DHCPv6 and prefix length

Rudy Zijlstra rudy at grumpydevil.homelinux.org
Sun Aug 22 22:35:59 UTC 2010

Petr Morávek [Xificurk] wrote:
> Hello,
> I'm running dhclient from dhcp package version 4.1.1_p1 for IPv6
> configuration and I'm having trouble to get the right configuration - my
> ISP uses subnet with 117 prefix length, but dhclient
> has hardcoded value 64.
You have me curious. The way i understand the IPv6 standard, the prefix 
is 64. And a prefix of 117 is actually invalid and breaks the standard. 
The assumption in IPv6 is that the 64 bit second part is always local. 
See also how link local addresses are determined.

Waiting for comments from those more knowledgeable.



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