IPv6 introduced great enhancements to IPv4. The improvements include Mobility, security, smaller header, address formatting.
Mobility is a new, IPv6 feature. Mobility allows users with mobile network devices to change locations around the network. Mobile IP is an IETF standard that is available for IPv4 as well as IPv6. This standard permits mobile devices to move without disruptions in established networks.
IPSec is another IETF standard for IP network security. It is offered by both protocols. The IP net security characteristics are similar in both environments. IPSec is improved in IPv6 and can be enabled on every node that uses this protocol.
Smaller Header
The header used for IPv6 improves routing efficiency by decreasing the number of records in the routing tables. No broadcasts are produced by IPv6. IPv4 creates broadcasts that generate a high level of network traffic. This network traffic produces an event known as a broadcast storm and the whole network stops functioning. IPv6 replaced broadcast traffic with multicast and anycast traffic.
Address Formatting
The hexadecimal digits A, B, C, D, E, and F represented in IPv6 addresses are not case-sensitive. The IPv6 address string format is not fixed. The next rules are used for IPv6 address string notations: The first 0s in a field are optional. For example 09C0 equals 9C0 and 0000 equals 0. One or more sets of 0s can be deleted and replaced with “::”. Also, only one “::” is permitted in an address.
The “::” symbolization greatly shrinks the size of most IP addresses. For instance, FF01:0:0:0:0:0:0:1 becomes FF01::1. The primary type of IPv6 address is called unicast. Unicast transmits packets to a particular device with one specific IP address. Multicast transmits an IP packet to every member of a group. Anycast transmits an IP packet to all the devices that have an anycast address assigned. Anycast traffic can also be thought of as a one-to-nearest type of traffic.
Reserved Addresses
A portion of the IPv6 address space is reserved for various uses. IPv6 supports considerably more reserved addresses than IPv4. A range of IPv6 addresses is reserve for private addresses. Private addresses have a first octet value of FE in hexadecimal notation.
Transition Richness
There are numerous methods to integrate an IPv6 net into an existing IPv4 net. The conversion from IPv4 to IPv6 does not have to be completed all at once. Three common transition methods are 1. Dual stack, 2. Tunneling, 3. Proxying and translation
In the dual-stack IPv4 and IPv6 configurations are applied on a network appliance. Both protocol stacks run on the same network device. This method allows IPv4 and IPv6 to live together.
Tunneling is a method that is becoming more popular as the acceptance of IPv6 grows. Tunneling is the encapsulation of one protocol packet within another protocol. For instance, an IPv6 packet can be encapsulated within an IPv4 protocol.
Some network devices may include a Network Address Translation-Protocol. This translation permits direct communication between network devices that use different versions of the IP protocol.
If you want to configure a router to locally resolve hostnames to IPv6 addresses, use the ipv6 hostname ipv6addr command. To configure an external DNS server to resolve IPv6 addresses, use the IP name-server address command. Enabling name resolution on a network device helps the administrator to access other devices on the network by name. It does not disturb the operation of the router and does not advertise this DNS server name to DHCP clients.
Hope you got the basics of this protocol cleared up.