IPv6 Netowrk Device Numbering BP

Thu Nov 1 11:11:17 UTC 2012

On Thu, Nov 1, 2012 at 7:31 AM, Crist J. Clark <pumpky at sonic.net> wrote:
> We're working out our dual stacked IPv4-IPv6 network. One
> issue that recently has arisen is how to number the management
> interfaces on the network devices themselves.
>
> I have always been kind of partial to the idea of taking advantage
> IPv6 features and letting hosts set their own addresses with EUI-64
> interface numbers. For the management interface on a network device,
> it's more like a "normal" host. I'd just as well tell the device its
> prefix, and let it build the address itself. For IPv6, my opinion is
> that I'm not even going to try to remember 128-bit addresses. It's
> not something reasonable to expect humans to do. I'm going to depend
> on some name-to-number service (DNS or a hosts file), and as far as
> a computer goes, 2001:db8::80:abff:fe45:6789 is just as easy to
> remember as, 2001:db8::12:34.
>
> The other approach is to assign addresses. To me, that's more of
> a hold over from IPv4 thinking, but there are legitimate reasons
> I can think of. It's nice to have the IPv6 address tied to the
> configuration rather than the hardware. If you need to drop in
> a replacement device, you copy the configuration and no addresses
> change. But OTOH, others might consider it a feature that the IP
> follows the device rather than the role. And the real reason I think
> people want to do it is that they want to be able to memorize IP
> addresses of "important" hosts like these.

For simplicity and a wish to keep a mapping to our IPv4 addresses,
each device (router/server/firewall) has a static IPv6 address that
has the same last digits as the IPv4 address, only the subnet is
changed.
You can say it's a IPv4 thinking model, but it's easier to remember
that if the fileserver it's at 192.168.10.10 then it's IPv6
counterpart address would be 2001:abcd::192:168:10:10 (each subnet
being a /64)

>
> Another option would be to do both. Assign a fixed address and also
> let it chose EUI-64. However, I see that leading to confusion. Not
> sure what good it would do.
>
> Is there anything like a standard, best practice for this (yet)?
> What are other people doing and their reasons? Anyone have operational
> experience with what works and what does not (and the "what does
> not" is probably really of more interest)?

Letting the host choose it's own IP can be very tricky and has
operational hurdles along the way as it's not that easy to copy
configurations across devices during upgrades and maintenance swap
outs.