On Thu, Nov 1, 2012 at 7:31 AM, Crist J. Clark <pumpky@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.