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Let’s Demystify This IPv6 Thing

Is it Time to Convert Everything on Your Network?

Welcome to the future!

A great deal has been written about Internet Protocol Version 6. You’ve no doubt heard that we’re running out of IPv4 addresses (the familiar “” numbers) and that IPv6 is the answer. IPv6 also has many enhancements and improvements over the older v4.

But if you’re like me, maintaining one or more small-to-mid-sized IPv4 networks, you might wonder: What’s the bottom line? What do I need to do to get ready?

First, I disclaim: If you have a huge, continent-spanning network, what I say here may not apply to you. (Then again, you’ve probably got a full-time IT staff to worry about it for you.) I’ll gloss over a lot of detail too. My purpose here is not to explain the actual IPv6 specification; it’s to help you make an informed decision about how and when you begin your own upgrade. As usual, you should do a Web search for more information.

But if you want the quick, dirty bottom line, go stand at the Internet gateway for your building. For most of you, it’ll be the router/modem supplied by your ISP.

Look out onto the Internet and think, “IPv6 Land.”

Now turn around and look at your in-house network. Think, “MY land. I decide.”

Yep, it’s that simple. If everything in your facility is chugging along fine with IPv4, there’s no hurry. If you really wanted to, you could elect not to use TCP/IP at all. I’ll admit that’s not likely, but keep that in mind when an “IPv6 Consultant” calls and insists that you need to pay big money to convert everything right away.

I just angered some IPv6 fanbois by saying that, so I’ll compensate by covering some of IPv6’s advantages later.


There’s no way to predict the future. IPv6 proponents insist that it’ll be ubiquitous and worldwide within a few years at most. But there are many people — including yours truly — who wonder about that. Ironically, third-world nations may be the first to reach 100 percent on IPv6, because they’re still building their Internet infrastructure. They don’t have tons of existing IPv4 equipment that will need replacement.

Many of us do. Our stations have installed IPv4-only microwave data links for use as STLs. Our Wheatstone Generation 6 system is IPv4-only. We will not even consider upgrading these for some time. No doubt you can provide your own examples.

There are ways to make IPv4 and IPv6 coexist on the same network, but the folks who’ve actually done this warn that it isn’t perfect. You will have problems with it. For smaller networks, it’s probably not worth the expense, time and bother.

You need to have a serious talk with your Internet service provider about their IPv6 migration. If you host your websites elsewhere, talk to your hosting provider as well. If they’re rolling out IPv6 soon, you obviously need to ask them for an IPv6 address and the required dual DNS (i.e., both IPv4 and IPv6) entries right away.

But do have that serious talk. Yes, the last block of available IPv4 addresses was assigned in February 2011. When those numbers run out, it’ll either be IPv6 or (as I suspect) a hot market will develop for available IPv4 values!

For the record, I haven’t found a single ISP or hosting provider who requires IPv6 at present. There are still plenty of IPv4 numbers available here in Birmingham. Your mileage will vary and your city may be different.

There’s one other thing you need to consider (and talk about with your ISP). If you are given an IPv6-only Web presence and DNS entry, people who are on IPv4-networks may not be able to get to your website. For the record, I have talked to several ISPs about this and none of them was able to give me a satisfactory answer about how this will actually be handled during the transition.

The fact that so much of this is still up in the air alone should be enough to give us pause. Yes, IPv6 is coming … but let’s do this on our terms and according to our own timetable.

Broadcast equipment vendors give mixed responses on the subject of IPv6 as well. At the urging of our editor, I sent several requests for information: Where are you at? Are you planning to roll out IPv6 and if so, when?

I only got two responses, from Comrex and Tieline. They were markedly different.

Tieline has been IPv6-ready for some time now. If you get to a remote site with IPv6-only Internet access, you can plug and play. You’re ready to go.

The Tieline Genie codec is IPv6-enabled

Comrex, on the other hand, is where I suspect most vendors are. They’re ready at the hardware level, needing only a “flash” update or firmware upgrade to make it fly. Tom Harnett of Comrex provided this gem of a quote when I asked for further information:

“Comrex products all utilize software stacks that are fully IPv6-capable, and support will require some changes to the user interface firmware of our devices (e.g., to enable fields for longer static IP addresses). All our products are field-upgradable, so these user interface changes will be easy to apply when required. We actually haven’t released any IPv6-capable firmware to date for one reason — it hasn’t yet been requested by a single customer [emphasis mine]. We are readying major firmware releases including these changes this summer, and will have firmware ready on request for customers needing IPv6 compatibility before then.”


