HP 635n HP Jetdirect Print Servers - Practical IPv6 Deployment for Printing an - Page 15

mfp2.example.internal" would have failed because "ping mfp2.example.internal" effectively says: "only check the DNS server". Effectively in these last few configurations, although all the Vista machines and HP MFPs have an IPv6 address, communication only goes over IPv4. Can we force IPv6 to be used in these environments? Sure, but we are forced to use the IPv6 Link Local address explicitly, which really provides no benefit, is extremely error-prone, and can only be used for communication on the local subnet. As we can see, IPv6 for HP's printing and imaging devices results in "IPv6 Link Local Islands" because IPv6 is not used due to how name resolution operates. What IPv6 Address Range Should We Use? We've covered IPv6 being turned on by default and being deployed in IPv4 environments. What happens if we actually want to deploy IPv6 but do not want to have an Internet IPv6 presence? Rather than discuss a way of getting an IPv6 address range from an Internet Service Provider (ISP), this whitepaper will discuss the IPv6 Unique-Local range which can be setup for a given environment or "site". This process will not allow IPv6 address to be used to access the Internet directly, but will allow the deployment of routable IPv6 addresses in the intranet. We can use Unique-Local internally to a "site" and populate the internal DNS servers with this information (e.g. "example.internal" and not "example.com"). The Unique-Local Range is formatted as follows (from RFC 4193): Prefix: 7 bits Local Bit: a single bit set to a one. Effectively, the above shows the prefix for Unique-Local will be FD in hexadecimal Global ID: 40 bits or 5 octets Subnet ID: 16 bits or 2 octets Interface ID: 64 bits or 8 octets For our purposes, the 40 bits for the Global ID is the most important. What we want to do is come up a random way of generating the 40 bits. We only have to do this once for an entire site (Note: "site" is a loose term. A company may have several physical sites, but in this discussion all of those sites will have only one global ID and the different physical sites will be differentiated through the subnet field). We can simply borrow some dice from a family game at home or buy some from the store for a small amount of money. We will create a table of 40 rows. Each row represents a throw of a die. The value of the die throw will be converted to a binary value. This conversion is done as follows: If the die value is odd, the binary value is one; if the die value is even, the binary value is zero. An example table and values is shown in Figure 8: 15