Whenever you talk to a new startup evaluating whether you’d consider including their products in your network, don’t forget to ask them a fundamental question: “does your product support IPv6?”

If they reply “Nobody has ever asked for it”, it’s time to turn around and run away.

There are a few reasons for this recommendation.

First, if none of their customers asked about imminent technology like IPv6, it means that their customers are not forward-looking bunch but people who believe technology problems can be solved with glitzy UIs, unicorn dust and magic (see also RFC 1925 section 2.11 and this famous quote misattributed to Einstein). Do you really want to be in that crowd?

I apologize for breaking the news to some overly innocent people, but there really is no magic and no Bandwidth Fairy.

There might be other excuses, usually along the lines of “we know all about IPv6, but it’s not high on our priority list because whatever,” in which case you might want to do a deep dive into the architecture of their solution to understand whether adding IPv6 support is a trivial task (because the architecture of the product supports multiple address families) or a total overhaul of the product (because the product architects and developers still live in single-protocol world).

Alain Fiocco who’s been working on IPv6 for decades made an interesting statement in a Packet Pushers podcast: if you include IPv6 in your product from day 1, it increases your development costs by less than 10%. If you have to reopen the hood and retrofit IPv6 into existing code, it costs way more.

Also, there’s no guarantee that a product you’ve decided to buy eventually gets IPv6 support regardless of what the vendor promised you when you were buying it, because the overhaul might be too expensive. Some well-known load balancing and DPI product immediately come to mind ;)

The only excuse I would accept is “our product works with IPv6, and we can demonstrate it, but we’re doing no testing on that part of the code”, because that shows that they do understand the multi-protocol nature of today’s Internet. However, even that is good enough only for products with software-only data plane. The moment forwarding hardware gets involved, you have to be way more careful.