Internet Protocol Version 6 (IPv6), sometimes called the "next generation" IP protocol (IPng), is designed by the IETF to replace the current version Internet Protocol, IP Version 4 ("IPv4"), which is now more than twenty years old. Most of today's network uses IPv4 and it is beginning to have problems, for example, the growing shortage of IPv4 addresses.
IPv6 fixes manyshortages in IPv4, including the limited number of available IPv4 addresses. It also adds many improvements to IPv4 in areas. The key benefits of introducing IPv6 are:
- 340 undecillion IP addresses for the whole world network devices
- Plug and Play configuration with or without DHCP
- Better network bandwidth efficiency using multicast and anycast without broadcast
- Better QOS support for all types of applications
- Native information security framework for both data and control packets
- Enhanced mobility with fast handover, better route optimization and hierarchical mobility
The following table compares the key characters of IPv6 vs. IPv4:
| Subjects | IPv4 | IPv6 | IPv6 Advantages |
| Address Space | 4 Billion Addresses | 2^128 | 79 Octillion times the IPv4 address space |
| Configuration | Manual or use DHCP | Universal Plug and Play (UPnP) with or without DHCP | Lower Operation Expenses and reduce error |
| Broadcast / Multicast | Uses both | No broadcast and has different forms of multicast | Better bandwidth efficiency |
| Anycast support | Not part of the original protocol | Explicit support of anycast | Allows new applications in mobility, data center |
| Network Configuration | Mostly manual and labor intensive | Facilitate the re-numbering of hosts and routers | Lower operation expenses and facilitate migration |
| QoS support | ToS using DIFFServ | Flow classes and flow labels | More Granular control of QoS |
| Security | Uses IPsec for Data packet protection | IPsec becomes the key technology to protect data and control packets | Unified framework for security and more secure computing environment |
| Mobility | Uses Mobile IPv4 | Mobile IPv6 provides fast handover, better router optimization and hierarchical mobility | Better efficiency and scalability; Work with latest 3G mobile technologies and beyond. |
Few in the industry would argue with the principle that IPv6 represents a major leap forward for the Internet and the users. However, given the magnitude of a migration that affects so many millions of network devices, it is clear that there will be an extended period when IPv4 and IPv6 will coexist at many levels of the Internet
IETF protocol designers have expended a substantial amount of effort to ensure that hosts and routers can be upgraded to IPv6 in a graceful, incremental manner. Transition mechanisms have been engineered to allow network administrators a large amount of flexibility in how and when they upgrade hosts and intermediate nodes. Consequently, IPv6 can be deployed in hosts first, in routers first, or, alternatively, in a limited number of adjacent or remote hosts and routers. Another assumption made by IPv6 transition designers is the likelihood that many upgraded hosts and routers will need to retain downward compatibility with IPv4 devices for an extended time period. It was also assumed that upgraded devices should have the option of retaining their IPv4 addressing. To accomplish these goals, IPv6 transition relies on several special functions that have been built into the IPv6 standards work, including dual-stack hosts and routers and tunnelling IPv6 via IPv4.
IPv6 over IPv4 Tunnelling
Related Terms: IPv4, IPv6, Anycast, Multicast, Broadcast, Mobile IP, DHCP, QoS, ToS, IPsec, UPnP
Reference Links:
http://www.ipv6.org: All about IPv6
www.cs-ipv6.lancs.ac.uk/.../ papers/BayNetworks/: IPv6 White Paper