Category: IPv6

Mike was wondering whether his ISP is giving him what he needs to start an IPv6 pilot within his enterprise network. He wrote:

So I got an IPv6 assignment with a /120 mask (basically our IPv4/24 network mapped to IPv6) and two smaller networks to use for links between our external router and the ISP.

Dear Mike’s ISP: where were you when the rest of the world was preparing to deploy IPv6? Did you read IPv6 Unicast Address Assignment Considerations (RFC 5375) or IPv6 Address Allocation and Assignment Policy from RIPE or your regional registry?

My DHCPv6+PPPoE post received a very comprehensive comment from Ole Troan (thank you!) in which he explains the context in which DHCPv6 was developed (a mechanism to give a static IPv6 prefix to a customer) and its intended usage (as the prefix is static, it should have a very long lifetime).

However, when you deploy DHCPv6 in some modern access networks (it’s not just PPPoE, Carrier Ethernet fares no better), you might experience subtle problems. Let’s start with a step-by-step description of how DHCPv6 works:

Every time someone throws me an IPv6 curveball, I’m surprised when I discover another huge can of worms (I guess I should have learned by now). This time it started pretty innocently with a seemingly simple PPPoE question:

What happens if an ISP decides to assign dynamic IPv6 subnets? With static assignment, the whole stuff is pretty straight-forward due to ND, RA & DHCPv6, but if dynamic addresses are used, what happens if the subnet changes - how will the change be propagated to the end-user devices? The whole thing is no problem today due to the usage of NAT / PAT...

LAN address allocation with changing DHCPv6 prefix is definitely a major problem, but didn’t seem insurmountable. After all, you can tweak RA timers on the LAN interface, so even though the prefix delegated through DHCPv6 would change, the LAN clients would pick up the change pretty quickly. WRONG ... at least if you use Cisco IOS.

During my last Building IPv6 Service Provider Core webinar I got a lot of questions about IPv6 over PPPoE (obviously we’re close to widespread IPv6 implementation; I never got PPPoE questions before). I wanted to test various scenarios in my IPv6 lab and thus enabled PPPoE on an Ethernet link between CE and PE routers.

This time I wanted to test multiple configurations in parallel ... no problem thanks versatile PPPoE implementation in Cisco.

The attendees of my Building IPv6 Service Provider Core webinar get several sets of complete router configurations for a six router lab that emulates a typical Service Provider network with a residential customer and an enterprise BGP customer. The configurations can be used on any hardware (real or otherwise) supporting recent Cisco IOS software, allowing you to test and modify the design scenarios discussed in the webinar.

IT World Canada has recently published an interesting “Disband the ITU's IPv6 Group, says expert” article. I can’t agree more with the title or the first message of the article: there is no reason for the IPv6 ITU group to exist. However, as my long-time readers know, that’s old news ... and the article is unfortunately so full of technical misinformation and myths and that I hardly know where to begin. Trying to be constructive, let’s start with the points I agree with.

IPv6 was designed to meet the operational needs that existed 20 years ago. Absolutely true. See my IPv6 myths for more details.

ITU-T has spun up two groups that are needlessly consuming international institutional resources. Absolutely in agreement (but still old news). I also deeply agree with all the subsequent remarks about ITU-T and needless politics (not to mention the dire need of most of ITU-T to find some reason to continue existing). That part of the article should become a required reading for any standardization body.

And now for (some of) the points I disagree with:

2019-09-01: Stumbled upon this old blog post and fixed the "IAB adoption of CLNP" part. Would love to know more about what was going on, but couldn't find any details apart from a few vague mentions.

We all know that IPv6 deployment is a chicken-and-egg problem: Service Providers are slow to adopt IPv6 because they can’t charge for it and the content providers don’t care because there are no IPv6 customers.

My good friend Jan Žorž got a great idea during the Google IPv6 Implementers Conference and finally managed to write it down: all we need is a slight search engine preference for sites reachable over IPv4 and IPv6. A small well-publicized tweak in Google’s scoring algorithm would push the content providers toward IPv6 and force web hosting companies to roll out IPv6 support immediately.

The CFO magazine has recently published a FUDful article “Trouble Looms for Company Websites” (read it to see what CFOs have to deal with). Obviously, some people think it’s a good idea to throw FUD at CFOs to get the budget to implement IPv6. Long term, it’s a losing strategy; your CFO will become immune to anything coming from the IT department and ignore the real warnings.

Yes, it's time to make your content reachable over IPv4 and IPv6, more so if you’re in the eyeballs business. Google knows that. So does Facebook. Twitter doesn’t seem to care. Maybe because they’re not selling ads?

Following my “Transition to IPv6” articles, Jessica Scarpati from SearchTelecom.com wrote a series of articles covering the telecom transition plans and the problems they’re experiencing with the vendors and content providers.

In the second article of the series, “Deploying IPv6? Demand responsiveness from vendors, content providers”, she’s quoting John Jason Brzozowski from Comcast, John Curran from ARIN, Matt Sewell from Global Crossing and myself. My key message: vote with your money and take your business elsewhere if the vendors don’t get their act together.

One of the biggest hurdles Internet Service Providers will face in the near future is access to legacy IPv4 content once we run out of globally routable IPv4 addresses. Although it’s easy to offer your content over IPv6 (assuming you have a properly designed network using load balancers from a company that understands the need for IPv6 in Data Center), a lot of the “long tail” content will remain reachable only over IPv4.