IP-in-IP Encapsulation

In this article, we will discuss the overview of IP-in-IP Encapsulation and then will discuss the working and its process of encapsulation, and then finally conclude and will discuss the Logical and Physical views of the IP-in-IP encapsulation process. Let’s discuss it one by one.

Encapsulation :
In simple terminology, Encapsulation is basically the process of adding a new packet within the existing packet. Destination Address field. In network communication, the packet is the smallest unit of information, and the basic packet contains the information of header which is important while communication, the basic packet contains information of both sender and receiver header. On the sending system, when protocol, added data to the packet header then the process called data encapsulation. Hence, we can term encapsulation the act of packaging data or adding each layer’s header to the actual data. So, when data gets at the Transport layer, it is no longer called data, it is rather termed as a segment in Networking Terminology. Also, when the segment gets at the Network layer, it is no longer called a segment, it is rather termed as a packet. 

Encapsulation in Network Protocols :
For Instance, let’s assume that we have an IPv6(Internet Protocol Version 6). So whenever, this packet reaches the router where the router supports only IPv4(Internet Protocol Version 4). Now there is no way that the information is transmitted. This is where the IP in IP Encapsulation comes into the picture. With the use of this Encapsulation process, we can add a new packet within the existing one so that the information is passed efficiently.

Process of Encapsulation :
Firstly, take the IPv6 packet which is receiving, and since the router does not support IPv6, we take that receiving packet, and then on the top of the received packet, we wrap with a new packet which is called IPv4. Here, we are not touching the IPv6 address. We are just keeping it intact and since the router supports only IPv4, we are adding a new IP 20-byte header wherein we will be having a 32 bit IP address for Source and Destination. This is the process of IP-in-IP Encapsulation.

Logical and Physical views of the IP-in-IP encapsulation process :
Consider the following Logical and Physical views of the IP-in-IP encapsulation process respectively. Now, you will see the explanation part of Logical and Physical views of the IP-in-IP encapsulation process as follows.

• Here A, B, C, D, E, F are the routers in a network. In this example, the Source address is A and the destination address is F. So, the packet is generating at router A and the packet has to reach router F. 
• Firstly, the packet reaches from source A to source B without any trouble. Now, since router C supports only IPv4, the received IP header is not touched or changed. But here, the new packet is added to the received packet where the Source node is B and the Destination node is E. That means B is adding the IPv4 address because C supports only IPv4. So, in order to send the data from B to C, we need to use IPv4 because C supports only IPv4. 
• Another takeaway from this diagram is that the link from A to B is connected with IPv6 whereas the link from B to C is connected with IPv4. 
• This means that Router B both IPv4 and IPv6. The same encapsulated packet is transferred till router D. So, as soon as the packet reaches the source D, this link will be deleted because the next link i.e from D to E is already IPv6 which means that the node can directly the inner packet(inner IPv6 packet). In this way, the IP-in-IP Encapsulation works when the adjacent routers don’t have the same IP version support.