Date: Tue, 31 Jan 2006 00:19:11 +0300 From: Gleb Smirnoff <glebius@FreeBSD.org> To: Yar Tikhiy <yar@comp.chem.msu.su> Cc: freebsd-net@FreeBSD.org Subject: Re: Handling flags on vlan(4) Message-ID: <20060130211911.GG90131@FreeBSD.org> In-Reply-To: <20060130193937.GG72743@comp.chem.msu.su> References: <20060130193937.GG72743@comp.chem.msu.su>
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On Mon, Jan 30, 2006 at 10:39:38PM +0300, Yar Tikhiy wrote: Y> Presently our vlan(4) driver sets interface's flags to 0 initially Y> and copies a subset of them from the parent interface when the vlan Y> interface is attached to its parent. In particular, copied are flags Y> IFF_BROADCAST and IFF_MULTICAST. This approach has an unpleasant Y> consequence: if you assign IP to vlan before attaching the latter to Y> its parent, IP won't be properly set up on vlanX because the IP code Y> does some special things for IFF_BROADCAST and IFF_MULTICAST Y> interfaces; at least it sets up a broadcast address and joins the Y> all-hosts group. Y> Y> I can see two ways to deal with the problem. The ideal and hard Y> way is to provide hooks to notify upper network stack layers of Y> changes in interface properties. However, I doubt if such feature Y> is called for. The easy and practical way is to set IFF_BROADCAST Y> and IFF_MULTICAST on vlan from the beginning and prohibit vlan from Y> attaching to a non-bcast or non-mcast parent (which wouldn't work Y> anyway.) For now we can use the second way. I see no problems with it. -- Totus tuus, Glebius. GLEBIUS-RIPN GLEB-RIPE
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