From owner-freebsd-net@FreeBSD.ORG Fri Mar 28 16:20:14 2014 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 15C6AE63 for ; Fri, 28 Mar 2014 16:20:14 +0000 (UTC) Received: from mail-vc0-x22d.google.com (mail-vc0-x22d.google.com [IPv6:2607:f8b0:400c:c03::22d]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id C9647F62 for ; Fri, 28 Mar 2014 16:20:13 +0000 (UTC) Received: by mail-vc0-f173.google.com with SMTP id il7so6153840vcb.32 for ; Fri, 28 Mar 2014 09:20:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:content-type:content-transfer-encoding; bh=kDxBOibfGVMlMBblLHe3QJGu7n6ttbeADWkAberAor0=; b=Rbad6Hw2VH7A/eqnrcepAviuYk0WsXLgmd6GZoxaACWcs617rEkF10xqQ61/4/123/ JPsHLmC+r+xJ7P9Dv9zXgOZXOAatOyx4KzCGdQk4DYjnVh2buQEItsg41zmQ/c48GP/2 gOOgJyJqjKiBMnNraPLHswLSd0dqSeJUB3Sr1+MCUDUmQaxXR54lhdlU3yS1ol2Yg4Sl X45VTFxOIlCu6zmwvA5OZYfW8S7+0E2ILsShGEZ0UVZNopaTBP1Jx0H6bk4LqGRkmk6/ uigzSqobikzq7uSB7/vMlvXyvdempxytdjEK/52NZ5yngtU/ZkDr8u5gg33/gvHOXUKZ Pmdg== MIME-Version: 1.0 X-Received: by 10.58.229.167 with SMTP id sr7mr7692752vec.7.1396023612917; Fri, 28 Mar 2014 09:20:12 -0700 (PDT) Sender: jinmei.tatuya@gmail.com Received: by 10.220.173.133 with HTTP; Fri, 28 Mar 2014 09:20:12 -0700 (PDT) In-Reply-To: <5334509B.8010706@sande.im> References: <5334509B.8010706@sande.im> Date: Fri, 28 Mar 2014 09:20:12 -0700 X-Google-Sender-Auth: Sa5Hs6xxRI9LZp0mdgZFpdYrdhw Message-ID: Subject: Re: ipv6 neighbor cache question From: =?ISO-2022-JP?B?GyRCP0BMQEMjOkgbKEI=?= To: Mikal Sande Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: FreeBSD Net X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 28 Mar 2014 16:20:14 -0000 At Thu, 27 Mar 2014 17:23:55 +0100, Mikal Sande wrote: > Is the IPv6 neighbor cache supposed to not inlcude incomplete entries? Wh= en my freebsd box resolves a previously unknown ipv6 address with ndp it do= es not add anything to the neighbor cache before it gets a reachability con= firmation. I have viewed the neighbor cache with ndp -a. > > The ipv6 addresses in question are local, so I am pretty sure that on-lin= k determination is not interfering. The same thing happens with both link-l= ocal and global addresses. > > When I ping an unused ipv6 address I do not find any corresponding incomp= lete entry in the neighbor cache afterwards. But, if I ping an unused ipv4 = address i do find an incomplete entry in the arp cache. I am curious as to = why this behavior occurs. Is it intentional? Is it by design? > > The reason for my curiosity is that I have not observed this behavior in = other OSes such as linux and openbsd. I suspect that's something specific to recent versions of FreeBSD. The very original kernel neighbor cache and ndp implementations of the KAME project should have behaved as you expected above and actually saw with OpenBSD. I don't know if the change was intentional or a kind of defect, though. Hopefully someone more familiar with recent updates in FreeBSD can clarify that. -- JINMEI, Tatuya