Assigned numbers
RFC 790
Document | Type |
RFC - Historic
(September 1981; No errata)
Obsoleted by RFC 820
Obsoletes RFC 776
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Authors | |||
Last updated | 2013-03-02 | ||
Stream | Legacy | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | Legacy state | (None) | |
Consensus Boilerplate | Unknown | ||
RFC Editor Note | (None) | ||
IESG | IESG state | RFC 790 (Historic) | |
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group J. Postel Request for Comments: 790 ISI September 1981 Obsoletes RFCs: 776, 770, 762, 758, 755, 750, 739, 604, 503, 433, 349 Obsoletes IENs: 127, 117, 93 ASSIGNED NUMBERS This Network Working Group Request for Comments documents the currently assigned values from several series of numbers used in network protocol implementations. This RFC will be updated periodically, and in any case current information can be obtained from Jon Postel. The assignment of numbers is also handled by Jon. If you are developing a protocol or application that will require the use of a link, socket, port, protocol, or network number please contact Jon to receive a number assignment. Jon Postel USC - Information Sciences Institute 4676 Admiralty Way Marina del Rey, California 90291 phone: (213) 822-1511 ARPANET mail: POSTEL@ISIF Most of the protocols mentioned here are documented in the RFC series of notes. The more prominent and more generally used are documented in the Protocol Handbook [17] prepared by the Network Information Center (NIC). Some of the items listed are undocumented. In all cases the name and mailbox of the responsible individual is indicated. In the lists that follow, a bracketed entry, e.g., [17,iii], at the right hand margin of the page indicates a reference for the listed protocol, where the number cites the document and the "iii" cites the person. Postel [Page 1] RFC 790 September 1981 Assigned Numbers Network Numbers ASSIGNED NETWORK NUMBERS This list of network numbers is used in the internet address [33]. The Internet Protocol (IP) uses a 32 bit address and divides that address into a network part and a "rest" or local address part. The division takes 3 forms or classes. The first type, or class a, of address has a 7-bit network number and a 24-bit local address. This allows 128 class a networks. 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| NETWORK | Local Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Class A Address The second type, or class b, of address has a 14-bit network number and a 16-bit local address. This allows 16,384 class b networks. 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1 0| NETWORK | Local Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Class B Address The third type, or class c, of address has a 21-bit network number and a 8-bit local address. This allows 2,097,152 class c networks. 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1 1 0| NETWORK | Local Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Class C Address One notation for internet host addresses commonly used divides the 32-bit address into four 8-bit fields and specifies the value of each field as a decimal number with the fields separated by periods. For example, the internet address of ISIF is 010.020.000.052. This notation will be used in the listing of assigned network Postel [Page 2] RFC 790 September 1981 Assigned Numbers Network Numbers numbers. The class a networks will have nnn.rrr.rrr.rrr, the class b networks will have nnn.nnn.rrr.rrr, and the class c networks will have nnn.nnn.nnn.rrr, where nnn represents part or all of a network number and rrr represents part or all of a local address or rest field. Assigned Network Numbers Class A Networks Internet Address Name Network References ---------------- ---- ------- ---------- 000.rrr.rrr.rrr Reserved [JBP] 001.rrr.rrr.rrr BBN-PR BBN Packet Radio Network [DCA2]Show full document text