RFC 755 HISTORIC STANDARDS · NUMBERS REGISTRY · NETWORK PROTOCOLS
Assigned numbers
Updated registry of assigned numbers for network protocols in 1979
RFC EDITOR
Postel, J., "Assigned numbers", RFC 755, DOI 10.17487/RFC0755, May 1979, <https://www.rfc-editor.org/info/rfc755>.
BIBTEX
@misc{rfc755,
series = {Request for Comments},
number = 755,
howpublished = {RFC 755},
publisher = {RFC Editor},
doi = {10.17487/RFC0755},
url = {https://www.rfc-editor.org/info/rfc755},
author = {J. Postel},
title = {{Assigned numbers}},
pagetotal = 12,
year = 1979,
month = may,
} LINEAGE · FROM THE RFC INDEXOpen full graph →
RFC text
Network Working Group J. Postel
Request for Comments: 755 USC-ISI
IEN: 93 3 May 1979
Obsoletes: 750,
739, 604, 503, 433, 349
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, etc. 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@ISIB
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 [1] prepared by the Network Information Center (NIC).
In the lists that follow a bracketed number, e.g. [1], off to the right
of the page indicates a reference for the listed protocol.
IEN 93 Assigned Numbers
Link Numbers
ASSIGNED LINK NUMBERS
The word "link" here refers to a field in the original ARPANET
Host/IMP interface leader. The link was originally defined as an 8
bit field. Some time after the ARPANET Host-to-Host (AHHP) protocol
was defined and, by now, some time ago the definition of this field
was changed to "Message-ID" and the length to 12 bits. The name link
now refers to the high order 8 bits of this 12 bit message-id field.
The low order 4 bits of the message-id field are to be zero unless
specifically specified otherwise for the particular protocol used on
that link. The Host/IMP interface is defined in BBN report 1822 [2].
Link Assignments:
Decimal Octal Description References
------- ----- ----------- ----------
0 0 AHHP Control Messages [1,3]
1 1 Reserved
2-71 2-107 AHHP Regular Messages [1,3]
72-151 110-227 Reserved
152 230 PARC Universal Protocol
153 231 TIP Status Reporting
154 232 TIP Accounting
155-158 233-236 Internet Protocol [35,36,42,43,44]
159-191 237-277 Measurements [28]
192-195 300-303 Message Switching Protocol [4,5]
196-255 304-377 Experimental Protocols
224-255 340-377 NVP [1,39]
IEN 93 Assigned Numbers
Socket Numbers
ASSIGNED SOCKET NUMBERS
Sockets are used in the AHHP [1,3] to name the ends of logical
connections which carry long term conversations. For the purpose of
providing services to all callers an Initial Connection Procedure ICP
[1,34] is used between the user process and the server process. This
list specifies the socket used by the server process as its contact
socket.
Socket Assignments:
General Assignments:
Decimal Octal Description
------- ----- -----------
0-63 0-77 Network Wide Standard Function
64-127 100-177 Hosts Specific Functions
128-223 200-337 Reserved for Future Use
224-255 340-377 Any Experimental Function
Specific Assignments:
Network Standard Functions
Decimal Octal Description References
------- ----- ----------- ----------
1 1 Old Telnet [6]
3 3 Old File Transfer [7,8,9]
5 5 Remote Job Entry [1,10]
7 7 Echo [11]
9 11 Discard [12]
11 13 Who is on or SYSTAT
13 15 Date and Time
15 17 Who is up or NETSTAT
17 21 Short Text Message
19 23 Character generator or TTYTST [13]
21 25 New File Transfer [1,14,15]
23 27 New Telnet [1,16,17]
25 31 Distributed Programming System [18,19]
27 33 NSW User System w/COMPASS FE [20]
29 35 MSG-3 ICP [21]
31 37 MSG-3 Authentication [21]
33 41 DPS ICP [18,19]
35 43 IO Station Spooler
37 45 Time Server [1,22]
39 47 NSW User System w/SRI FE [20]
IEN 93 Assigned Numbers
Socket Numbers
41 51 Graphics [1,26]
42-63 52-77 unassigned
Host Specific Functions
Decimal Octal Description References
------- ----- ----------- ----------
65 101 Speech Data Base at LL-TX-2 [23]
67 103 Datacomputer at CCA [24]
69 105 CPYNET
71 107 NETRJS (EBCDIC) at UCLA-CCN [1,25]
73 111 NETRJS (ASCII-68) at UCLA-CCN [1,25]
75 113 NETRJS (ASCII-63) at UCLA-CCN [1,25]
77 115 any private RJE server
79 117 Name or Finger [1,40]
81 121 Network BSYS
83 123 MIT ML Device
85 125 MIT ML Device
86-94 126-136 unassigned
95 137 SUPDUP [33]
97 141 Datacomputer Status
98-127 142-136 unassigned
Reserved for Future Use
Decimal Octal Description References
------- ----- ----------- ----------
128-223 200-337 reserved
Experimental Functions
Decimal Octal Description References
------- ----- ----------- ----------
224-231 340-347 unassigned
232-237 350-355 Authorized Mailer at BBN
239 357 unassigned
241 361 NCP Measurement [27,28]
243 363 Survey Measurement [28,29,30]
245 365 LINK [31]
247 367 TIPSRV
249-255 371-377 RSEXEC [31,32]
IEN 93 Assigned Numbers
Network Numbers
ASSIGNED NETWORK NUMBERS
This list of network numbers is used in the internetwork protocols
now under development, the field is 8 bits in size.
