IPv6 Addressing and Subnetting

It’s easy to be a little intimidated when you come across an IPv6 address for the first time in its fully expanded form. First of all, at 128 bits in length, an IPv6 address is a full four times longer (in bits) than its IPv4 equivalent. Because of their length, IPv6 addresses are represented in hexadecimal rather than the common dotted decimal notation you are familiar with from IPv4. However, before you start worrying about endlessly typing (and calculating) hexadecimal characters on each and every host on your network, it’s worth noting that IPv6 includes a variety of methods to make address deployment easier for administrators, features that I’ll cover in the IPv6 operation section below.

Beyond handling addresses differently, IPv6 also changes the method by which a network is subnetted. If anything, this method is actually simpler than with IPv4, because an IPv6 address includes a section to define a subnet number directly within the address itself. Once you understand where that field is, determining the subnet to which a host belongs is as easy as just reading and matching the number listed.

In this section I’ll walk you through some of the basic of IPv6 addressing and subnetting, including how IPv6 addresses are formatted and represented, how subnets are determined, how the address space itself is allocated, and the different types of addresses and transmission methods that exist.

Author: Dan DiNicolo

Dan DiNicolo is a freelance author, consultant, trainer, and the managing editor of 2000Trainers.com. He is the author of the CCNA Study Guide found on this site, as well as many books including the PC Magazine titles Windows XP Security Solutions and Windows Vista Security Solutions. Click here to contact Dan.