IPv4 to IPv6 Address Converter
Understanding IPv4 to IPv6 Conversion
As the internet transitions from the legacy IPv4 protocol to the modern IPv6 standard, interoperability mechanisms are crucial. Direct conversion from an arbitrary IPv6 address to IPv4 is generally not possible due to the vast difference in address space size ($2^{128}$ vs $2^{32}$). However, mapping an IPv4 address into an IPv6 address is a standard procedure used by networking stacks and transition technologies.
IPv4-Mapped IPv6 Addresses
The most common conversion format is the IPv4-mapped IPv6 address. This format allows an IPv6-enabled host to represent an IPv4 node internally. The structure consists of an 80-bit prefix of zeros, followed by 16 bits of ones, and finally the 32-bit IPv4 address.
The mathematical representation is: \[ \text{Prefix} = 0:0:0:0:0:\text{FFFF} \] \[ \text{Address} = \text{Prefix} : \text{IPv4}_{\text{High}} : \text{IPv4}_{\text{Low}} \] For example, the IP 192.0.2.128 becomes ::ffff:c000:0280.
6to4 Transition Mechanism
6to4 is a system that allows IPv6 packets to be transmitted over an IPv4 network. It uses a specific prefix, 2002::/16. The 32-bit IPv4 address of the gateway is embedded directly after this prefix.
- Prefix: 16 bits (
0x2002) - IPv4 Embed: 32 bits (Derived from the public IPv4)
- Subnet/Interface: 80 bits (Available for local addressing)
Mathematical Formulas
To convert an IPv4 dotted-decimal string \( d_1.d_2.d_3.d_4 \) to a 32-bit integer \( I \):
\[ I = (d_1 \times 256^3) + (d_2 \times 256^2) + (d_3 \times 256^1) + (d_4 \times 256^0) \]This integer is then converted to Hexadecimal to form the suffix segments of the IPv6 address.