Re: [apnic-talk] Help required: Unable to Ping Global Ipv6 address from different host

[Jeroen Massar <jeroen@unfix.org>]

On Wed, 2006-04-05 at 14:38 +0530, somashekar wrote:
[..]

> /etc/sysconfig/network-scripts/ifcfg-eth0
> DEVICE=eth0
> BOOTPROTO=dhcp
> ONBOOT=yes
> TYPE=Ethernet
> IPV6INIT=yes
> IPV6TO4INIT=yes
> DHCP6C=yes
> IPV6ADDR=fe80::208:74ff:fe2e:4154

You should never have to specify a link local address, it is
automatically generated from EUI-64.

[..]
> Using dibbler-0.4.1-linux.tar for DHCP Ipv6 server and client
> 
> I got the Global inet6 addr which is 2000::bd

You get 2000::bd/128, which is where the problem lies.
Next to that 2000::/bd is a valid global unicast address and is most
likely not assigned to you. If you want a test address range either use
the documentation prefix (2001:db8::/32) or better use "Unique Local
Unicast" as per RFC4193 (http://www.ietf.org/rfc/rfc4193.txt)

> [root@localhost ~]# ifconfig
[..]
>           inet6 addr: 2000::bd/128 Scope:Global

This is only 1 single IP address and it doesn't 'know' where the other
IP address is.

Make it 2001:db8::bd/64 and it will work as then the other address
(2001:db8::7f/64) is in the same prefix and then there is a route
between the two IP addresses.

Other way around is to do:
ip -6 ro add 2000::7f/128 dev eth0
on the 2000::bd/128 box, and:
ip -6 ro add 2000::bd/128 dev eth0
on the 2000::7f/128 box

But that is quite nasty. Use use /64's per link as it is supposed to be
used.

Greets,
 Jeroen

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