IPv4 over MAPOS Version 1 (RFC2176)
Original Publication Date: 1997-Jun-01
Included in the Prior Art Database: 2019-Feb-15
Internet Society Requests For Comment (RFCs)
K. Murakami: AUTHOR [+1]
This memo documents a mechanism for supporting Version 4 of the Internet Protocol (IPv4) on Version 1 of the Multiple Access Protocol over SONET/SDH. This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind.
Network Working Group K. Murakami Request for Comments: 2176 M. Maruyama Category: Informational NTT Laboratories June 1997
IPv4 over MAPOS Version 1
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.
This memo documents a mechanism for supporting Version 4 of the Internet Protocol (IPv4) on Version 1 of the Multiple Access Protocol over SONET/SDH. 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.
This document describes a protocol for transmission of the Internet Protocol Version 4 (IPv4) over Multiple Access Over SONET/SDH (MAPOS) version 1. MAPOS is a link layer protocol and provides multiple access capability over SONET/SDH links. IP runs on top of MAPOS. This document explains IP datagram encapsulation in HDLC frame of MAPOS, and the Address Resolution Protocol (ARP).
Multiple Access Protocol over SONET/SDH (MAPOS)  is a high-speed link-layer protocol that provides multiple access capability over SONET/SDH. Its frame format is based on the HDLC-like framing  for PPP. A component called "Frame Switch"  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)  datagrams are transmitted in MAPOS HDLC frames .
This document describes a protocol for transmission of IP datagrams over MAPOS version 1 . It explains IP datagram encapsulation in HDLC frame of MAPOS, and ARP (Address Resolution Protocol) for mapping between IP address and HDLC address.
Murakami & Maruyama Informational [Page 1]
RFC 2176 MAPOS June 1997
2. Frame Format for Encapsulating IP Datagrams
An IP datagram is transmitted in a MAPOS HDLC frame. The protocol field of the frame must contain the value 0x0021 (hexadecimal) as defined by the "MAPOS Version 1 Assigned Numbers" . The information field contains the IP datagram.
The information field may be one to 65,280 octets in length; the MTU(Maximum Transmission Unit) of MAPOS is 65,280 octets. Although the large MTU size can suppress the overhead of IP header processing, it may cause fragmentation anywhere along the path from the source to the destination and result in performance degradation. To cope with the issue, Path MTU discovery  may be used.
3. Address Mapping
This section explains MAPOS ARP and the mapping of special addresses.
3.1 ARP cache
Each node on a MAPOS network maintains an "ARP cache" that maps destination IP addresses to their corresponding 8-bit HDLC addresses. Entries are added to this cache either manually or by the Address Resolution Protocol described below. Entries are removed from this cache man...