Assigned Numbers
RFC 900
Document | Type |
RFC - Historic
(June 1984; No errata)
Obsoleted by RFC 923
Obsoletes RFC 870
|
|
---|---|---|---|
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 900 (Historic) | |
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group J. Reynolds
Request for Comments: 900 J. Postel
ISI
Obsoletes RFCs: 870, 820, June 1984
790, 776, 770, 762, 758, 755,
750, 739, 604, 503, 433, 349
Obsoletes IENs: 127, 117, 93
ASSIGNED NUMBERS
Status of this Memo
This memo is an official status report on the numbers used in
protocols in the ARPA-Internet community.
Introduction
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 Joyce Reynolds. The assignment of numbers is also handled by
Joyce. If you are developing a protocol or application that will
require the use of a link, socket, port, protocol, network number,
etc., please contact Joyce to receive a number assignment.
Joyce Reynolds
USC - Information Sciences Institute
4676 Admiralty Way
Marina del Rey, California 90292-6695
Phone: (213) 822-1511
ARPA mail: JKREYNOLDS@USC-ISIF.ARPA
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 "Internet Protocol Transition Workbook" [31] or in the old
"ARPANET Protocol Handbook" [32] prepared by the NIC. Some of the
items listed are undocumented. Further information on protocols can
be found in the memo "Official Protocols" [83].
In all cases the name and mailbox of the responsible individual is
indicated. In the lists that follow, a bracketed entry, e.g.,
[31,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. Whenever possible, this "iii" is a NIC
Ident.
Reynolds & Postel [Page 1]
Assigned Numbers RFC 900
Network Numbers
ASSIGNED NETWORK NUMBERS
The network numbers listed here are used as internet addresses by the
Internet Protocol (IP) [31,71]. The IP uses a 32-bit address field
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 of address, or class A, has a 7-bit network number
and a 24-bit local address. The highest-order bit is set to 0.
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 of address, class B, has a 14-bit network number
and a 16-bit local address. The two highest-order bits are set to
1-0. 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 of address, class C, has a 21-bit network number
and a 8-bit local address. The three highest-order bits are set
to 1-1-0. 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
Note: No addresses are allowed with the three highest-order bits
set to 1-1-1. These addresses (sometimes called "class D") are
reserved.
Reynolds & Postel [Page 2]
Assigned Numbers RFC 900
Network Numbers
One commonly used notation for internet host addresses 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. This
is called the "dotted decimal" notation. For example, the internet
address of USC-ISIF.ARPA in dotted decimal is 010.002.000.052, or
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