From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mika Liljeberg Subject: Re: 2.4.21+ - IPv6 over IPv4 tunneling b0rked Date: 11 Jul 2003 03:04:29 +0300 Sender: netdev-bounce@oss.sgi.com Message-ID: <1057881869.3588.10.camel@hades> References: <20030710154302.GE1722@zip.com.au> <1057854432.3588.2.camel@hades> <20030710233931.GG1722@zip.com.au> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: yoshfuji@linux-ipv6.org, linux-kernel@vger.kernel.org, netdev@oss.sgi.com, pekkas@netcore.fi Return-path: To: CaT In-Reply-To: <20030710233931.GG1722@zip.com.au> Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org On Fri, 2003-07-11 at 02:39, CaT wrote: > And having remembered /127 being mentioned as bad I changed the > interface config to a netmask of /64. Dropped it and brought it > up and it all works. > > There's something fundamental about ipv6 netmasks that I just don't > understand... Well, the thing is that prefix:: is a special anycast address that identifies a router on the link prefix::/n, where n is the prefix length. You had configured a 127-bit link prefix, meaning that you had only one valid unicast address (last bit == 1) in addition to the router anycast address (last bit == 0). Normally, IPv6 networks are supposed to use 64-bit on-link prefixes but the implementation can be written in such a way that other prefix lengths can be configured. Setting your tunnel prefix to /64 is certainly the right thing to do. MikaL