[j-nsp] IPv6 subnetting

[Mark Kamichoff]

On Sun, Feb 03, 2008 at 05:58:26PM -0800, snort bsd wrote:
> So the statements above is what you refer to?
>
> The "subnet prefix" in an anycast address is the prefix that
> identifies a specific link. This anycast address is syntactically the
> same as a unicast address for an interface on the link with the
> interface identifier set to zero.

Yes.

> Then how does that calculate/126? It should give me four addresses
> with first one being network ID/anycast address and I could use rest
> of three, right? honestly, it doesn't sound right to me:
> 
> So, we subnet the address fec0::/126 according the rules of IPv4; 0~3,
> 4~7, 8~11, 12~15, and so on... fec0::14/126 is not the first address
> of that subnet.

You're thinking in decimal.  It's hex, and should go:

fec0::0/126: 0-3 (0 reserved)
fec0::4/126: 4-7 (4 reserved)
fec0::8/126: 8-b (8 reserved)
fec0::c/126: c-f (c reserved)

And, to keep going...

fec0::10/126
fec0::14/126 <--- (your example)
fec0::18/126
fec0::1c/126

So yes, fec0::14/126 is actually the first address.

- Mark

-- 
Mark Kamichoff
prox at prolixium.com
http://prolixium.com/
Rensselaer Polytechnic Institute, Class of 2004
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