From the Early American Internet to Modern Internet Protocol Addressing
Internet Protocol addresses identify interfaces participating in Internet Protocol communication. Modern Internet communication primarily uses two versions of IP: Internet Protocol version 4 (IPv4) and Internet Protocol version 6 (IPv6).
The modern Internet developed from decades of American computer-networking research. One of the most important early projects was the Advanced Research Projects Agency Network, better known as ARPANET.
DARPA identifies 1969 as the year in which the first four ARPANET nodes became operational. Those nodes were located at:
(DARPA, n.d.)
EARLY DEVELOPMENT OF THE AMERICAN INTERNET ========================================== 1960s | | U.S. research into packet-switched networking | v 1969 | | ARPANET | | +-----------+ | | UCLA | | +-----------+ | | | | | +-----------+ | | SRI | | +-----------+ | | | +------------------+ | | | +---------------+ | | UC Santa | | | Barbara | | +---------------+ | | | +---------------+ | | University | | | of Utah | | +---------------+ | v 1970s Development of internetworking and TCP/IP concepts | v 1981 RFC 791 Internet Protocol DoD / DARPA Internet Program | v January 1983 ARPANET transitions to TCP/IP | v THE INTERNET | +---------------------+ | | v v IPv4 IPv6 32-bit 128-bit addressing addressing
DARPA explains that research by Robert Kahn, Vinton Cerf, and others contributed to the development of TCP/IP and that ARPANET transitioned to TCP/IP in January 1983. The Internet Society similarly describes the development of TCP/IP as a foundation for an open-architecture network in which independently operated networks could communicate with one another (DARPA, n.d.; Internet Society, 2012).
In September 1981, Jon Postel edited RFC 791, Internet Protocol. The document describes itself as the DoD Standard Internet Protocol and states that it was based upon earlier ARPA Internet Protocol specifications (Postel, 1981).
Internet Protocol provides addressing that allows packets, traditionally called datagrams, to travel through interconnected networks. RFC 791 explains the distinction in particularly useful terms: a name identifies what is being sought, an address identifies where it is, and a route determines how to reach it (Postel, 1981).
INTERNET COMMUNICATION
+------------+ +------------+
| Computer A | | Computer B |
| | | |
| IP Address | | IP Address |
+-----+------+ +------+-----+
| ^
| |
v |
+-------------+ +-------------+ |
| Router | ----> | Router | --------+
+-------------+ +-------------+
IP packet
+-----------------------------+
| Source IP Address |
| Destination IP Address |
| Other IP Header Information |
| Data |
+-----------------------------+
IPv4 uses a 32-bit address. Those 32 bits are normally represented as four 8-bit sections called octets. Each octet is normally written as a decimal number from 0 through 255 (Frankel et al., 2010; Postel, 1981).
IPv4 ADDRESS
============
32 total bits
+----------+----------+----------+----------+
| 8 bits | 8 bits | 8 bits | 8 bits |
+----------+----------+----------+----------+
| Octet 1 | Octet 2 | Octet 3 | Octet 4 |
+----------+----------+----------+----------+
8 + 8 + 8 + 8 = 32 bits
192.168.1.25
Decimal representation
+-------+-------+-------+-------+
| 192 | 168 | 1 | 25 |
+-------+-------+-------+-------+
| | | |
v v v v
Octet Octet Octet Octet
1 2 3 4
Each IPv4 octet consists of eight binary positions:
Binary place values for one octet: +-----+----+----+----+----+---+---+---+ | 128 | 64 | 32 | 16 | 8 | 4 | 2 | 1 | +-----+----+----+----+----+---+---+---+
For example:
192 128 + 64 = 192 128 64 32 16 8 4 2 1 | | | | | | | | 1 1 0 0 0 0 0 0 192 = 11000000 168 128 + 32 + 8 = 168 128 64 32 16 8 4 2 1 | | | | | | | | 1 0 1 0 1 0 0 0 168 = 10101000
Decimal:
192 . 168 . 1 . 25
Binary:
11000000 . 10101000 . 00000001 . 00011001
ASCII breakdown:
+----------+----------+----------+----------+
|11000000 |10101000 |00000001 |00011001 |
+----------+----------+----------+----------+
| 192 | 168 | 1 | 25 |
+----------+----------+----------+----------+
32 TOTAL BITS
Because an IPv4 address contains 32 bits, the theoretical address space is:
2^32 = 4,294,967,296 approximately 4.3 billion addresses
NIST compares IPv4's 232 address space with IPv6's much larger 2128 address space (Frankel et al., 2010).
Modern IPv4 networks commonly use Classless Inter-Domain Routing
prefix notation. A prefix such as /24 means that the first
24 bits belong to the network prefix.
