IPv4
IPv4 (Internet Protocol version 4) is the fourth version of the Internet Protocol (IP), which is the communication protocol responsible for routing and addressing data packets across network boundaries. Here's detailed information on IPv4:
History and Development
- IPv4 was first described in September 1981 by DARPA in RFC 791, which was written by Jon Postel.
- It was developed to facilitate internetworking and the establishment of a universal protocol for the internet.
Addressing
- IPv4 uses 32-bit addresses, allowing for approximately 4.3 billion unique addresses.
- The address space is divided into classes (A, B, C, D, and E) for network management:
- Class A for large networks with 16 million hosts.
- Class B for medium-sized networks with 65,536 hosts.
- Class C for small networks with 256 hosts.
- Class D for multicast groups.
- Class E reserved for future use or experimental purposes.
- Subnetting allows for the division of networks into smaller, more manageable units, conserving address space.
Features
- Connectionless: IPv4 operates in a connectionless manner, meaning each packet is treated independently.
- Datagram: Data is transmitted in small chunks called datagrams, which are routed independently.
- Checksum: Includes a header checksum to detect errors in the packet header.
- Fragmentation: Allows packets to be broken into smaller pieces if they exceed the Maximum Transmission Unit (MTU) of the network.
- Time to Live (TTL): Ensures that undeliverable packets do not circulate indefinitely on the network.
Limitations
- The finite address space of IPv4 has led to address exhaustion, prompting the development of IPv6.
- Network Address Translation (NAT) was introduced to extend the life of IPv4 by allowing multiple devices to share a single public IP address.
- Security was not a primary concern in the original design, leading to the implementation of additional protocols like IPSec.
Deployment and Usage
- Despite the introduction of IPv6, IPv4 remains widely used due to the large existing infrastructure.
- Many organizations still use IPv4 exclusively or use both protocols in a dual-stack configuration.
Future and Transition
- Transition to IPv6 has been gradual, with various mechanisms in place to support both protocols:
- Dual-stack: Running both IPv4 and IPv6 simultaneously on devices and networks.
- Tunneling: Encapsulating IPv6 packets within IPv4 packets to traverse IPv4 networks.
- Translation: Converting between IPv4 and IPv6 headers to facilitate communication.
External Links
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