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Re: IPv6 addresses really are scarce after all

2007-08-22 02:29:01
On 22-aug-2007, at 4:39, RJ Atkinson wrote:

In one's home network, which was and is the subject of this thread,
one ought not worry about backhoes taking out the cabling in the
attic.  Since the uplink to the ISP would have a router in any
event, the part that might need to be redundant (i.e. the uplink)
can easily be redundant. :-)

Then again, mistakes are made even easier than in a more professional setting. I have even created a loop between two ports in a switch and two ports on a wireless base station myself accidentally because I forgot the base station was in bridge mode and not NATing between its two ports.

Really? When I was in school we had 8 Sun diskless work stations per room hooked up to a 10 Mbps switch and when those puppies started to swap over the network, you could read a book by the collision light and have a chapter finished before your helloworld.c was compiled.

(hub, not switch)

Absolutely yes.

That school's network/workstations must have been misconfigured.
We had easily over 1000 UNIX workstations on the same big yellow
Ethernet back in the day, without the kinds of issues you describe.

It wasn't misconfigured. This was simply before the days of affordable fast ethernet or ethernet switches, so it was a big 10 Mbps ethernet which simply wasn't fast enough to accommodate all the NFS traffic for the diskless work stations. If the systems had had local storage and the network traffic had been telnet and mail, there wouldn't have been any trouble.

Third, DHCP is a well understood technology that is deployed
at millions of sites world-wide and generally works quite well.

Quick guess: you weren't at IETF-69.

One deployment having issues is VERY different from
most deployments having issues.

I'm not saying most deployments have problems. I'm saying DHCP isn't immune to problems. And when you have a problem with your DHCP, your network is pretty much dead in the water.

So one ought to be able to use DHCP to provision
IPv6 addresses (out of that overall block of ~2^^64 IPv6 addresses
mentioned above) using say 16 bits (bits 64-79) for IPv6 subnetting
and the remaining 48 bits for naming IPv6 interfaces.

This requires that all IPv6 nodes do DHCPv6 and there's a DHCPv6 server. You won't see those two requirements met very often in today's IPv6 deployments.

Most IPv6 workstations/laptops support DHCPv6 client at least.

Untrue. Maybe the latest BSD/Linux distros come with one, but that would be a recent development. Windows XP and MacOS X don't do DHCPv6.

DHCPv6-capable servers are not rare within the set of IPv6-capable
routers/systems.

Cisco routers do DHCPv6 but no address assignment. I haven't seen any other production-quality DHCPv6 implementations. (But the last time I looked was 2 years ago.)

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