192.168.1.0/24
Address:
192 168 1 0
11000000.10101000.00000001.00000000
|-----------------------| |-------|
24 bits 8 bits
NETWORK PREFIX HOST
Network:
192.168.1.0/24
Host:
192.168.1.25
NETWORK HOST
| |
v v
11000000.10101000.00000001 . 00011001
|-------------------------| |--------|
24 bits 8 bits
IPv6 was designed as the successor to IPv4. RFC 8200 states that one of the principal changes is an increase in address size from 32 bits to 128 bits (Deering & Hinden, 2017).
NIST likewise describes an IPv6 address as 128 bits long and generally written as eight 16-bit hexadecimal fields separated by colons (Frankel et al., 2010).
IPv6 ADDRESS
============
128 total bits
+--------+--------+--------+--------+
|16 bits |16 bits |16 bits |16 bits |
+--------+--------+--------+--------+
| Group 1| Group 2| Group 3| Group 4|
+--------+--------+--------+--------+
+--------+--------+--------+--------+
|16 bits |16 bits |16 bits |16 bits |
+--------+--------+--------+--------+
| Group 5| Group 6| Group 7| Group 8|
+--------+--------+--------+--------+
8 groups x 16 bits
=
128 bits
IPv6 is normally written in hexadecimal rather than decimal. Hexadecimal contains 16 symbols:
Decimal Hexadecimal ------- ----------- 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 A 11 B 12 C 13 D 14 E 15 F
2001:0db8:1234:5678:abcd:ef01:2345:6789 | | | | | | | | v v v v v v v v +----+----+----+----+----+----+----+----+ |2001|0db8|1234|5678|abcd|ef01|2345|6789| +----+----+----+----+----+----+----+----+ 1 2 3 4 5 6 7 8 Each group = 16 bits 8 x 16 = 128 bits
One hexadecimal digit represents 4 binary bits.
Hexadecimal:
A
Binary:
1010
Therefore:
4 hexadecimal digits
x
4 bits per hexadecimal digit
=
16 bits
Example:
2001
2 0 0 1
| | | |
v v v v
0010 0000 0000 0001
\__________ __________/
\/
16 bits
The theoretical IPv6 address space is:
2^128 = 340,282,366,920,938,463,463,374,607,431,768,211,456 approximately 3.4 x 10^38 addresses
This enormous address space is one of the fundamental differences between IPv4 and IPv6 (Deering & Hinden, 2017; Frankel et al., 2010).
IPv6 includes notation rules that make long addresses easier for humans to write and read.
Original: 2001:0db8:0000:0000:0001:0000:0000:0001 Remove leading zeros from individual groups: 2001:db8:0:0:1:0:0:1
Before: 2001:db8:0:0:0:0:0:1 Compressed: 2001:db8::1
The double colon :: represents the omitted contiguous
zero-valued groups. It can be used only in a way that leaves the address
unambiguous.
Full conceptual form: 0000:0000:0000:0000:0000:0000:0000:0001 Compressed form: ::1
IPv6 also uses prefix notation.
A /64 prefix means that the first 64 bits represent the
network prefix.
2001:db8:abcd:1234:5678:90ab:cdef:1234/64
|--------- NETWORK PREFIX ---------|--------- INTERFACE ---------|
2001 : db8 : abcd : 1234 : 5678 : 90ab : cdef : 1234
\________________________/ \________________________/
| |
v v
64 bits 64 bits
TOTAL = 128 bits
| Characteristic | IPv4 | IPv6 |
|---|---|---|
| Address size | 32 bits | 128 bits |
| Basic notation | Decimal | Hexadecimal |
| Separator | Period / dot | Colon |
| Example | 192.168.1.25 |
2001:db8::25 |
| Number of sections | 4 octets | 8 hexadecimal groups when fully written |
| Bits per section | 8 | 16 |
| Total theoretical addresses | 232 | 2128 |
| Approximate address space | 4.3 billion | 3.4 × 1038 |
IPv4
====
32 bits
8 8 8 8
+---------+---------+---------+---------+
| Octet 1 | Octet 2 | Octet 3 | Octet 4 |
+---------+---------+---------+---------+
Example:
192.168.1.25
------------------------------------------------------------
IPv6
====
128 bits
16 16 16 16
+--------+--------+--------+--------+
|Group 1 |Group 2 |Group 3 |Group 4 |
+--------+--------+--------+--------+
16 16 16 16
+--------+--------+--------+--------+
|Group 5 |Group 6 |Group 7 |Group 8 |
+--------+--------+--------+--------+
Example:
2001:db8:1234:5678:abcd:ef01:2345:6789
AMERICAN INTERNET HISTORY
=========================
1960s
|
v
Packet-switching research
|
v
1969
|
v
+-------------+
| ARPANET |
+-------------+
|
|
v
1970s
|
v
TCP/IP development
Cerf, Kahn, Postel,
DARPA researchers
|
v
September 1981
|
v
+-----------+
| RFC 791 |
| IPv4 |
+-----------+
|
v
January 1983
|
v
ARPANET transitions to TCP/IP
|
v
Growth of Internet
|
v
IPv4 address pressure
|
v
IPv6 development during
the 1990s
|
v
+-----------+
| IPv6 |
| 128 bits |
+-----------+
|
v
RFC 8200
2017
|
v
Modern Internet
The historical progression is important because IPv6 did not replace the basic purpose of Internet Protocol. Instead, it extended the architecture developed through earlier American networking research while substantially expanding addressing capabilities. RFC 8200 explicitly describes IPv6 as the successor to IPv4 (Deering & Hinden, 2017).
