MAPOS Version 1 Assigned Numbers
The registry of Protocol field values used by MAPOS version 1, a multiple-access link layer for SONET/SDH.
Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned Numbers", RFC 2172, DOI 10.17487/RFC2172, June 1997, <https://www.rfc-editor.org/info/rfc2172>.
@misc{rfc2172,
series = {Request for Comments},
number = 2172,
howpublished = {RFC 2172},
publisher = {RFC Editor},
doi = {10.17487/RFC2172},
url = {https://www.rfc-editor.org/info/rfc2172},
author = {M. Maruyama and K. Murakami},
title = {{MAPOS Version 1 Assigned Numbers}},
pagetotal = 3,
year = 1997,
month = jun,
} RFC text
Contents
Network Working Group M. Maruyama
Request for Comments: 2172 K. Murakami
Category: Informational NTT Laboratories
June 1997
MAPOS Version 1 Assigned Numbers
Status of this Memo
This memo provides information for the Internet community. This memo
does not specify an Internet standard of any kind. Distribution of
this memo is unlimited.
Authors' Note
This memo documents the parameters used in the Multiple Access
Protocol over SONET/SDH Version 1. This document is NOT the product
of an IETF working group nor is it a standards track document. It
has not necessarily benefited from the widespread and in-depth
community review that standards track documents receive.
Abstract
This document describes the protocol parameters used in the Multiple
Access Over SONET/SDH (MAPOS) version 1. MAPOS is a link layer
protocol and provides multiple access capability over SONET/SDH
links.
1. Introduction
Multiple Access Protocol over SONET/SDH (MAPOS) [1] is a high-speed
link-layer protocol that provides multiple access capability over
SONET(Synchronous Optical Network)/SDH(Synchronous Digital
Hierarchy)[2][3][4][5]. Its frame format is based on the HDLC-like
framing [6] for PPP. A component called "Frame Switch" [1] allows
multiple nodes to be connected together in a star topology to form a
LAN. Using long haul SONET/SDH links, the nodes on such a "SONET-LAN"
can span over a wide geographical area. The Internet Protocol (IP)
[7] datagrams are transmitted in MAPOS HDLC frames [8].
This document describes the protocol parameters used in MAPOS version
1 [1].
2. Protocol Field Assignments
The MAPOS Version 1 Data Link Layer [1] contains a 16 bit Protocol
field to identify the the encapsulated protocol. The Protocol field
is consistent with the ISO 3309 (HDLC) extension mechanism for
address fields. All protocol numbers MUST be assigned such that the
least significant bit of the most significant octet equals "0", and
the least significant bit of the least significant octet equals "1".
Assigned MAPOS Protocol Numbers
Value (in hex) Protocol Name
0001-001F Not Used - reserved
0021 MAPOS Version 1 Internet Protocol Version 4 [8]
0023-FCFF Not Used - reserved
FE01 MAPOS Version 1 Address Resolution Protocol (ARP[8])
FE03 MAPOS Version 1 Node Switch Protocol (NSP[9])
FE05 MAPOS Version 1 Switch Switch Protocol (SSP[10])
FE07-FEFF Not Used - reserved
References
[1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
over SONET/SDH, Version 1," RFC-2171, June 1997.
[2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
Rates (1990).
[3] CCITT Recommendation G.708: Network Node Interface for
Synchronous Digital Hierarchy (1990).
[4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
(1990).
[5] American National Standard for Telecommunications - Digital
Hierarchy - Optical Interface Rates and Formats Specification,
ANSI T1.105-1991.
[6] Simpson, W., editor, "PPP in HDLC-like Framing," RFC-1662,
July 1994.
[7] Postel, J., "Internet Protocol (IP)," RFC-791, September 1981.
[8] Murakami, K. and M. Maruyama, "IPv4 over MAPOS Version 1,"
RFC-2176, June, 1997.
[9] Murakami, K. and M. Maruyama, "A MAPOS version 1 Extension -
Node Switch Protocol," RFC-2173, June, 1997.
[10] Murakami, K. and M. Maruyama, "A MAPOS version 1 Extension -
Switch Switch Protocol," RFC-2174, June, 1997.
Acknowledgements
The authors would like to acknowledge the contributions and
thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
Author's Address
Mitsuru Maruyama
NTT Software Laboratories
3-9-11, Midori-cho
Musashino-shi
Tokyo-180, Japan
E-mail: mitsuru@ntt-20.ecl.net
Ken Murakami
NTT Software Laboratories
3-9-11, Midori-cho
Musashino-shi
Tokyo-180, Japan
E-mail: murakami@ntt-20.ecl.net
AI ELI5
On this page
§1What MAPOS Is
MAPOS (Multiple Access Protocol over SONET/SDH) is a high-speed link-layer protocol that provides multiple access over SONET/SDH links. Its frame format is based on the HDLC-like framing used for PPP. A component called a Frame Switch lets multiple nodes connect in a star topology to form a LAN, which can span a wide area over long-haul SONET/SDH links. IP datagrams are sent in MAPOS HDLC frames.
The authors' note states that this document is not the product of an IETF working group, is not standards track, and has not necessarily had the in-depth community review that standards-track documents get.
MAPOS lets many computers share a fast fiber-optic line, a bit like many houses on one street. This note is only about the numbers it uses.
§2The Protocol Field Rule
The MAPOS version 1 data link layer has a 16-bit Protocol field that identifies the encapsulated protocol. It follows the ISO 3309 (HDLC) extension mechanism for address fields. Every protocol number MUST be assigned so that the least significant bit of the most significant octet is 0 and the least significant bit of the least significant octet is 1.
There is a rule about the first and last tiny bits of every number, so receivers can tell where one number ends.
§3Assigned Protocol Numbers
The memo lists four assigned values, in hexadecimal: 0021 for IPv4 (defined in RFC 2176), FE01 for the Address Resolution Protocol, FE03 for the Node Switch Protocol (RFC 2173) and FE05 for the Switch Switch Protocol (RFC 2174). The ranges 0001-001F, 0023-FCFF and FE07-FEFF are marked as not used and reserved.
A few numbers are already taken for internet mail, address lookup, and two jobs the switches do. The rest are saved for later.
- 0001-001FReserved — Not used.
- 0021IPv4 — MAPOS Version 1 Internet Protocol Version 4.
- 0023-FCFFReserved — Not used.
- FE01ARP — MAPOS Version 1 Address Resolution Protocol.
- FE03NSP — MAPOS Version 1 Node Switch Protocol.
- FE05SSP — MAPOS Version 1 Switch Switch Protocol.
- FE07-FEFFReserved — Not used.