[Dnsmasq-discuss] No IPv6 router advertisements for subnets other than /64?

Roy Marples roy at marples.name
Mon Sep 16 11:16:39 BST 2013


On 16/09/2013 10:44, Simon Kelley wrote:
> SLAAC works by generating addresses by composing the prefix and the
> so-called Interface Identifier.
> 
> RFC-4291 says: "For all unicast addresses, except those that start
> with the binary value 000, Interface IDs are required to be 64 bits
> long and to be constructed in Modified EUI-64 format."
> 
> and RFC-4862 says: "If the sum of the prefix length and interface
> identifier length does not equal 128 bits, the Prefix Information
> option MUST be ignored."
> 
> from which I deduce that the prefix length MUST be 64 when using SLAAC.

An advertised prefix does not mandate the use of SLAAC.

See a related discussion about DHCPv6 and prefix length here:
https://lists.isc.org/pipermail/dhcp-hackers/2013-September/002019.html

That has links elsewhere to use case's where the prefix is most 
definitely not /64.

Thanks

Roy



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