What is IPv6 used for? With example

In this tutorial, we are going to see What is IPv6 used for? With example.

The days of IP in its current form (IPv4) are over. The Internet was widely used by universities, high-tech industries, and government by the mid-1990s, but the Internet is increasingly becoming a concern for businesses and commercial enterprises – it will be used by a large number of individuals and systems each with different needs. For example, video-on-demand, home shopping, or e-commerce. Under these conditions, the IPv6 protocol (also called IPng for IP new generation) should offer more flexibility and efficiency, solve a variety of new problems, and should never be out of addresses.

 
The main goals of this new protocol were to:

• Support billions of computers, get rid of the inefficiency of the current IP address space,
• Reduce the size of routing tables,
• Simplify the protocol, to allow routers to route datagrams faster,
• Provide better security (authentication and privacy) than the current IP protocol,
• Pay more attention to the type of service, especially services associated with real-time traffic,
• Facilitate multicast by allowing scope specification,
• Give the possibility to a computer to move without changing its address,
• Allow the protocol to evolve in the future,
• Allow the old and new protocols to coexist peacefully.

 

 

IPv6

IPv6 reasonably meets the stated goals. It maintains the best features of IPv4, discards or minimizes the bad ones, and adds new ones when needed.

In general, IPv6 is not compatible with IPv4, but is compatible with all other Internet protocols, including TCP, UDP, ICMP, IGMP, OSPF, BGP, and DNS; sometimes slight modifications are required (especially to work with long addresses).

The most important new feature of IPv6 is the usage of longer addresses than IPv4. They are encoded on 16 bytes to provide an unlimited set of Internet addresses.

IPv4 can address 2^32=4.29.10^9 addresses while IPv6 can address 2^128=3.4.10^38 addresses.

The major improvement of IPv6 is the improvement of the datagram header. The basic IPv6 datagram header consists of only 7 fields (compared to 14 for IPv4). This change allows routers to process datagrams faster and improves their speed as a result.

The third improvement is to provide more flexibility in options. This change is essential with the new header, as the mandatory fields of the old version have now become optional.

In addition, the way the options are represented is different; it makes it easier for routers to ignore options that are not intended for them. This feature speeds up the datagram processing time.

On the other hand, IPv6 provides greater security: Authentication and privacy are the major security features of IPv6.
 

 

Basic Header of IPv6 Datagrams

Here is what an IPv6 datagram looks like:
 

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Here is the meaning of the different fields:

• The Version field is always equal to 4 bits for IPv6. During the migration from IPv4 to IPv6, routers will need to examine this field to determine what type of datagram they are routing.

 


 
• The Traffic Class field (encoded in 8 bits) is used to distinguish between sources that should receive flow control and those that should not. Priorities from 0 to 7 are assigned to sources that are capable of slowing down their flow in case of congestion. Values 8 to 15 are assigned to real-time traffic (including audio and video) that has a constant bandwidth.
  This distinction of flows allows routers to better respond in case of congestion. Within each priority group, the lowest priority level corresponds to the most important datagrams.
• The Flow Label field contains a unique number chosen by the source that is intended to facilitate the work of routers and enable the implementation of QoS functions such as RSVP (Resource reSerVation setup Protocol). This flag can be considered as a flag for a given context in the router. The router can then perform particular processing: choice of a route, “real-time” processing of the information, etc…
• The Payload length field, which is two bytes long, contains only the size of the payload, without taking into account the length of the header. For packets with a data size greater than 65536 this field is set to 0 and the jumbogram option of the near-end extension is used.
• The Next Header field has a similar function to the protocol field of the IPv4 packet: It simply identifies the next header. It can be a protocol (top-level ICMP, UDP, TCP, …) or an extension.
• The Hop Limit field replaces the “TTL” (Time-to-Live) field in IPv4. Its value (on 8 bits) is decremented at each node crossed. If this value reaches 0 while the IPv6 packet is crossing a router, it will be rejected with the emission of an ICMPv6 error message. It is used to prevent datagrams from circulating indefinitely. It plays the same role as the IPv4 lifetime field, it contains a value representing the number of hops that is decremented each time a router passes through.
• Then the Source Address and Destination Address fields.

 

 

IPv6 notation:

A new notation has been defined to describe 16-byte IPv6 addresses. It consists of 8 groups of 4 hexadecimal digits separated with a colon. For example:

9000:0000:0000:0000:0635:9103:AF23:12AB

Since many addresses have many zeros in their name, 3 optimizations have been defined. First, the first zero of a group can be omitted, for example, 0635 which can be written 635. Then, one or more groups of 4 consecutive zeros can be replaced by a double colon. This is how the above address becomes:

9000::::635:9103:AF23:12AB

Finally, IPv4 addresses can be written using the address representation in dotted decimal notation preceded by a double colon, such as:

::125.44.122.24

 
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