Assigned Network Numbers
An assigned-number list and header description for early internetwork experiments.
Postel, J., "Assigned Network Numbers", RFC 717, DOI 10.17487/RFC0717, July 1976, <https://www.rfc-editor.org/info/rfc717>.
@misc{rfc717,
series = {Request for Comments},
number = 717,
howpublished = {RFC 717},
publisher = {RFC Editor},
doi = {10.17487/RFC0717},
url = {https://www.rfc-editor.org/info/rfc717},
author = {J. Postel},
title = {{Assigned Network Numbers}},
pagetotal = 1,
year = 1976,
month = jul,
} RFC text
NWG/RFC# 717 JBP 30-JUN-76 16:58 35873
Assigned Network Numbers
Network Working Group Jon Postel
Request for Comments 717 SRI-ARC
NIC 35873 1 July 1976
Assigned Network Numbers
This note specifies the numbers assigned to identify networks for use in
the inter-network protocol experiments. Additional Numbers are assigned
by Jon Postel [POSTEL@ISIC or (415) 326-6200 x3718].
Assigned Network Numbers
Name Decimal Octal
---------- ------- -----
BBNRCCnet 3 3
SanFranPRnet 7 7
ARPANET 10 12
BostonPRnet 11 13
Internetwork Header Format
For convenience the current Internetwork protocol header and TCP
headers are reproduced here:
Octet Bit Use (Width)
--- Beginning of protocol-independent information ---
0 Destination net (8)
1-3 Destination host (24)
4 Source net (8)
5-7 Source host (24)
8-9 Data length in octets (16)
10 Header length in octets (8)
11 0-3 Format (4)
This field selects the appropriate gateway processing and is used
to dispatch the packet to the appropriate protocol module in the
destination. The following values are defined for this field:
0 -- Escape; protocol is specified by a subsequent field
1 -- TCP
2 -- Secure TCP
3-16 -- Not allocated
17 -- Cross internet debugging
--- End of protocol-independent information
1
NWG/RFC# 717 JBP 30-JUN-76 16:58 35873
Assigned Network Numbers
--- Beginning of TCP specific information ---
11 4-7 Protocol version (4)
12-15 Sequence number (32)
16-17 Window (16)
18-20 Control (as before) (24)
21-23 Destination port (24)
24 Packet label for debugging(8)
25-27 Source port (24)
28-31 Acknowledgement number (32)
32-33 Checksum (16)
34- Data
--- End of TCP specific information ---
--- Beginning of short TCP specific information ---
11 4-7 Protocol Version (4)
12-25 Sequence number (32)
16 Destination KID (8)
17 Source KID (8)
18-19 Control (no special function field)(16)
20- Data
--- End of short TCP specific information ---
2
ISO Plain Language
On this page
§1Assigned Network Numbers
The note lists four assignments: BBNRCCnet has decimal number 3, SanFranPRnet 7, ARPANET 10, and BostonPRnet 11. It says additional numbers are assigned by Jon Postel.
These numbers identify networks for use in the inter-network protocol experiments described by the memo.
The memo lists four networks and the numbers assigned to them for experiments. It also names the person to contact about additional assignments.
§2Internetwork Header Fields
The reproduced protocol-independent header uses 8 bits for the destination network and 24 bits for the destination host, followed by equivalent source fields. It also carries data length, header length, and a four-bit Format field.
The Format value selects gateway processing and the destination protocol module. The memo lists values for Escape, TCP, Secure TCP, and Cross Internet Debugging.
The header identifies the source and destination network and host. A format value tells the gateway which protocol processing to use.
§3TCP-Specific Header Information
The memo also reproduces a TCP-specific header containing a protocol version, sequence number, window, control field, ports, acknowledgement number, and checksum. A separate short TCP-specific layout is included.
These layouts are presented as the current headers for the inter-network protocol experiments.
The TCP-specific portion carries connection and data-transfer information, including sequence and acknowledgement numbers and port values.