From 4bfd864f10b68b71482b35c818559068ef8d5797 Mon Sep 17 00:00:00 2001 From: Thomas Voss Date: Wed, 27 Nov 2024 20:54:24 +0100 Subject: doc: Add RFC documents --- doc/rfc/rfc796.txt | 406 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 406 insertions(+) create mode 100644 doc/rfc/rfc796.txt (limited to 'doc/rfc/rfc796.txt') diff --git a/doc/rfc/rfc796.txt b/doc/rfc/rfc796.txt new file mode 100644 index 0000000..2ca8f1d --- /dev/null +++ b/doc/rfc/rfc796.txt @@ -0,0 +1,406 @@ + + +Network Working Group J. Postel +Request for Comments: 796 ISI +Replaces: IEN 115 September 1981 + ADDRESS MAPPINGS + ---------------- + + +Internet Addresses +------------------ + + This memo describes the relationship between address fields used in + the Internet Protocol (IP) [1] and several specific networks. + + An internet address is a 32 bit quantity, with several codings as + shown below. + + The first type (or class a) of address has a 7-bit network number and + a 24-bit local address. + + 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. + + 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. + + 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 + + The local address carries information to address a host in the + network identified by the network number. Since each network has a + + + +Postel [Page 1] + + + September 1981 +RFC 796 Address Mappings + + + + particular address format and length, the following section describes + the mapping between internet local addresses and the actual address + format used in the particular network. + +Internet to Local Net Address Mappings +-------------------------------------- + + The following transformations are used to convert internet addresses + to local net addresses and vice versa: + + AUTODIN II + ---------- + + The AUTODIN II has 16 bit subscriber addresses which identify + either a host or a terminal. These addresses may be assigned + independent of location. The 16 bit AUTODIN II address is + located in the 24 bit internet local address as shown below. + + The network number of the AUTODIN II is 26 (Class A). + + +----------------+ + | HOST/TERMINAL | AUTODIN II + +----------------+ + 16 + + +--------+--------+--------+--------+ + | 26 | ZERO | HOST/TERMINAL | IP + +--------+--------+--------+--------+ + 8 8 16 + + + + + + + + + + + + + + + + + + + + + +Postel [Page 2] + + + September 1981 +RFC 796 Address Mappings + + + + ARPANET + ------- + + The ARPANET (with 96 bit leaders) has 24 bit addresses. The 24 + bits are assigned to host, logical host, and IMP leader fields + as illustrated below. These 24 bit addresses are used directly + for the 24 bit local address of the internet address. However, + the ARPANET IMPs do not yet support this form of logical + addressing so the logical host field is set to zero in the + leader. + + The network number of the ARPANET is 10 (Class A). + + +--------+--------+--------+ + | HOST | ZERO | IMP | ARPANET + +--------+--------+--------+ + 8 8 8 + + +--------+--------+--------+--------+ + | 10 | HOST | LH | IMP | IP + +--------+--------+--------+--------+ + 8 8 8 8 + + DCNs + ---- + + The Distributed Computing Networks (DCNs) at COMSAT and UCL use + 16 bit addresses divided into an 8 bit host identifier (HID), + and an 8 bit process identifier (PID). The format locates + these 16 bits in the low order 16 bits of the 24 bit internet + address, as shown below. + + The network number of the COMSAT-DCN is 29 (Class A), and of + the UCL-DCN is 30 (Class A). + + +--------+--------+ + | HID | PID | DCN + +--------+--------+ + 8 8 + + +--------+--------+--------+--------+ + | 18 | ZERO | HID | PID | IP + +--------+--------+--------+--------+ + 8 8 8 8 + + + + + + +Postel [Page 3] + + + September 1981 +RFC 796 Address Mappings + + + + EDN + --- + + The Experimental Data Network at the Defense Communication + Engineering Center (DCEC) uses the same type of addresses as + the ARPANET (with 96 bit leaders) and