Assigned Network Numbers
Decimal Octal Name Network References
------- ----- ---- ------- ----------
0 0 Reserved
1 1 BBN-PR BBN Packet Radio Network
2 2 SF-PR-1 SF Bay Area Packet Radio Network (1)
3 3 BBN-RCC BBN RCC Network
4 4 SATNET Atlantic Satellite Network
5 5 SILL-PR Ft. Sill Packet Radio Network
6 6 SF-PR-2 SF Bay Area Packet Radio Network (2)
7 7 CHAOS CHAOS Network
8 10 BBN-SAT-TEST BBN SATNET Test Network
9 11 BRAGG-PR Ft. Bragg Packet Radio Network
10 12 ARPANET ARPANET [1,2]
11 13 UCLNET University College London Network
12 14 CYCLADES CYCLADES
13 15 NPLNET National Physical Laboratory
14 16 TELENET TELENET
15 17 EPSS British Post Office EPSS
16 20 DATAPAC DATAPAC
17 21 TRANSPAC TRANSPAC
18 22 LCSNET LCS Network [37,38]
19 23 TYMNET TYMNET
20 24 DC-PR Washington D.C. Packet Radio Network
21 25 EDN DCEC EDN
22 26 DIALNET DIALNET [47,48]
23 27 MITREK MITREK Cable Network
24 30 BBN-LOCAL BBN Local Network
25 31 RSRE-PPSN RSRE / PPSN
26-254 32-376 Unassigned
255 377 Reserved
IEN 93 Assigned Numbers
Internet Message Versions
ASSIGNED INTERNET MESSAGE VERSIONS
In the internetwork protocols there is a field to identify the
version of the internetwork general protocol. This field is 4 bits
in size.
Assigned Internet Message Versions
Decimal Octal Version References
------- ----- ------- ----------
0 0 March 1977 version [35]
1 1 January 1978 version [36]
2 2 February 1978 version A [42]
3 3 February 1978 version B [43]
4 4 February 1979 version 4 [44]
5-14 5-16 Unassigned
15 17 Reserved
IEN 93 Assigned Numbers
Internet Protocol Numbers
ASSIGNED INTERNET PROTOCOL NUMBERS
In the internet protocol (IN) [44] there is a field to identify the
the next level protocol. This field is 8 bits in size. This field
is called Protocol in the IN header.
Assigned Internet Protocol Numbers
Decimal Octal Protocol Numbers References
------- ----- ---------------- ----------
0 0 Reserved
1 1 raw internet datagrams [44]
2 2 TCP-3 [36]
3 3 Gateway-to-Gateway [49]
4 4 Gateway Monitoring Message [41]
5 5 TCP-3.1 [45]
6 6 TCP-4 [46]
7 7 UCL
8 10 DSP [37,38]
9 11 Secure
10 12 TCP-2 [35]
11-12 13-14 Unassigned
13 15 Pluribus
14 16 Telenet
15 17 XNET
16 20 Chaos
17 21 UDP [50]
18 22 Multiplexing [51]
19-254 23-376 Unassigned
255 377 Reserved
IEN 93 Assigned Numbers
Internet Message Types
ASSIGNED INTERNET MESSAGE TYPES
In the March 1977 internetwork protocol [35] there is a field to
identify the type of the message. This field is 4 bits in size.
Assigned Internet Message Types
Decimal Octal Type References
------- ----- ---- ----------
0 0 Raw Internet Packet
1 1 TCP-2 [35]
2 2 Secure
3 3 Gateway
4 4 Measurement
5 5 DSP [37,38]
6 6 UCL
7-12 7-14 Reserved
13 15 Pluribus
14 16 Telenet
15 17 Xnet
IEN 93 Assigned Numbers
References
REFERENCES
[1] Feinler, E. and J. Postel, eds., "ARPANET Protocol Handbook,"
NIC 7104, for the Defense Communications Agency by SRI
International, Menlo Park, California, Revised January 1978.
