Acceptable prefix sizes for Windows Vista/7

[Jack Bates]

Yeah, that was screwed up in wide-dhcp in linux too. You had to specify 
the number of bits for it to determine how to divide up the delegation 
for assignment, otherwise it divided it equally between all interfaces. 
The problem is, you don't know the prefix ahead of time. It's backwards 
logic. They should have supported specifying the final size (which 
normally would be /64) and then calculated the bit difference themselves.


Jack (wonder if netgear used wide-dhcp)

On 2/15/2011 11:51 PM, Frank Bulk wrote:
> Thanks.  Sounds like Netgear has to fix that, then.  They've already been informed.  They probably only ever tested with PDs of /64.
>
> Frank
>
> -----Original Message-----
> From: Erik Kline [mailto:ek at google.com]
> Sent: Tuesday, February 15, 2011 11:27 PM
> To: frnkblk at iname.com
> Cc: ipv6-ops at lists.cluenet.de
> Subject: Re: Acceptable prefix sizes for Windows Vista/7
>
>> Does Windows possibly have a requirement that the advertised prefix only be a /64 in order for SLAAC to work?
> I would think that this would be the expected behaviour actually.  I
> would be surprised if other operating systems didn't behave similarly
> for Ethernet interfaces.
>
> I see that http://tools.ietf.org/html/rfc4862#section-5.5.3 says you
> can do math (128 -n), but it looks like this paragraph may be trumping
> things, since EUI-64s are, well, 64bits:
>
>      If the sum of the prefix length and interface identifier length
> does not equal 128 bits, the Prefix Information option MUST be
> ignored.
>