Dual stack IPv6 for IPv4 depletion

Thu Jul 9 16:16:32 UTC 2015

When I see a car that needs a /56 subnet then I’ll take your use case seriously. Otherwise, it’s just plain laughable. Yes, I could theorize a use case for this, but then I could theorize that someday everyone will get to work using jetpacks.

We have prefix delegation already via DHCP-PD, but some in the IPv6 world don’t even want to support DHCP, how does SLAAC do prefix delegation, or am I missing something else? I assume each car is going to be running as  RA? Given quality of implementations of IPv6 in embedded devices so far, I found that pretty ludicrous.

Seriously, the IPv6 world needs to get a clue. Creating new protocols and solutions at this point in the game is only making it more difficult for IPv6 deployment, not less. IPv6 needs to stabilize and get going.. instead it seems everyone is musing about theoretical world where users need 64k networks. I understand the idea of not wanting to not think things through, but IPv6 is how many years old, and we are still arguing about these things? Don’t let the prefect be the enemy of the good.

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Matthew Huff             | 1 Manhattanville Rd
Director of Operations   | Purchase, NY 10577
OTA Management LLC       | Phone: 914-460-4039
aim: matthewbhuff        | Fax:   914-694-5669

From: Harald Koch [mailto:chk at pobox.com]
Sent: Thursday, July 9, 2015 12:01 PM
To: Matthew Huff
Cc: Marco Teixeira; NANOG list
Subject: Re: Dual stack IPv6 for IPv4 depletion

On 9 July 2015 at 11:42, Matthew Huff <mhuff at ox.com<mailto:mhuff at ox.com>> wrote:
What am I missing? Is it just the splitting on the sextet boundary that is an issue, or do people think people really need 64k subnets per household?

One thing you're missing is that some of these new-fangled uses for IP networking will want to do their own subnetting. It's not "here's a subnet for the car", it's "here's a /56 for the car to break into smaller pieces as required".

A /56 isn't 256 subnets, it's 8 levels of subnetting (or 2 levels, if you're human and want to subnet at nibble boundaries). A /48 is 16 (or 4) levels. I have four vehicles, so I'd want to carve out a /52 for "the car network" to make the routing and security easier to manage, and leave room for expansion (or for my guests...)

One more consideration for you: we're currently allocating all IPv6 addresses out of 2000::/3. That's 1/8th of the space available. If we discover we've messed up with this sparse address allocation idea, we have 7/8ths of the remaining space left to do something different.

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Harald