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/rfc2173.txt | 339 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 339 insertions(+) create mode 100644 doc/rfc/rfc2173.txt (limited to 'doc/rfc/rfc2173.txt') diff --git a/doc/rfc/rfc2173.txt b/doc/rfc/rfc2173.txt new file mode 100644 index 0000000..87e021b --- /dev/null +++ b/doc/rfc/rfc2173.txt @@ -0,0 +1,339 @@ + + + + + + +Network Working Group K. Murakami +Request for Comments: 2173 M. Maruyama +Category: Informational NTT Laboratories + June 1997 + + + A MAPOS version 1 Extension - Node Switch Protocol + +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. + +Abstract + + This document describes a MAPOS extension, Node Switch Protocol, for + automatic node address assignment. MAPOS is a multiple access + protocol for transmission of network-protocol datagrams, encapsulated + in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP + automates the HDLC address configuration of each node. Using NSP, a + node retrieves its HDLC address from the switch to which it is + connected. + +1. Introduction + + MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical + Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a + protocol for transmission of HDLC frames over SONET/SDH. A SONET + switch provides multiple access capability to each node. In MAPOS, + each node has a unique HDLC address within a switch. The address is + equivalent to the port number of the switch to which the node is + connected. This document describes an extension to MAPOS, Node + Switch Protocol, which enable automatic HDLC address assignment. + First, it explains the addressing of MAPOS. Then, it describes the + NSP protocol for automatic HDLC node address assignment. + +2. Node Address Format + + This section describes MAPOS Version 1 address format in single and + multiple switch environment. + + + + + + + + + + +Murakami & Maruyama Informational [Page 1] + +RFC 2173 MAPOS June 1997 + + +2.1 Address Format + + In MAPOS network, each end node has a unique HDLC address. As shown + in Figure 1, the address length is 8 bits. The LSB is always 1 which + indicates the end of the field. When a SONET switch receives an HDLC + frame, it forwards the frame based on the address in the frame + header. + + In unicast, MSB is 0 and the rest of the bits are the port number to + which a node is connected. Since the LSB is always 1, the minimum and + maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is + reserved and is assigned to the control processor in a SONET switch. + + In broadcast, MSB is 1 and the rest of the bits are all 1s. In + multicast, MSB is 1 and the rest of the bits, except for the LSB, + indicate the group address. + + +-------------+-+ + | | | | | | | | | + | |port number|1| + +-+-----------+-+ + ^ ^ + | | + | +------- EA bit (always 1) + | + 1 : broadcast, multicast + 0 : unicast + + Figure 1 Address format + +2.2 Address in multi-switch environment + + In a multi-switch environment, variable-length subnet addressing is + used. Each switch has a switch number that is unique within the + system. Subnetted node addresses consist of the switch number and the + port number to which a node is connected. The address format is "0 + 1" for a unicast address, "all 1" for + the broadcast address, and "1 1" for a multicast + address. + + The address 0x01 is reserved and is assigned to the control processor + in the "local" switch. That is, it indicates the switch itself to + which the node is connected. The addresses of the form "0 1" are reserved, and indicates the control processor + of the switch designated by the switch number. + + In Figure 2, the switch numbers are two bits long. Node N1 is + connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus, + + + +Murakami & Maruyama Informational [Page 2] + +RFC 2173 MAPOS June 1997 + + + the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3 + has an address 01001001(0x49), since the switch number of S2 is 0x2 + (10 in binary) and the port number is 0x09. Note that all the port + numbers are odd because the LSBs are always 1. + + +------+ + | node | + | N1 | + +------+ + | 00100011(0x23) + | + |0x3 |0x3 + +------+ +---+----+ +---+----+ +------+ + | node +----+ SONET +-------+ SONET +-----+ node | + | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 | + +------+ | S1 | | S2 | +------+ + 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49) + +---+----+ +---+----+ + |0x7 |0x7 + + + Figure 2 Addressing in Multiple Switch Environment + +4 NSP(Node-Switch Protocol) + + This section describes the NSP protocol used for automatic node + address assignment. + +4.1 NSP protocol + + NSP is introduced to provide an automatic node address assignment + function in MAPOS version 1. It reduces the administrative overhead + of node address configuration for each node and prevents troubles + such as address inconsistency and collision. When a node is connected + to a switch and receives SONET signal correctly, the node sends an + address request packet