IPv6 routed setup

[Guus Sliepen]

On Mon, Jul 02, 2012 at 07:46:48PM +0200, Jan Lühr wrote:

> > #!/bin/sh
> > ip addr add 10.0.1.1/16 dev $INTERFACE
> > ip addr add 2001:470:780f:1::1/56 dev $INTERFACE
> > ip link set $INTERFACE up
[...]
> By that I'm not sure, whether running an non-/64-Bit network is going to cause any side-affects. 
> Is it possible to assign a /64 network on $INTERFACE when working in routed mode?
> 
> Eg  
> ip -6 addr add 2001:470:780f::1/64 dev $INTERFACE 
> ip -6 route add 2001:470:780f::1/56 dev $INTERFACE
> 
> Are there any pros and cons?

The command:

ip addr add 2001:470:780f:1::1/56 dev $INTERFACE

Is equivalent to:

ip addr add 2001:470:780f:1::1 dev $INTERFACE
ip route add 2001:470:780f:1::/56 dev $INTERFACE

The prefix (/56) has nothing to do with the address itself. If you are using
2001:470:780f:1::/64 on a LAN interface already, you certainly do not want to
do "ip addr add 2001:470:780f::1/64 dev $INTERFACE", because then you will have
two conflicting /64 routes, one to your LAN interface and one to the VPN
interface.

The exact same thing applies to the IPv4 configuration: you should add
10.0.1.1/16 to $INTERFACE, not 10.0.1.1/24.

-- 
Met vriendelijke groet / with kind regards,
     Guus Sliepen <guus at tinc-vpn.org>
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