IPv6 address a lot concerns and issues that are faced today in using IPv4. Cisco CCNA Certification requires that a candidate must have a general overview of IPv6 and what new features it brings into the world of networking. Here we will go through some of the features of Internet Protocol Version 6 (IPv6).

The main feature of IPv6 are described in the sections below

Larger Address Space

IPv6 addresses are 128-bits long which gives us a theoretical address space of 3.4 x 10³⁸ addresses, like IPv4 some address space is reserved for special purpose but still there is a huge number of public routable addresses.

Aggregation

A larger address space allows for large address allocations to ISPs and Organization. This allows them to use a single prefix for the entire network making summarization easy and flexible which turn promotes efficient and scalable routing.

New Improved Header Format

Optional and non-essential fields are removed from the IPv6 Header and are moved the Extension Header that is placed after the IPv6 Header. Fewer fields of fixed lengths mean Header overhead is minimized and processing performance is improved.  Another significant enhancement is that all routers in a path do need to do checksum recalculation for an IPv6 Packet instead error detection is handled by data-link layer technologies checksums of the end-to-end connection at transport layer.

Figure 1 shows an IPv6 Header followed by Extension Header.

Allocation

IPv6 addresses are composed of two parts, 64-bit Network Prefix and 64-bit host part. The IPv6 address allocation follows a generally acceptable assignment policy as shown in figure 1. This allows for an efficient, hierarchical, and summarizable routing infrastructure.

Easy Address Assignment Methods

IPv6 has three assignment methods

• Static

• DHCPv6 (Stateful)

• Autoconfiguration (Stateless)

An IPv6 host can configure a link-local address for each interface automatically. By using ICMPv6 router discovery messages, a host can also determine the addresses of routers, additional addresses, and other configuration parameters.

Built-in Security

IPSec is built into IPv6 unlike IPv4 in which it is optional. IPSec requirement is mandatory in IPv6 Protocol Suite Implementation. IPv6 networks have potentially more end-to-end security because of IPSec availability on all nodes.

Extensibility

New futures for IPv6 can be added through the use of Extension Headers. At present there are various Extension Headers specified for QoS, Security, Mobility and Routing purposes.

Mobility

Mobility is built in to IPv6 which allows any node to use Mobile IP. Mobility is achieved using Mobility Extension Headers.

Better Quality of Service Support

IPv6 Header includes a new field called Flow Label that allows routers to identify and provide special handling for packets that belong to a particular flow. This field allows for easier identification of traffic without doing any tricks even when the packet payload is encrypted with IPSec.

Neighbor Discovery Protocol

Neighbor Discovery Protocol uses ICMPv6 messages to perform various functions such as

• Stateless Auto-configuration

• Router Discovery

• Prefix Discovery

• Address Resolution

• Neighbor Unreachability Detection

• Link MTU Discovery

• Duplicate Address Detection

• Next Hop Determination

Transition

The transition options supported by IPv6 to transition from IPv4 are another key feature of the protocol. Many Transitions mechanism are available for different scenarios. They are mentioned below

• Dual-Stack
• Tunneling IPv6 over IPv4 networks
• Protocol Translation

Within each option are various different techniques to support transition. A few tunneling mechanism are mentioned below

• Static GRE Tunnels

• 6to4 Tunnels

• ISATAP

• Automatic IPv4-Compatible IPv6 Tunnels

These rich features of IPv6 enable easy deployment, migration and operation of IPv6 networks.

More Related:  Cisco, Why We Need IPv6 Now?

Notes: IPv4 vs IPv6

The “v” and number (“4″ or “6″) in “IPv4 vs IPv6″ refers to the related protocol version number. “IPv4″ is of course “Internet Protocol version 4″, and “IPv6″ is subsequently “Internet Protocol version 6″.

IPv4 is of course the older, more supported version of the internet address procedure. But ultimately, there are no longer any free IPv4 addresses, meaning all of them have been occupied or taken up. What does this mean exactly?

In a general sense, there will no longer be any alternative IPv4 addresses, directly meaning they will all be occupied and new users will not be able to venture into cyberspace. Although the realistic situation is not quite as dire.

Queue in IPv6, the latest Internet Protocol or address procedure. The older IPv4 only supports a maximum 32 bit internet address, which translates to 2^32 IP addresses available for assignment (about 4.29 billion total). IPv6 utilizes 128 bit web addresses, allowing a maximum 2^128 available addresses: 340,282,366,920,938,000,000,000,000,000,000,000,000; which if you couldn’t already tell is a very big number.

So basically the IPv4 protocol has run out of available addresses which is why most websites or internet servers are adopting the newer IPv6 protocol. In most cases, the two versions are compatible. This contrast between the two protocol versions is exactly what’s being referred to when “IPv4 vs IPv6″ is mentioned.

Reard more:http://blog.router-switch.com/2012/01/main-feature-of-ipv6/

09-01-2012, 08:36 Geschreven door karenluo87