Students do not have to rely on commercial textbooks alone to study this material. Several of the foundational and modern specifications are publicly available from United States government agencies and public standards organizations.
SOURCE INFORMATION
=======================================================================
DARPA ARPANET history
darpa.mil Early American networking
TCP/IP development
RFC Editor RFC 791
rfc-editor.org Original Internet Protocol specification
IPv4 technical architecture
RFC Editor RFC 8200
rfc-editor.org Modern IPv6 specification
NIST IPv4 / IPv6 technical comparison
nist.gov Federal IPv6 standards and security
NIST CSRC Secure IPv6 deployment guidance
csrc.nist.gov
CISA Federal IPv6 deployment and
cisa.gov cybersecurity guidance
Internet Society Historical Internet development
internetsociety.org TCP/IP and open-network architecture
NIST's IPv6 work is particularly useful when studying networking from a United States public-sector perspective. NIST developed an IPv6 profile specifically to help U.S. federal agencies acquire and deploy interoperable IPv6 technologies (Montgomery et al., 2008; Montgomery et al., 2020).
CISA likewise provides public guidance concerning secure IPv6 deployment within federal information systems. CISA notes that federal IPv6 transition policy dates to 2005 and that the federal government renewed its IPv6 transition effort in 2020 (Cybersecurity and Infrastructure Security Agency, 2021).
IPv4
----
32 bits
4 octets
8 bits per octet
Decimal notation
Example:
192.168.1.25
versus
IPv6
----
128 bits
8 groups when fully written
16 bits per group
Hexadecimal notation
Example:
2001:db8:1234:5678:abcd:ef01:2345:6789
Most important numerical relationship:
IPv4 = 2^32 possible bit patterns
IPv6 = 2^128 possible bit patterns
IPv4 traces directly to the Internet Protocol developed through the DARPA Internet Program and formally documented in RFC 791 in 1981. IPv6 retains the Internet Protocol concept while dramatically increasing the addressing space from 32 to 128 bits. The history therefore connects some of the earliest American packet-networking research directly to the addressing systems used on today's Internet.
APA 7th Edition
Cybersecurity and Infrastructure Security Agency. (2021). Internet Protocol version 6 considerations for Trusted Internet Connections 3.0. https://www.cisa.gov/sites/default/files/2023-02/ipv6_considerations_for_tic_3.0_draft_0.pdf
Defense Advanced Research Projects Agency. (n.d.). ARPANET. https://www.darpa.mil/about/innovation-timeline/arpanet
Deering, S., & Hinden, R. (2017). Internet Protocol, version 6 (IPv6) specification (RFC 8200). RFC Editor. https://doi.org/10.17487/RFC8200
Frankel, S., Graveman, R., Pearce, J., & Rooks, M. (2010). Guidelines for the secure deployment of IPv6 (NIST Special Publication 800-119). National Institute of Standards and Technology. https://doi.org/10.6028/NIST.SP.800-119
Internet Society. (2012). Brief history of the Internet. https://www.internetsociety.org/wp-content/uploads/2017/09/ ISOC-History-of-the-Internet_2012Oct.pdf
Montgomery, D. C., Nightingale, J. S., Frankel, S. E., & Carson, M. E. (2008). A profile for IPv6 in the U.S. Government—Version 1.0 (NIST Special Publication 500-267). National Institute of Standards and Technology. https://doi.org/10.6028/NIST.SP.500-267
Montgomery, D. C., Carson, M. E., Winters, T., Newcombe, M., & Carlin, T. (2020). USGv6 profile (NIST Special Publication 500-267Br1). National Institute of Standards and Technology. https://doi.org/10.6028/NIST.SP.500-267Br1
Postel, J. (1981). Internet Protocol (RFC 791). RFC Editor. https://doi.org/10.17487/RFC791