IP Addressing History Sequencer

About this interactive

Open standards such as IP are published as RFCs, requests for comments, and a newer RFC can replace an older one. The history of IPv4 addressing is a chain of RFCs, each fixing what the last one could not. RFC 760 (1980) made the first octet the network and the other 24 bits the host. Eight network bits allow only 256 networks, each with millions of hosts. RFC 791 (1981) brought classes: Class A keeps one octet for the network, Class B two and Class C three, which gives millions of networks. Classful networks were still too big, so RFC 950 (1985) brought subnetting: draw one more line inside a classful network, the same line for every subnet. Variable-length subnet masks (VLSM) and classless addressing (CIDR, RFCs 1518 and 1519 in 1993; RFC 1878 in 1995) let each subnet draw its line in a different place, so each network is the size it needs. Private addressing (RFC 1597 in 1994, replaced by RFC 1918 in 1996) set aside ranges that any organization can reuse inside its own network, translated to a public address at the gateway. IPv6 (RFC 1883 in 1995, RFC 2460 in 1998, today RFC 8200) is the long-term fix: 128-bit addresses instead of 32-bit ones. The video gives RFC 1918 and RFC 2460, the versions in use for most of the years since; either way the order is the same. The video also says IPv4 has "10 to the 32nd" addresses and IPv6 "10 to the 128th": that is a slip. Each bit doubles the count, so it is 2^32, about 4.3 billion, and 2^128, about 3.4 × 10^38. The cards carry no dates or RFC numbers. Ask of each one what shortage it fixed, and what shortage was left after it.

What you'll learn

Put the main changes to IP addressing in the order they came, from the first-octet network of 1980 to IPv6
Explain each change as the fix for the shortage the one before it left: too few networks, networks far too large, and finally too few addresses

Aligned to

CompTIA Network+

1.7 Given a scenario, use appropriate IPv4 network addressing.

Cisco CCNA

1.6 Configure and verify IPv4 addressing and subnetting

1.7 Describe private IPv4 addressing

Cisco CCST Networking

2.2 Identify IPv4 addresses and subnet formats

Key terms

Request for Comments: A formally published document from the IETF that defines standards, protocols, and best practices governing internet technologies and IP addressing.
Classful Addressing: An early IPv4 addressing scheme that divided the address space into fixed classes (A, B, and C for hosts; D for multicast; E reserved) based on the leading bits of the address, with each class defining a fixed boundary between the network and host portions. Classful addressing was replaced by CIDR because it wasted large blocks of address space.
Subnet: A logical subdivision of an IP network, used to organize and segment network traffic.
Variable Length Subnet Mask: A subnetting technique that allows a network administrator to divide an address space into subnets of different sizes by using different prefix lengths, allocating address space more efficiently than fixed-length subnetting. VLSM requires a classless routing protocol such as OSPF, EIGRP, or RIPv2 that carries prefix length information in routing updates.
Classless Inter-Domain Routing: A method for allocating IP addresses and expressing routing prefixes that replaces the older classful addressing scheme by using variable-length prefix notation (e.g., /24). CIDR enables more efficient use of IPv4 address space and reduces the size of internet routing tables through route aggregation.
Private Addressing: A set of IP address ranges reserved for use within private networks that are not routable on the public internet, defined by RFC 1918.
IPv4: The fourth version of the Internet Protocol, using 32-bit addresses that provide approximately 4.3 billion unique addresses.

Topics

Ip Address History Rfc Classful Addressing Subnetting Vlsm Private Addressing Interactive Ordering

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