Heads up: impending IPv6 Test Day

[Daniel P. Berrange]

On Thu, Jun 02, 2011 at 04:40:10PM +0100, Richard W.M. Jones wrote:
> On Wed, Jun 01, 2011 at 08:22:25AM +0200, fkooman at tuxed.net wrote:
> > This [1] may be of some help as a high level overview of how to deploy
> > IPv6 on a LAN and various operating system IPv6 compatibilities.
> > Fedora is doing quite well! The document is not a configuration help,
> > but it might make it clear how everything fits together and brush you
> > up on your IPv6 :-)
> [...]
> > [1]  http://www.surfnet.nl/Documents/IPv6%20Deployment%20In%20Local%20Area%20Networks.pdf
> 
> This document is a good introduction, but it appears to assume that
> I've got an IPv6 router and internet connection.  I guess that's not
> going to apply to very many people.
> 
> Is there an easy way I can set up IPv6 and a handful of machines on my
> LAN for testing, without requiring any IPv6 internet connection or an
> IPv6 assigned prefix?
> 
> The Linux machines on my LAN appear to have acquired IPv6 addresses, eg:
> 
> $ ip addr show eth0
> 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN qlen 1000
>     link/ether 00:e0:81:74:02:28 brd ff:ff:ff:ff:ff:ff
>     inet 192.168.0.128/24 brd 192.168.0.255 scope global eth0
>     inet6 fe80::2e0:81ff:fe74:228/64 scope link 
>        valid_lft forever preferred_lft forever
> 
> but pinging them gives me strange errors:
> 
> $ ping6 fe80::2e0:81ff:fe74:228/64
> unknown host
> $ ping6 fe80::2e0:81ff:fe74:228
> connect: Invalid argument
> $ ping6 fe80::2e0:81ff:fe74
> connect: Invalid argument

Anything with an  fe80:: prefix is a link local address, which
is only unique within the scope of a single LAN segment. Thus
if you want to send traffic to such addresses, you need to specify
the NIC to send the traffic out from. The vast majority of apps
using sockets have no way to let you do this. The only thing that
commonly uses the link local addresses is IPv6 autoconfig, at
which point you get a real IPv6 address, which is globally unique
that real applications can use.

Daniel
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