[2] BBN, "Specifications for the Interconnection of a Host and an
IMP," Report 1822, Bolt Beranek and Newman, Cambridge,
Massachusetts, January 1976.
[3] McKenzie,A. "Host/Host Protocol for the ARPA Network,"
NIC 8246, January 1972. Also in [1].
[4] Walden, D. " A System for Interprocess Communication in a
Resource Sharing Network," RFC 62, NIC 4962, 3 August 1970.
Also published in Communications of the ACM, volume 15,
number 4, April 1972.
[5] Bressler, B. "A Proposed Experiment with a Message Switching
Protocol," RFC 333, NIC 9926, 15 May 72.
[6] Postel, J. "Telnet Protocol," RFC 318, NIC 9348, 3 April 1972.
[7] McKenzie, A. "File Transfer Protocol," RFC 454, NIC 14333,
16 February 1973.
[8] Clements, R. "FTPSRV -- Extensions for Tenex Paged Files,"
RFC 683, NIC 32251, 3 April 1975. Also in [1].
[9] Harvey, B. "One More Try on the FTP," RFC 691, NIC 32700,
6 June 1975.
[10] Bressler, B. "Remote Job Entry Protocol," RFC 407, NIC 12112,
16 October 72. Also in [1].
[11] Postel, J. "Echo Process," RFC 347, NIC 10426, 30 May 1972.
[12] Postel, J. "Discard Process," RFC 348, NIC 10427,
30 May 1972.
[13] Postel, J. "Character Generator Process," RFC 429, NIC 13281,
12 December 1972.
[14] Neigus, N. "File Transfer Protocol," RFC 542, NIC 17759,
12 July 1973. Also in [1].
IEN 93 Assigned Numbers
References
[15] Postel, J. "Revised FTP Reply Codes," RFC 640, NIC 30843,
5 June 1974. Also in [1].
[16] McKenzie, A. "Telnet Protocol Specification," NIC 18639,
August 1973. Also in [1].
[17] McKenzie, A. "Telnet Option Specification," NIC 18640,
August 1973. Also in [1].
[18] White, J. "A High Level Framework for Network-Based Resource
Sharing," RFC 707, NIC 34263, 14 January 1976. Also in NCC
Proceedings, AFIPS, June 1976.
[19] White, J. "Elements of a Distributed Programming System,"
RFC 708, NIC 34353, 28 January 1976.
[20] COMPASS. "Semi-Annual Technical Report," CADD-7603-0411,
Massachusetts Computer Associates, 4 March 1976. Also as,
"National Software Works, Status Report No. 1,"
RADC-TR-76-276, Volume 1, September 1976. And COMPASS. "Second
Semi-Annual Report," CADD-7608-1611, Massachusetts Computer
Associates, 16 August 1976.
[21] NSW Protocol Committee, "MSG: The Interprocess Communication
Facility for the National Software Works," CADD-7612-2411,
Massachusetts Computer Associates, BBN 3237, Bolt Beranek and
Newman, Revised 24 December 1976.
[22] Harrenstien, K. "Time Server," RFC 738, NIC 42218,
31 October 1977. Also in [1].
[23] Armenti, A., D. Hall, and A. Stone. "Lincoln Speech Data
Facility," SUR Note 37, NIC 10917, 14 July 1972.
[24] CCA, "Datacomputer Version 1 User Manual," Computer
Corporation of America, August 1975.
[25] Braden, R. "NETRJS Protocol," RFC 740, NIC 42423,
22 November 1977. Also in [1].
[26] Sproull, R, and E. Thomas. "A Networks Graphics Protocol,"
NIC 24308, 16 August 1974. Also in [1].
[27] Cerf, V., "NCP Statistics," RFC 388, NIC 11360,
23 August 1972.
IEN 93 Assigned Numbers
References
[28] Cerf, V., "Formation of a Network Measurement Group (NMG),"
RFC 323, NIC 9630, 23 March 1972.
[29] Bhushan, A., "A Report on the Survey Project," RFC 530,
NIC 17375, 22 June 1973.
[30] Cantor, D., "Storing Network Survey Data at the Datacomputer,"
RFC 565, NIC 18777, 28 August 1973.
[31] Bressler, R., "Inter-Entity Communication -- An Experiment,"
RFC 441, NIC 13773, 19 January 1973.
[32] Thomas, R. "A Resource Sharing Executive for the ARPANET,"
AFIPS Conference Proceedings, 42:155-163, NCC, 1973.
[33] Crispin, M. "SUPDUP Protocol," RFC 734, NIC 41953,
7 October 1977. Also in [1].
[34] Postel, J. "Official Initial Connection Protocol," NIC 7101,
11 June 1971. Also in [1].
[35] Cerf, V. "Specification of Internet Transmission Control
Program -- TCP (version 2)," March 1977.
