IP Addressing (IPv6 Part-I:Introduction, Differences in IPv4 & IPv6, Advantages of IPv6 over IPv4 & Transition Methods)

In the last post related to IP Addressing, I discussed about IPv4 basics. Now let me turn to the higher version of Internet Protocol-IPv6. As the name suggests, IPv6 succeeds IPv4. Now, every technology in this world comes with "versions".Likewise, Internet Protocol v.6 was developed by the Internet Engineering Task Force (IETF).

As I said in the previous post, IPv4 is a 32 bit address, which means that all over the world, there can be at the maximum 2³² or 4294967296 available addresses. Since the world population is growing drastically, these available addresses are on their way of being exhausted. This difficulty is removed by the use of IPv6 which is a  128-bit address. 

Consequently, there will be billions of addresses, the calculation will go beyond imagination!!!!!!!!!!

Before moving on any further, I will point out the differences between IPv4 and IPv6 and here they go-

As we have discussed the above differences, it is necessary to discuss the advantages of IPv6 over IPv4 and they are as follows:

 (i) Address Assignment Features- IPv6 address assignment allows easier renumbering, dynamic  

     allocation & easier recovery of addresses.

 (ii) Aggregation- IPv6 huge address space makes easier aggregation of blocks of addresses.

 (iii) No need for NAT/PAT- Using publicly unique addresses on all devices removes the need for 

      Network Address Translation (NAT) & Port Address Translation (PAT) which are used for converting

      private addresses into public addresses and vice versa.

 (iv) More Efficient Routing- IPv6 reduces the size of the routing tables and makes routing more efficient

       and hierarchical.

 (v) More Efficient Packet Processing- IPv6's packet header makes packet processing more efficient.

      Compared to IPv4, IPv6 contains no IP-level checksum*, so the checksum need not to be regulated at 

      every router hop. Getting rid of IP-level checksum was possible because most of the link layer 

      technologies today contain error control capabilities. (*checksum refers to simple error detection used

      in the IP header to protect the data against corruption. This checksum value is 16 bits long and is 

      contained only in the header part of the IP address)

 (vi) Directed Data Flows- IPv6 supports multicast rather than broadcast. Multicast allows bandwidth-

       intensive packet flows which allows packets sent to multiple destinations simultaneously. This

       saves the network bandwidth.

 (vii) IPSec Policies- IPSec (IP Security) which provides confidentiality, authentication and data integrity is

        included into IPv6. Since, IPv4 packets have a high potential to carry malware, they are often blocked

        by Internet firewalls. As IPSec is integrated into ICMP v6 packets, they are allowed through the 

        firewalls.

Today, almost every computer connected to the Internet is running on the IPv4 addressing scheme. The IETF has published the IPv4 to IPv6 transition methods in RFC 6144. Transitioning describes the methods

for moving from IPv4 addressing to IPv6 addressing. Following are the transitions methods:

  (i) Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)- ISATAP is used for automatic 

       deployment of IPv6 in IPv4 sites. ISATAP has been defined in RFC 4214. The word "automatic" in

      ISATAP denotes that once the ISATAP server has been set up, only the clients must be configured to

      connect to it. ISATAP uses IPv4 as a non-multicast/ broadcast-capable link layer, therefore, ICMPv6

      Neighbor Discovery cannot be done in a usual manner. Lack of multicast support prevents 

      the use of Automatic Neighbor Discovery, hence, the ISATAP hosts must be configured 

      with "Potential Router List" (PTR).

  (ii) Dynamic 6to4 Tunnels- In this type of transitioning, the system is capable of transmitting IPv6

       packets over an IPv4 network. This transition method is generally useful when IPv6 is deployed in the 

       network for the first time or is in it's initial phases of deployment. When this method is used by a 

       host, there should be an IPv4 address connected. 6to4 transitioning encapsulates IPv6 packets

       inside IPv4 network. An extension to the 6to4 transition method id called as "IPv6 rapid 

       deployment".

  (iii) Teredo Tunneling- In this type of transition, full IPv6 connectivity is given to the IPv6 capable hosts

        which are on the IPv4 network and have no direct connection to the native IPv6 network. Teredo 

        Tunneling uses Platform Independent Tunneling Protocol (PITP) which provide IPv6

        connectivity by encapsulating IPv6 datagram packets into IPv4 datagram packets.

   (iv) Stateless IP/ICMP Translation (SIIT)- SIIT translates packet header formats in IPv4 and IPv6.

   (v) Dual Stack-Lite (DS-Lite)- Due to the exhaustion of IPv4 addresses, DS-Lite was designed to 

        let the Internet Service Providers (ISPs) to omit the deployment of any IPv4 addresses to the 

        Consumer Premises Equipment (CPE).

   (vi) NAT64/DNS64- NAT64 is a transition method where IPv6 hosts are capable of communicating

        with the IPv4 servers. DNS64 is another transition method where the DNS server is asked for the 

        AAAA records but the DNS server finds only the A records. Eventually, the DNS server returns 

        the results for AAAA records on the basis of A records 

The above transition methods are a bit difficult to understand for those who are new to the field of network-
-ing. However, while reading the above transition methods, one must remember that the above methods 
describe how one can move from IPv4 to IPv6. Implementing the above transition methods is a complex 
task that is carried out by network engineers.

Now, I hope you have understood the differences between IPv4 and IPv6, the advantages of IPv6 over IPv4 and the transition methods that can be used. Let me move to more details of the IPv6 concept.
First of all, let me show you how an IPv6 address is written. As you must be knowing by now that IPv6 is an 128-bit address, divided into a group of 4 hexadecimal digits, an example you may take:

   2340:1111:AAAA:0001:1234:5678:9ABC

Another example might be 2001:0ad8:84b3:0000:0000:8a2c:8b3d:8224. Since, IPv6 addresses have a 

considerable length, they can be shortened systematically. There are two conventions that allow the 

shortening of IPv6 addresses:

   (i) Omit the leading zeros (0s) is any given quartet.

   (ii) Represent 1 or more consecutive quartets of all the hex 0s with a double colon (::). However, writing

        :: is allowed only once in an IPv6 address.

Now, if I consider the above IPv6 address and decide to shorten it, then the result will be:

2001:0ad8:84b3::8a2c:8b3d:8224

To conclude with part I of IPv6, please remember that every quartet in an IPv6 address contains 16 bits

i.e. 16 x 8= 128 bits in the whole IPv6 address.

In the next IPv6 article, we will go deeper into the IPv6 concept, so keep in touch with my blog.

Till then, keep reading & thanx a lot!