> Dear IPv6-USers,
>
> (this is my first post here)
Hey, it's been quiet!
> Just wondering if the assembled wisdom on this list has any views about
> subnet numbering.
>
> I'm just at the very earliest stages of designing the IPv6 layout, and
> am trying to remember what I learnt on the 'test-run' of JANET/Tim
> Chown's IPv6 Fundamentals course some many months ago.
>
> We've got 2001:603:102::/48 assigned to us, and to start with I'm planning
> on carving it up in /64's more or less exactly inline with our existing
> IPv4 subnets.
>
> The numbering of the existing IPv4 subnets is well known and understood
> by the IT team here, so it makes sense to me to re-use it where
> possible. The question in my mind however is:-
>
> For a subnet 217 (for example), do I use:-
>
> 2001:630:102:217::/64
> or
> 2001:630:102:d9::/64
>
> Whilst the former is more 'readable' it's not really 'correct'.
>
> Thoughts?
> [snip]
> P.S. We also commonly use the subnet number as the VLAN number. The
> range for this (in Ethernet at least) is 12bits wide. This will fit in
> both decimal and hex into the 'subnet' word of the IPv6 address. So I
> don't think it has much bearing on the choice.
We also align VLAN numbers with IPv4 subnet numbers where we can (mainly
/24s within our /16 but we have schemes to match up parts of the private
space too). We've (almost) plumped for putting the BCD representation of
the VLAN number in the IPv6 subnet field - 4 digits, easily human
readable and plenty of space for expansion or other uses.
Sam
Sam Wilson
Network Team, IT Infrastructure
Information Services, The University of Edinburgh
Edinburgh, Scotland, UK
--
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.
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