Date: Tue, 22 Dec 1998 14:46:15 -0800 From: "Justin C. Walker" <justin@apple.com> To: Kurt Keller <Kurt@pinboard.com>, net@FreeBSD.ORG Cc: wes@softweyr.com, shigetoh@zip.com.au Subject: Re: IP aliases Message-ID: <19981222144615.I5684@apple.com> In-Reply-To: <3.0.5.16.19981222225958.44879f9a@pop.pbdhome.pinboard.com>; from Kurt Keller on Tue, Dec 22, 1998 at 10:59:58PM %2B0000 References: <3.0.5.16.19981221225911.439f4d8a@pop.pbdhome.pinboard.com> <367F469C.E57CD5C2@softweyr.com> <3.0.5.16.19981222225958.44879f9a@pop.pbdhome.pinboard.com>
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On Tue, Dec 22, 1998 at 10:59:58PM +0000, Kurt Keller wrote: > Thanks for your help. > > I actually had a look in rc.conf as well, but was sure the netmask of > 255.255.255.255 was wrong. Actually it does work fine that way. Still, > I can't imagine why the netmask on this virtual interface should have > all bits set. See http://www.cypher.net/~black/ipalias.html (linked from the tutorial page on the FreeBSD site). This doesn't really explain at a deep level why this netmask makes things work, but will give you a warm fuzzy feeling :-} > This would mean, that FreeBSD won't let me simulate subnets on one > adapter card. Even though physically such networks would not be > separated, the pure logical separation can be handy for testing routing > stuff. > For example something like > > 192.168.1.0/255.255.255.192 > 192.168.1.64/255.255.255.240 > 192.168.1.96/255.255.255.248 > 172.17.32.0/255.255.0.0 > > on one single adapter card can be very handy for simulations. Which > makes me wonder whether FreeBSD supports variable length subnet masks. If I understand what you're getting at, the funky netmask is only needed if you are adding an alias that is on the same subnet as an existing address assigned to the interface. This basically avoids the EEXISTS response, and adds a route for you. If you want to use the "real netmask", the 'ifconfig' actually succeeds, but you have to add the route by hand. For "new" subnets, use the correct netmask. At least, that's the way things work for our (Rhapsody) systems. Regards, Justin -- Justin C. Walker, Curmudgeon-At-Large * Institute for General Semantics | Manager, CoreOS Networking | Men are from Earth. Apple Computer, Inc. | Women are from Earth. 2 Infinite Loop | Deal with it. Cupertino, CA 95014 | *---------------------------------------*------------------------------------* To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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