From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Bieringer Subject: Re: [RFC IPv6] Disabling IPv6 autoconf Date: Tue, 29 Aug 2006 13:13:58 +0200 Message-ID: <44F42176.1000701@bieringer.de> References: <20060829082435.GA2676@suse.de> <20060829.183426.52410264.yoshfuji@linux-ipv6.org> <20060829.025400.37356422.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: David Miller , yoshfuji@linux-ipv6.org, okir@suse.de, netdev@vger.kernel.org, jbeulich@suse.de Return-path: Received: from smtp4.aerasec.de ([212.18.21.179]:6858 "EHLO smtp4.aerasec.de") by vger.kernel.org with ESMTP id S932306AbWH2LOK (ORCPT ); Tue, 29 Aug 2006 07:14:10 -0400 To: Pekka Savola In-Reply-To: Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Pekka Savola schrieb: > On Tue, 29 Aug 2006, David Miller wrote: >> From: YOSHIFUJI Hideaki >> Date: Tue, 29 Aug 2006 18:34:26 +0900 (JST) >> >>> Further analysis is needed, but one idea is to skip >>> addrconf_dev_config() if !(dev->flags & IFF_MULTICAST). >> >> Yes, it is logical because without multicast IPV6 cannot >> work correctly. >> >> But from another perspective (I assume these bridged Xen devices use >> ARPHRD_ETHER, do they?) a device with ARPHRD_ETHER and cleared >> IFF_MULTICAST flag seems potentially problematic. How many other >> things break over such a device? > > It's not obvious that IFF_MULTICAST is good enough. IMHO, you should be > able to run addrconf on non-multicast interfaces as well (e.g., > point-to-point interfaces, tunnels in particular). Hmm, at least on RHEL4 (2.6.9): 1: lo: mtu 16436 qdisc noqueue 2: eth0: mtu 1500 qdisc pfifo_fast qlen 1000 3: eth1: mtu 1500 qdisc pfifo_fast qlen 1000 4: sit0: mtu 1480 qdisc noop 5: sit1@NONE: mtu 1480 qdisc noqueue 6: ppp0: mtu 1492 qdisc pfifo_fast qlen 3 8: tun6to4@NONE: mtu 1480 qdisc noqueue And contributed from FC5: 5: vmnet8: mtu 1500 qdisc pfifo_fast qlen 1000 7: tun0: mtu 1500 qdisc pfifo_fast qlen 100 ppp0, tun0 has IFF_MULTICAST set, so not an issue. > It seems that current code already excludes IFF_NOARP interfaces though. So 6-in-4 tunnels are already except. Don't wonder about Flag "10000", missing support in "ip", already reported https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=202199 and fixed in rawhide. Just my 2 cents, Peter -- Dr. Peter Bieringer http://www.bieringer.de/pb/ GPG/PGP Key 0x958F422D mailto:pb@bieringer.de Deep Space 6 Co-Founder and Core Member http://www.deepspace6.net/ OpenBC http://www.openbc.com/hp/Peter_Bieringer/ Personal invitation to OpenBC http://www.openbc.com/go/invita/3889