[36] Cerf, V. and J. Postel, "Specification of Internetwork
Transmission Control Program -- TCP Version 3,"
USC-Information Sciences Institute, January 1978.
[37] Reed, D. "Protocols for the LCS Network," Local Network Note
3, Laboratory for Computer Science, MIT, 29 November 1976.
[38] Clark, D. "Revision of DSP Specification," Local Network Note
9, Laboratory for Computer Science, MIT, 17 June 1977.
[39] Cohen, D. "Specifications for the Network Voice Protocol
(NVP)," NSC Note 68, 29 January 1976. Also as USC-Information
Sciences Institute RR-75-39, March 1976, and as RFC 741,
NIC 42444, 22 November 1977. Also in [1].
[40] Harrenstien, K. "Name/Finger," RFC 742, NIC 42758,
30 December 1977. Also in [1].
[41] Cole, J. "Gateway Monitoring Messages," BBN, 1 February 1978.
[42] Postel, J. "Draft Internetwork Protocol Specification --
Version 2," USC-Information Sciences Institute, February 1978.
IEN 93 Assigned Numbers
References
[43] Cerf, V. "A Proposed New Internet Header Format," Advanced
Research Projects Agency, IEN 26, 14 February 1978.
[44] Postel, J. "Internet Datagram Protocol -- Version 4," IEN-80,
USC-Information Sciences Institute, February 1979.
[45] Cerf, V. "A Proposal for TCP Version 3.1 Header Format,"
Advanced Research Projects Agency, IEN 26, 14 February 1978.
[46] Postel, J., "Transmission Control Protocol -- Version 4,"
IEN-81, USC-Information Sciences Institute, February 1979.
[47] McCarthy, J. and L. Earnest, "DIALNET," Stanford University
Artificial Intelligence Laboratory, Undated.
[48] Crispin, M. and I. Zabala, "DIALNET Protocols," Stanford
University Artificial Intelligence Laboratory, July 1978.
[49] Strazisar, V, and R. Perlman, "Gateway Routing, An
Implementation Specification," IEN-30, Bolt Berenak and
Newman, April 1978.
[50] Postel, J., "User Datagram Protocol," IEN-88, USC-Information
Sciences Institute, May 1979.
[51] Cohen, D. and J. Postel, "Multiplexing Protocol," IEN-90,
USC-Information Sciences Institute, May 1979.
AI ELI5
On this page
PROBLEMProtocols and network numbers continued to be assigned; the 1978 registry (RFC 750) needed updates to remain current.
MECHANISMJon Postel issued an updated assigned-numbers registry covering link numbers, socket numbers, network numbers (now with 26 assignments including DIALNET and MITREK), IP versions, and protocol formats with new entries for Gateway-to-Gateway and other protocols.
CONTINUED NUMBER MANAGEMENTThe registry continued to serve as the authoritative source for protocol numbers and assignments. It was again replaced the following year by RFC 758.
§1Maintaining the Registry
RFC 755 is the 1979 update to the assigned numbers registry. Like RFC 750, it documents all numbers assigned in ARPANET and internet protocols: link numbers, socket numbers, network addresses, protocol versions, and protocol numbers. Jon Postel continued to manage assignments and maintain the registry.
This version consolidates six earlier RFCs (750, 739, 604, 503, 433, 349) into one comprehensive list, maintaining the tradition of keeping a single authoritative source as the network and its protocols evolved.
The list was updated again a year later with new networks and protocols that had been added or discovered.
§2Updated Assignments
The network numbers section grew from 22 to 26 assignments, adding DIALNET (22), MITREK Cable Network (23), BBN Local Network (24), and RSRE/PPSN (25). Socket and link assignments remained largely the same, with some additions to the protocol format identifiers (now including Gateway-to-Gateway on protocol 3, and more internet protocols).
The IP protocol numbers section expanded to include new variants tested and deployed in the late 1970s. The socket ranges and their meanings (0–63 standard, 64–127 host-specific, 128–223 reserved, 224–255 experimental) remained consistent with the 1978 version.
More networks and protocols got added to the lists. The basic structure stayed the same, but the registries grew as the internet expanded.
§3Periodic Updates
RFC 755 notes that the registry would continue to be updated periodically, with current information always available from Jon Postel. The RFC maintains the same reference format as RFC 750, citing the Protocol Handbook and other RFCs for detailed specifications.
RFC 755 is Historic and was replaced by RFC 758 in 1980, which continued the annual or biennial update cycle. This pattern of maintained, authoritative registries eventually evolved into the modern IANA system.
This was just the latest version. Jon would keep updating it as more protocols got assigned numbers. The next year there would be another update.