IPv4 hosts typically need to know the IP address of one or more Domain Name System (DNS) servers so that they can use DNS protocol messages to ask a DNS server to resolve that name into an IPv4 address.

IPv4 hosts need to know several basic facts before they can succeed in simple tasks like opening a web browser to view a web page. The next sections of this chapter broaden the discussion of IPv6 to include additional types of IPv6 addresses, along with the protocols that control and manage several common functions for IPv6. Table 17-4 Example IPv6 Prefixes and Their Meaningsīy an enterprise engineer for each individual linkġWhile an RIR can assign a prefix to an ISP, an RIR can also assign a prefix to other Internet registries, which can subdivide and assign additional prefixes, until eventually an ISP and then its customers are assigned some unique prefix. The text scatters a couple of more specific terms, but for easier study, Table 17-4 summarizes the four key terms, with some reminders of what each means.

The process of global unicast IPv6 address assignment examines many different prefixes, with many different prefix lengths. Prefix Terminologyīefore wrapping up this topic, a few new terms need to be introduced. Then, for the design in Figure 17-6, you could choose the following four subnets:īy using global unicast IPv6 addresses, Internet routing can be very efficient and enterprises can have plenty of IP addresses and plenty of subnets, with no requirement for NAT functions to conserve the address space. For example, a /112 prefix length could be used, extending the /48 prefix by 64 bits (4 hex quartets). However, any number of subnet bits could be chosen, as long as the host field retained enough bits to number all hosts in a subnet. NOTE - The subnet numbers in the figure could be abbreviated slightly, removing the three leading 0s from the last shown quartets.įigure 17-6 just shows one option for subnetting the prefix assigned to Company1. Note that the figure shows the subnet fields and prefix lengths (64 in this case) in bold. Figure 17-6 takes the concept to the final conclusion, assigning the specific four subnets to be used inside Company1.

Convert mac address to ipv6 link local