to the control processor in the local switch. + The destination address of this packet is 00000001(0x01). When the + control processor receives the packet, it replies with an address + assignment packet. The destination is the assigned node address. If + the node does not receive the address assignment packet within 5 + seconds, it retransmits the address request packet. The + retransmission continues until the node successfully receives the + address assignment packet. + + Whenever a node detects a transmission error such as carrier loss or + out-of-synchronization, it SHOULD send an address request packet to + the control processor and verify its current address. In addition, a + node MUST verify its address by sending address request packets every + + + +Murakami & Maruyama Informational [Page 3] + +RFC 2173 MAPOS June 1997 + + + 30 seconds. The switch regards them as keep-alive packets and + utilizes them to detect the node's status. If it has not received a + request packet for more than 90 seconds, it assumes that the node + went down. In addition, it also assumes the node went down when a + switch detects a SONET signal failure. + +4.2 Packet Format + + The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal) + as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The + information field contains the NSP packet as shown in Figure 3. + + + +-----------+------------+ + I command I address I + +-----------+------------+ + I<- 32bit ->I<- 32 bit ->I + + Figure 3 NSP packet format + + The command field is 32 bits long and has the following values (in + decimal); + + 1 address request + 2 address assignment + 3 reject(error) + + The length of the address field is 32bits. In address request + packets, the NSP address field SHOULD be filled with zeroes, although + the switch ignores it. In address assignment packets, the assigned + address is placed in the least significant byte of the field. The + rest of the field is padded with zeroes. When the switch can not + assign the address for some reason, the switch replies with a reject + command (the values is 3). The value of the address field is + undefined. + +4.3 Consideration for special cases + + There are two special cases to consider. One is a point-to-point + connection without a switch. The other is loop-back, that is, direct + connection between the input and the output of the same port. + +4.3.1 point-to-point + + In the case of a point-to-point connection shown in Figure 4, a node + sends an address request packet to the other node. The destination + address is 00000001(0x01), that is usually a control processor in a + switch. When a node receives the address request, it detects the + + + +Murakami & Maruyama Informational [Page 4] + +RFC 2173 MAPOS June 1997 + + + point-to-point connection by examining both the destination address + and the command contained. Then, it MUST reply with an address + assignment packet. The assigned address MUST be 00000011(0x03). Since + both nodes send an address request to each other, both of them get + address 00000011(0x03). Since any address can be used in point-to- + point environment, there is no problem even if both of the nodes have + the same address. + + ---- address request ----> 0x01 + 0x03 <---- address assignment ---- + +------+ +------+ + | node +--------------------------------+ node | + +------+ +------+ + 0x01 <---- address request ---- + ---- address assignment ----> 0x03 + + Figure 4 Point-to-point connection + +4.3.2 loop-back + + Another special case is loop-back where the output port of a node is + simply connected to its input port as shown in Figure 5. In this + case, the same mechanism as that for point-to-point can be applied + without modification. A node sends an address request packet + destined to 00000001(0x01). The node then receives the same packet. + Since the destination is 00000001(0x01), it replies with an address + assignment packet, containing the assigned address 00000011(0x03), to + the address 0000 0011(0x03). Thus, the node obtains the address + 00000011(0x03). + + ---- address request ----> 0x01 + +------+ --- address assignment --> 0x03 + | +-------------->-----------------+ + | node + | + | +--------------<-----------------+ + +------+ + + Figure 5 Loop-back Configuration + + + + + + + + + + + + + +Murakami & Maruyama Informational [Page 5] + +RFC 2173 MAPOS June 1997 + + +5. Security Considerations + + Security issues are not discussed in this memo. + +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] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned + Numbers," RFC-2172, 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. + +Authors' Address + + Ken Murakami + NTT Software Laboratories + 3-9-11, Midori-cho + Musashino-shi + Tokyo 180, Japan + E-mail: murakami@ntt-20.ecl.net + + Mitsuru Maruyama + NTT Software Laboratories + 3-9-11, Midori-cho + Musashino-shi + Tokyo 180, Japan + E-mail: mitsuru@ntt-20.ecl.net + + + + + +Murakami & Maruyama Informational [Page 6] + -- cgit v1.2.3