IP version 6
As you study this section, answer the following questions: * What is the primary reason for developing IPv6? * How many hexadecimal numbers are in an IPv6 address? How does this compare to a MAC address? * What do you add to an IPv6 address when you remove one or more quartets with all 0's? * What information is included within the IPv6 address prefix? * How many numbers are used for the interface ID? How can the interface ID be related to the MAC address? * What is the difference between ISATAP and 6-to-4 tunneling? * What is the difference between tunneling and NAT-PT?
This section covers the following exam objectives: * 1.3 Identify the following address formats * IPv6

IPv6 Facts
The current IP addressing standard, version 4, will eventually run out of unique addresses, so a new system is being developed. It is named IP version 6 or IPv6. The IPv6 address is a 128-bit binary number. A sample IPv6 IP address looks like: 35BC:FA77:4898:DAFC:200C:FBBC:A007:8973. The following list describes the features of an IPv6 address: * The address is made up of 32 hexadecimal numbers, organized into 8 quartets. * The quartets are separated by colons. * Each quartet is represented as a hexadecimal number between 0 and FFFF. Each quartet represents 16-bits of data (FFFF = 1111 1111 1111 1111). * Leading zeros can be omitted in each section. For example, the quartet 0284 could also be represented by 284. * Addresses with consecutive zeros can be expressed more concisely by substituting a double-colon for the group of zeros. For example: * FEC0:0:0:0:78CD:1283:F398:23AB * FEC0::78CD:1283:F398:23AB (concise form) * If an address has more than one consecutive location where one or more quartets are all zeros, only one location can be abbreviated. For example, FEC2:0:0:0:78CA:0:0:23AB could be abbreviated as: * FEC2::78CA:0:0:23AB or * FEC2:0:0:0:78CA::23AB
But not FEC2::78CA::23AB * The 128-bit address contains two parts: Component | Description | Prefix | The first 64-bits is known as the prefix. * The 64-bit prefix can be divided into various parts, with each part having a specific meaning. Parts in the prefix can identify the geographic region, the ISP, the network, and the subnet. * The prefix length identifies the number of bits in the relevant portion of the prefix. To indicate the prefix length, add a slash (/) followed by the prefix length number. Full quartets with trailing 0's in the prefix address can be omitted (for example 2001:0DB8:4898:DAFC::/64). * Because addresses are allocated based on physical location, the prefix generally identifies the location of the host. The 64-bit prefix is often referred to as the global routing prefix. | Interface ID | The last 64-bits is the interface ID. This is the unique address assigned to an interface. * Addresses are assigned to interfaces (network connections), not to the host. Technically, the interface ID is not a host address. * In most cases, individual interface IDs are not assigned by ISPs, but are rather generated automatically or managed by site administrators. * Interface IDs must be unique within a subnet, but can be the same if the interface is on different subnets. * On Ethernet networks, the interface ID can be automatically derived from the MAC address. Using the automatic host ID simplifies administration. |
IPv6 adds the following features which are not included in IPv4: Feature | Description | Auto-configuration | Because hardware IDs are used for node IDs, IPv6 nodes simply need to discover their network ID. This can be done by communicating with a router. | Built-in Quality of Service | Built-in support for bandwidth reservations which make guaranteed data transfer rates possible. (Quality of service features are available as add-ons within an IPv4 environment, but are not part of the native protocol.) | Built-in Security Features | IPv6 has built-in support for security protocols such as IPSec. (IPSec security features are available as add-ons within an IPv4 environment.) | Source Intelligent Routing | IPv6 nodes have the option to include addresses that determine part or all of the route a packet will take through the network. |
Although not yet widely adopted, you can implement IPv6 if your systems support it. As implementation of IPv6 proceeds, there will be cases when compatibility with IPv4 is required. Three strategies are recommended by IETF for IPv6 to IPv4 compatibility configuration: Strategy | Description | Dual Stack | With a dual stack configuration, both the IPv4 and IPv6 protocol stacks run concurrently on a host. IPv4 is used to communicate with IPv4 hosts, and IPv6 is used to communicate with IPv6 hosts. When implemented on hosts, intermediate routers and switches must also run both protocol stacks. Use a dual stack configuration to enable a host to communicate with both IPv4 and IPv6 hosts. | Tunneling | Tunneling wraps an IPv6 packet within an IPv4 packet, allowing IPv6 hosts or sites to communicate over the existing IPv4 infrastructure. With tunneling, a device encapsulates IPv6 packets in IPv4 packets for transmission across an IPv4 network, and then the packets are de-encapsulated to their original IPv6 packets by another device at the other end. Tunneling solutions include: * Intra-site Automatic Tunnel Addressing Protocol (ISATAP) for implementations within a site * 6-to-4 tunneling for implementations across sites * Teredo for tunneling between two hosts Use tunneling to allow an IPv6 host to communicate with another IPv6 host through an IPv4 network. | Network Address Translation-Protocol Translation (NAT-PT) | NAT-PT is a protocol that converts the IPv6 packet header into an IPv4 packet header, and vice versa. This method is different than tunneling because the packet headers are converted between the IPv4 and IPv6, whereas tunneling wraps the IPv6 packet into an IPv4 packet. Use NAT-PT to allow IPv4 hosts to communicate with IPv6 hosts. |