Date: Tue, 29 Mar 2011 22:19:26 +1030 From: "Daniel O'Connor" <doconnor@gsoft.com.au> To: ticso@cicely.de Cc: Sergey Kandaurov <pluknet@gmail.com>, freebsd-current Current <freebsd-current@freebsd.org> Subject: Re: ipv6 / rtadv problem Message-ID: <6C3B14AB-AB41-4705-84C2-EEFC38656EE9@gsoft.com.au> In-Reply-To: <20110329113414.GA33138@cicely7.cicely.de> References: <451C39DA-76B9-4767-9FFC-24F2A182E301@dons.net.au> <AANLkTinaELN40kvgDrjN0=iPT1KJNS=P2duFEk7jRS2W@mail.gmail.com> <0C27BDBF-1F22-4DFD-A1A5-48D0BD1618BC@gsoft.com.au> <71147117-D87B-4F36-9838-238E144BB51F@gsoft.com.au> <AANLkTimxY_xft=Rr-Wos=42c%2B7Pb3X2axv%2BizycgNN0U@mail.gmail.com> <D5F8A67A-53EC-4E4A-AD17-0AB1A9F47321@gsoft.com.au> <20110329113414.GA33138@cicely7.cicely.de>
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On 29/03/2011, at 22:04, Bernd Walter wrote: >> Grr.. I had to reinstall today because I forgot to create a swap = partition and now I can't reproduce the problem :( >=20 > NDP effectively replaces ARP for IPv6. > Like ARP it is also learning by received packets and not only by = direct > query and because of this problems might be unnoticed. >=20 > Unlike ARP NDP is using multicast - instead of sending the inquiry to > a broadcast address each address has a solicatated multicast address = where > the query goes to. > A NIC driver might have broken multicast support, I doub't that's a > problem for your em, but it is more likely that the bug is on the = other > host. > It also could be a problem with multicast aware switches - getting > multicast switiching right isn't an easy task and many implementations > are full of bugs. > If an NDP entry expires a host typically reasks using the unicast = address > and the last known MAC, so once everything seems to run an underlying > multicast problem can live unnoticed for a much longer time. > Currently my own LAN router has a NIC driver with broken multicast > support and nevertheless everything seems to work fine since months > now, but I know the bug is there and that it can bite me each day. >=20 > And unlike ARP NDP is ICMPv6 and not an individual protocol, some > people agressivlely filter ICMPv*, which can easily catch too much. > Especially since many people configuring filter lists are not aware > of those solicitated addresses. Thanks for the information. > My assumption is that the problem is with the other host or switch > network and you just never noticed this so far because this kind of > problem can easily hide for a very long time. Hmm, I have pretty stupid hardware, I am fairly sure none of my switches = understand multicast. If I see it again I will try and get some more information -- Daniel O'Connor software and network engineer for Genesis Software - http://www.gsoft.com.au "The nice thing about standards is that there are so many of them to choose from." -- Andrew Tanenbaum GPG Fingerprint - 5596 B766 97C0 0E94 4347 295E E593 DC20 7B3F CE8C
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