IP version 6 an Introduction
Due to the recent explosion in growth the Internet is running out of IP address space. Solutions to this problem have already been developed, such as Network Address Translation (NAT.) The problem with solutions such as NAT is that they do not scale very well. On the small scale they work well and have few problems if used with well known layer 4 services. But relying on port/address translation on a large scale is not a good idea. Therefore, your friends at places such as the IETF and Networking companies have come up with IPv6. IPv6 is similar to IPv4 in only basic coneptual design. The idea of splitting an address up into network and host portions is maintained. A masking is configured on the host so that it can determine if the layer 2 frame is locally destined, or if it should be sent to a gateway for processing.
As in IPv4, devices may share a single address, as long as they masquerade as the same device. This is useful for such techniques as server load balancing.
IPv6 addresses will be 128 bits in length, as opposed to 32 bits for IPv4 addresses. The new addresses will be expressed in hexadecimal format, as opposed to decimal, which IPv4 uses. Therefore, an IPv6 address will have the format:
FEDC:BA98:7B54:3210:F7DC:BA78:7654:A456
As you can see, the address notation is split up into 8 16 bit sections. Note that if there are leading zeros in any 16 bit section of the address, they may be omitted since they are not significant digits. Trailing zeros MUST be noted, however.
Legacy IPv4 addresses may be embedded into IPv6 addresses to allow for compatibility while migration is taking place. In these instances the last 32 bits of the IPv6 address will contain the embedded IPv4 address.
In addition to the basic addressing scheme, a new feature called a flowlabel will be added to the IPv6 header. This is a unique 24 bit identifier that represents a particular long lasting session between two hosts. This allows a router to more quickly identify what the proper path to a given destination is. Flowlabeling is useful for real-time technologies such as video and audio.
Security will also be available in IPv6. Building encryption into the 3rd layer makes it available to all services. Currently, encryption is implemented at the session layer or higher. Building it into the third layer allows any application using IP to take advantage of a secure connection.
