 ND messages. I've tested to disable dad (sysctl accept_dad)[1] but interface stay in tentative mode and netctl timeout and rollback configuration.[2] Here I don't see why we *care* about DAD when setting ipv6 in _static_ mode. This is really usefull (and required) in stateless mode and was defined in ND RFC[3] for stateless autoconfig RFC[4]. If you really want check DAD, which is a completly correct behaviour in stateless, we maybe use dadfailed[5] instead of tentative[6] in our check. Cheers, [1] Not really surprising as parameter is about accept and not using DAD crafted ND. [2] There is currently no check in the netcfg code about activating or not the sysctl accept_dad. Should we add it as we do with accept_ra? [3] http://tools.ietf.org/html/rfc4861 look at §7 [4] http://tools.ietf.org/html/rfc4862 [5] http://git.kernel.org/?p=linux/kernel/git/shemminger/iproute2.git;a=commit;h... [6] http://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=blob;f=n... -- Sébastien "Seblu" Luttringer https://www.seblu.net GPG: 0x2072D77A