Thursday, April 25, 2013

IPv6 Subnet Calculator

We've just published a free online IPv6 subnet calculator for your use and enjoyment. For the uninitiated, a subnet is a subdivision or allocation of a larger address block. Subnetting is necessary to enable an organization to carve up the address block received from its ISP into subdivisions across the organization in order to provide IP address capacity to end devices requiring IP network access. In many enterprises, the subnetting process involves tiers or layers to better map to the organization's routing structure, security policies, applications' routing requirements, or other reasons. Thus in the simplest case, an organization choosing to use the private space, they may choose to allocate bits 9-16 to the top layer of its address hierarchy. This would yield 256 subnets, starting from,,, on up to Each /16 could in turn be further subdivided using bits 17-24 to create 256 subnets for each of the 256 /16 blocks. For example, within the block, the first such subnet is and the last is

In this trivial example, subnetting was quite easy because our subnet sizes coincided with our notation boundaries; that is the size of each subnet was 8 bits corresponding to the dot-separated decimal numbers. If you've worked with subnetting IPv4 blocks, you've probably encountered the more challenging task of subnetting on non-octet boundaries. Converting the 32-bit IPv4 block to binary, counting out to the subnet bit length, then back to dotted decimal is the sure-fire way to perform this function.

IPv6 introduces a much longer binary string with 128 bits, though the IPv6 addressing architecture specifications stipulate minimum subnet sizes of /64 (64 bits) in most cases. This leaves 64 bits to work with, which is twice as many as an entire IPv4 address in bit length. The other wrinkle of course is that IPv6 addresses are expressed in hexadecimal, which makes the conversion to binary and back more challenging or at least less familiar. To help you get your head around this process, we've published our IPv6 subnet calculator. It's even mobile-compatible so you can bring it up wherever you are.

Just enter your IPv6 block address (the default shown is the IPv6 documentation address), define the prefix length, then select the subnet size corresponding to the CIDR length of each subnet. Click the Calculate button and you'll see the resulting subnets displayed. Depending on the subnet size with respect to the prefix length, the results may span several pages. You can also select the page size to fit the device on which you happen to be using the calculator. Feel free to post a comment or send me an email with any feedback or comments!

Thursday, April 11, 2013

Learn about IPAM with our free webinar series!

As we have done several times over the years, we are planning another webinar series offering educational material regarding IPAM technologies including IPv6, DNSSEC and IDNA. The full webinar lineup, dates and times, and brief synopses are posted on the BT Diamond IP website. Register for any number of topics you're interested in.

When planning such a series, we certainly have no shortage of topic ideas. IPv6 as always remains of high interest from the Internet community at large. We ran an intensive 5-webinar IPv6 series about a year ago, and these webinars are still relevant and posted for playback on the BT Diamond IP website. So this time around, I selected three different IPv6 webinar topics. 

The first seeks to relate IPv6 to "managers," which yes as the title unfortunately implies, is somewhat "dumbed down" technically in terms of describing IPv6, but it also includes topics related to how IPv6 can impact one's business. I'll discuss the potential benefits of deploying IPv6 from potential cost savings and revenue upsides, to "softer" benefits as well. On the cost side of the equation, I'll discuss major cost areas to consider, though it is really up to each organization to define the scope and extent of their IPv6 deployment, so costs will be implementation-dependent.

Our second webinar will cover the IPv6 deployment process in general. This webinar will nearly coincide with the launch of our new IPv6 Deployment and Management book, which itself covers the topics to be discussed in this webinar. So think of this one as the "audio cliff notes" version of the book! Our third webinar will discuss IPv6 address planning in more depth. IP address planning is what we do and many of our customers have asked us for help in defining such a plan for IPv6. This webinar will provide guidelines and discuss trade-offs for various approaches.

The second half of our series shifts gears to other germane IPAM technologies, starting off with an "Introduction to IPAM" webinar. We at BT Diamond IP have been in the IPAM industry for nearly twenty years and we arguably founded the very IPAM industry itself. So we know a thing or two about IPAM; but the term IPAM has unfortunately been muddied over the last few years to camouflage the IPAM shortcomings of some highly visible DDI vendors. So this webinar seeks to set the record straight on what IPAM truly comprises. 

Our final two webinars address a pair of increasingly important DNS technologies, DNSSEC and IDNA. DNSSEC, like IPv6 has been around for over a decade. And while IPv6 deployments are starting to gain traction, DNSSEC deployment continues to languish. But let's face it, for DNS engineers, the topic of asymmetric key cryptography is a bit intimidating if not orthogonal to the DNS technology they understand inside and out. So we'll discuss the cryptography process at a basic level, discuss what DNSSEC does and doesn't protect, and talk about ongoing administrative duties and potential time savers.

Internationalized Domain Names (IDNs) are domain names represented in "native language" characters, i.e., non-Roman alphabets. DNS specifications dictate that DNS information be communicated "on the wire" as ASCII characters, which represent well the Roman alphabet. To enable broader unicode character sets, the IDN for Applications (IDNA) standards were codified within the IETF. IDNA enables a character string represented as unicode characters to be transformed into a string of ASCII characters, enabling the IDN to be represented in zone files and on the wire in ASCII per DNS specifications. So why is IDNA important? It enables organizations to present themselves to the Internet at large with native-language web addresses, email addresses, and so on. If your target market includes regions of the world that do not use strictly a Roman alphabet, then providing an Internet presence in native language could provide a marketing differentiator; and accessing your Internet presence starts with DNS.

I hope you find these topics of interest and the webinars useful. If you have any suggestions for other IPAM related topics, please feel free to post a comment below.

Wednesday, April 10, 2013

Book completed - now back to blogging!

It's been a few months since I've posted due to the urgency to finish my new IPv6 book, a death in the family and a period of abnormally onerous work requirements (always getting in the way!). My new book, co-authored with Michael Dooley is entitled, IPv6 Deployment and Management, ISBN-10: 1118387291/ISBN-13:978-1118387207, and will be available within the month.

Mike and I were motivated to write this book given the myriad questions we received from customers, prospects, and acquaintances about how to go about IPv6 deployment. Certainly having worked with IPv4 and IPv6 from an IPAM perspective for several years, we were able to share our experiences. However, there's much more to deploying IPv6 than managing the IPv4-IPv6 address space! So we set out to learn about the broader aspects of IPv6 deployment thanks to extensive research and interaction with some of our colleagues, and we discovered that it touches every aspect of the IP network. And given that I've never seen two identical IP networks, each one is unique, and the deployment planning and execution process likewise differs per IP network.

So there's no universal cookie cutter answer to the question of how to deploy IPv6, but we attempted to map out a basic process and identify key issues when planning an IPv6 deployment project. There's a lot to think about when implementing a new protocol, from assessing the ability of current infrastructure (routers, switches, servers, end user devices, databases, applications, etc.)  to support IPv6, to defining how such a dual protocol network is to be managed and supported, to creating security practices and policies and certainly documenting and tracking the IP address plan. From this assessment, plans can be made with respect to remediating non-IPv6 complaint components, mapping out a project plan, testing and executing the plan.

The book provides a detailed discussion of IPv6 deployment drivers, the IPv6 protocol, IPv4-IPv6 co-existence techniques, and key considerations when deploying IPv6 including IP addressing, network management and security. Readers may find that just particular sections apply to them, or all of them!