My “bottom line” rule is possible because of a very important distinction. The “shortage of IPv4 addresses” is primarily on the Internet.

Internet addressing is overseen globally by IANA, the Internet Assigned Numbers Authority. They decide which blocks of addresses will be used for which purposes. Some are assigned to each region, where a subordinate authority takes over. In North America, it’s ARIN: the American Registry for Internet Numbers. If you’re curious, the assignment data is online. For example, you can go to and enter any IP address to find out who “owns” it.

ARIN has granted to our ISP, Hiwaay Information Services, all IPv4 addresses from to Hiwaay, in turn, has leased to us for a mail server. We “own” this address; no one else can use it on the Internet.


Each host or device on any network must have a unique address (whether IPv4, IPv6 or something else entirely). Some years ago, when it became clear that IPv4 numbers would eventually run out, some workarounds were implemented as a stopgap measure.

IPv4 has 32-bit addresses, permitting 4.3 billion different values, from to Certain blocks are reserved for private networks; the familiar group from to is just one example. These addresses cannot be routed on the Internet. In fact, if a data packet makes it onto the Internet with one of these IP numbers as the source or destination, it’s called a “martian” and is slaughtered. Who says geeks don’t have a sense of humor?

Your network could have a printer at and mine could have a video camera at the same address. Since our networks are isolated from one another, we can both use the same block of numbers without a conflict.

Here’s the key. Since these networks are isolated, continuing to use IPv4 on a private network is going to work fine; the biggest thing is to ensure is that your connection to the Internet will work OK. Now, your ISP may assign your Internet connection an IPv6 number in the near future. But again, it’s your choice in-house. Don’t let anyone tell you otherwise.


Everyone focuses on the much larger IPv6 numbers, so let’s get that out of the way first. The addresses are 128 bits in size, allowing up to 340 undecillion(!) different address numbers. How’s that for killing a shortage?

IPv6 addresses are written as eight 16-bit blocks separated by colons, in hexadecimal (base 16, or “hex” if you’re a geek). One, and only one, string of consecutive zeros can be replaced by doubled colons. For example, all of these IP addresses might point to the same host:

(abbreviated, leading zeroes replaced with doubled colons) ::ffff:0:c0a8:01c8.

(By the way, this is just an illustration. Don’t just assume that you can use Windows’ Calculator program to convert “” to hex, add the “fe80:0:0:0:0:0” prefix and call it a day!)

The complete IPv6 specification has several other advantages. I’ll briefly mention a few.

First, IPv6 supports more efficient routing. The upper portion of the IP address is a “prefix” that tells an IPv6-aware router, on the fly, where to send the data. Rich, complex and layered routing schemes can be implemented easily with IPv6.

Second, it’s more secure. IPSec, or Internet Protocol Security, is mandatory and no longer optional as it was with IPv4. Everything on an IPv6 wire is encrypted and validated.

Third, you no longer need Network Address Translation (NAT). At present, the usual setup is for your IPv4 internal network to access the Internet with a router/modem that does this for you (see “The Mysteries of Network Masquerading,” RWEE, Aug. 31, 2010). Once everything is IPv6, NAT will no longer be required. Smaller facilities (and remember, that’s who I’m targeting here) would probably never notice the difference, but someone with hundreds of computers accessing the Internet might see a dramatic increase in performance.

Those network admins who’ve already converted to all-IPv6 claim that it’s actually easier once you get used to it, because of other advantages such as auto configuration. If you have a huge internal network, the security and efficiency alone might make it worth the expense.


Remember: think, “Internet, IPv6; but in-house, stick with what we’ve got.”

Now, when buying new equipment, you should opt for hardware that can do both IPv6 and IPv4. You may have to disable the IPv6 for now. But that way you’ll be ready (or readier, anyway) when you finally make your in-house transition to IPv6.

The key point that you need to take away from this is that there is no need to panic. For the Internet, yes, you should become familiar with IPv6. Talk to your ISP and hosting provider(s). For your internal networks, though, it’s up to you. IPv6 offers some real advantages over IPv4, but if you have a lot of IPv4-only equipment — as we do — you’ll probably decide just to “let it ride” for now.

And do read up on IPv6. I’ve only scratched the surface here. Good luck!

Stephen M. Poole, CBRE-AMD, CBNT, is market chief engineer at Crawford Broadcasting in Birmingham, Ala.