Chapter 11. IPv6 and MPLS

IPv6 is the next version of IP. With a larger address space and more features, IPv6 is the direction in which many service providers are movingespecially in Japan and the Asian Pacific. With the rapid success of the Internet, every device connected to the Internet needs an IP address. Assigning public addresses to all devices is not an option because of the shortage of IPv4 addresses. Hence, the IPv4 addresses must be translated (network address translation [NAT]) using private address space to accommodate all the devices. IETF has standardized a new address family called IPv6 with 16 bytes or 128 bits of address space, a much larger address space than the 4 bytes or 32 bits of IPv4. In addition to addressing, IPv6 also provides improved security and data integrity, auto configuration, multicasting, and anycasting. (Anycasting is the ability of a sender to send traffic to the nearest device within the group. It provides integrated quality of service [QoS] as well efficiency in sending informationfor example, to update routing tables.)

The following is an extract of the IPv6 RFC 2460:

1. Introduction

IP version 6 (IPv6) is a new version of the Internet Protocol, designed as the successor to IP version 4 (IPv4) [RFC-791]. The changes from IPv4 to IPv6 fall primarily into the following categories:

• Expanded Addressing Capabilities

  IPv6 increases the IP address size from 32 bits to 128 bits to support more levels of addressing hierarchy, a much greater number of addressable nodes, and simpler auto-configuration of addresses. The scalability of multicast routing is improved by adding a "scope" field to multicast addresses. And a new type of address called an "anycast address" is defined, used to send a packet to any one of a group of nodes.

• Header Format Simplification

  Some IPv4 header fields have been dropped or made optional to reduce the common-case processing cost of packet handling and to limit the bandwidth cost of the IPv6 header.

• Improved Support for Extensions and Options

Changes in the way IP header options are encoded allows for more efficient forwarding, less stringent limits on the length of options, and greater flexibility for introducing new options in the future.

• Flow Labeling Capability

  A new capability is added to enable the labeling of packets belonging to particular traffic "flows" for which the sender requests special handling, such as nondefault quality of service or "real-time" service.

• Authentication and Privacy Capabilities

  Extensions to support authentication, data integrity, and (optional) data confidentiality are specified for IPv6.

As you notice, IPv6 is not just about expanded addressing capabilityit is much more. However, the primary driver for IPv6 has been and will be expanded address space. Due to a much larger address space, many carriers are considering allocating IPv6 addresses to mobile devices, such as cell phones. Several providers are actively evaluating IPv6-based services for mobile 3G/4G applications and mobile terminals. In fact, carriers in Japan have already begun this trend and are allocating IPv6 addresses to cell phones for 3G applications.

For carriers who plan to offer mobile services, IPv6 becomes an important protocol for delivering the next generation of services. IPv6 is also popular at universities for the Internet2 (next-generation Internet connecting universities) connections and 6bone (IPv6 backbone).

The options for service providers (SP) are simpleeither build an IPv6 backbone or build some translational or tunneling of IPv6 packets through IPv4 networks so that IPv6 edge services are available over an IPv4 network.