Transition from IPv4 to IPv6

The transition from IPv4 to IPv6 is necessary because IPv4 addresses are running out. IPv6 provides a larger address space (128 bits compared to IPv4's 32 bits). However, transitioning between the two protocols is not straightforward, as they are not directly compatible. Therefore, multiple techniques are used to make this transition smooth and gradual.

Key Points:

1. Why Transition?

   • IPv4 supports about 4.3 billion unique addresses, which is insufficient due to the growing number of devices (phones, computers, IoT).
   • IPv6 uses 128-bit addresses, providing 340 undecillion unique addresses, which is practically unlimited.

2. Transition Techniques: The key methods used for the transition are:

   • Dual Stack: Both IPv4 and IPv6 run on the same devices, allowing communication over both protocols.
   • Tunneling: IPv6 packets are encapsulated in IPv4 packets to travel over an IPv4 network.
   • NAT64: Allows IPv6-only devices to communicate with IPv4-only devices.

Example of Dual Stack Transition:

Scenario: A company is transitioning its internal network from IPv4 to IPv6. Initially, they have a server with an IPv4 address: 192.168.1.10.

Step 1: The company configures their server to support both IPv4 and IPv6 (dual stack). The server now has two addresses:

• IPv4 address: 192.168.1.10
• IPv6 address: 2001:0db8:85a3::10

Step 2: During the transition, users with IPv6-capable devices can access the server using the IPv6 address (2001:0db8:85a3::10), while users with only IPv4 devices will still access the server using the IPv4 address (192.168.1.10).

Step 3: Over time, more devices in the network are upgraded to IPv6. Eventually, the company phases out IPv4, and only IPv6 is used.

Benefits:

• Coexistence: Dual stack allows both IPv4 and IPv6 to coexist, so there is no disruption in service during the transition.
• Gradual Migration: The company can continue using IPv4 while gradually shifting to IPv6.