Subject: Re: [IPv6] PROBLEM? Network unreachable despite correct route

From: Bernhard Schmidt <[email-masked]>
Date: Thu, 11 Jan 2007 14:08:16 +0100

Jarek Poplawski wrote:

>> ip -6 route:
>> 2001:4ca0:0:f000::/64 dev eth0  proto kernel  metric 256  expires 86322sec mtu 1500 advmss 1440 fragtimeout 4294967295
>> fe80::/64 dev eth0  metric 256  expires 21225804sec mtu 1500 advmss 1440 fragtimeout 4294967295
>> ff00::/8 dev eth0  metric 256  expires 21225804sec mtu 1500 advmss 1440 fragtimeout 4294967295
>> default via fe80::2d0:4ff:fe12:2400 dev eth0  proto kernel  metric 1024  expires 1717sec mtu 1500 advmss 1440 fragtimeout 64
>> unreachable default dev lo  proto none  metric -1  error -101 fragtimeout 255
> Did you analyze this dev lo warning? 

That one is default. Recent kernels (since 2.6.12 or so, I think when 
the default on-link assumption was killed) have a default route pointing 
to "unreachable default lo" on bootup. Routes learned from RA or added 
statically are installed with a better metric and are preferred that way.

I think the use is to have a Network unreachable returned immediately if 
no IPv6 router is present.

Regards,
Bernhard