has 24 bit addresses. + The 24 bits are assigned to host, logical host, and IMP leader + fields as illustrated below. These 24 bit addresses are used + directly for the 24 bit local address of the internet address. + However, the IMPs do not yet support this form of logical + addressing so the logical host field is set to zero in the + leader. + + The network number of the EDN is 21 (Class A). + + +--------+--------+--------+ + | HOST | ZERO | IMP | EDN + +--------+--------+--------+ + 8 8 8 + + +--------+--------+--------+--------+ + | 21 | HOST | LH | IMP | IP + +--------+--------+--------+--------+ + 8 8 8 8 + + LCSNET + ------ + + The LCS NET at MIT's Laboratory for Computer Science uses 32 + bit addresses of several formats. Please see [3] for more + details. The most common format locates the low order 24 bits + of the 32 bit LCS NET address in the 24 bit internet local + address, as shown below. + + The network number of the LCS NET is 18 (Class A). + + +--------+--------+--------+ + | SUBNET |RESERVED| HOST | LCSNET + +--------+--------+--------+ + 8 8 8 + + +--------+--------+--------+--------+ + | 18 | SUBNET |RESERVED| HOST | IP + +--------+--------+--------+--------+ + 8 8 8 8 + + + + + +Postel [Page 4] + + + September 1981 +RFC 796 Address Mappings + + + + PRNET + ----- + + The Packet Radio networks use 16 bit addresses. These are + independent of location (indeed the hosts may be mobile). The + 16 bit PRNET addresses are located in the 24 bit internet local + address as shown below. + + The network numbers of the PRNETs are: + + BBN-PR 1 (Class A) + SF-PR-1 2 (Class A) + SILL-PR 5 (Class A) + SF-PR-2 6 (Class A) + BRAGG-PR 9 (Class A) + DC-PR 20 (Class A) + + +--------+--------+ + | HOST | PRNET + +--------+--------+ + 16 + + +--------+--------+--------+--------+ + | net | ZERO | HOST | IP + +--------+--------+--------+--------+ + 8 8 16 + + + + + + + + + + + + + + + + + + + + + + + + +Postel [Page 5] + + + September 1981 +RFC 796 Address Mappings + + + + SATNET + ------ + + The Atlantic Satellite Packet Network has 16 bit addresses for + hosts. These addresses may be assigned independent of location + (i.e., ground station). It is also possible to assign several + addresses to one physical host, so the addresses are logical + addresses. The 16 bit SATNET address is located in the 24 bit + internet local address as shown below. + + The network number of the SATNET is 4 (Class A). + + +--------+--------+ + | HOST | SATNET + +--------+--------+ + 16 + + +--------+--------+--------+--------+ + | 4 | ZERO | HOST | IP + +--------+--------+--------+--------+ + 8 8 16 + + WBCNET + ------ + + The Wideband Communication Satellite Packet Network (WBCNET) + Host Access Protocol (HAP) has 16 bit addresses for hosts. It + is possible to assign several addresses to one physical host, + so the addresses are logical addresses. The 16 bit WBCNET + address is divided into a HAP Number field and a Local Address + field, and is located in the 24 bit internet local address as + shown below. Please see [2] for more details. + + The network number of the WBCNET is 28 (Class A). + + +--------+--------+ + | HAP NUM| LCL ADD| WBCNET + +--------+--------+ + 8 8 + + +--------+--------+--------+--------+ + | 28 | HAP NUM| ZERO | LCL ADD| IP + +--------+--------+--------+--------+ + 8 8 8 8 + + + + + + +Postel [Page 6] + + + September 1981 +RFC 796 Address Mappings + + + +References +---------- + + [1] Postel, J. (ed.), "Internet Protocol - DARPA Internet Program + Protocol Specification," RFC 791, USC/Information Sciences + Institute, September 1981. + + [2] Pershing J., "Addressing Revisited," Bolt Beranek and Newman + Inc., W Note 27, May 1981. + + [3] Noel Chiappa, David Clark, David Reed, "LCS Net Address + Format," M.I.T. Laboratory for Computer Science Network + Implementation, Note No.5, IEN 82, February 1979. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +Postel [Page 7] + -- cgit v1.2.3