RFC 1418

SNMP over OSI 💖

• Network Working Group 🌸
• RFC: 1418
• Author: Marshall T. Rose, Dover Beach Consulting, Inc. 🎀
• Date: March 1993 📅
• Category: IAB standards track protocol 👑
• Obsoletes: RFC 1161 and RFC 1283 💅
• Updates: nothing listed in the header 🧚

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Status of This Memo 📜

okay so this RFC specifies an IAB standards track protocol for the whole Internet community 🌐, and it's literally asking for discussion and suggestions for improvements 🫶. For the standardization state and status of this protocol, check the current edition of the "IAB Official Protocol Standards" 📚. And distribution of this memo is unlimited, so share away 💌.

Table of Contents 🦋

1. Background .................................................    1
2. Mapping onto the CLTS ......................................    2
2.1 Well-known Addresses ......................................    2
2.2 Traps .....................................................    2
2.3 Maximum Message Size ......................................    3
3. Acknowledgements ...........................................    3
4. References .................................................    3
5. Security Considerations ....................................    4
6. Author's Address ...........................................    4

1. Background 🌈

bestie, SNMP (as defined in [1]) is now an integral part of the network management framework for TCP/IP-based internets, and it's giving main character energy ✨. Its companion standards are the Structure of Management Information (SMI) [2,3] and the Management Information Base (MIB) [4]. Together they've gotten widespread deployment across many operational networks running the Internet suite of protocols 💜.

It should not be surprising that lots of these sites might pick up OSI capabilities and want to leverage their SNMP investment to manage those OSI components 👀. So this memo steps in and defines a framework for running SNMP in an environment that supports the OSI connectionless-mode transport service 🫶.

However, as noted in [5], the preferred mapping for SNMP is onto UDP [6] 🍓. This specification is meant for environments where UDP transport is not available. No part of this spec should be read as suggesting that, in a heterogeneous transport environment, a managed agent should support more than one mapping 🙈.

2. Mapping onto the CLTS 🎀

Mapping SNMP onto the CLTS [7,8] is super straightforward 💅. The elements of procedure are identical to using UDP. Both the CLTS and the service UDP offers transmit packets that contain full addressing information. So when you map SNMP onto the CLTS, a "transport address" in the context of [1] is simply a transport-selector and a network address 🧚.

It should be noted that mapping SNMP onto a connectionless-mode transport service is totally consistent with SNMP's architectural principles, as described in [1,5] ✨. The CLTS itself can be realized using either a connectionless-mode or a connection-oriented network service, and the mapping described here allows for either realization 🦋. (When both network services are available, the CLNS should be used as the basis of realization.) 💖

2.1. Well-known Addresses 🌸

Unlike the Internet suite of protocols, OSI does not use well-known ports 🙃. Instead, demultiplexing happens on the basis of "selectors," which are opaque strings of octets with local significance. To foster interoperable implementations of SNMP over the CLTS, it's necessary to define four selectors for this purpose 🔥.

When the CLTS provides the transport backing for SNMP and the CLTS uses a connectionless-mode network service, the transport selector used shall be snmp-l, which consists of six ASCII characters 💜. By convention, SNMP traps are sent to an SNMP manager listening on the transport selector snmpt-l, which consists of seven ASCII characters 🌈.

When the CLTS provides the transport backing for SNMP and the CLTS uses a connection-oriented network service, the transport selector used shall be snmp-o, which consists of six ASCII characters 🍓. By convention, SNMP traps are sent to an SNMP manager listening on the transport selector snmpt-o, which consists of seven ASCII characters 🫶.

2.2. Traps 👑

When SNMP traps are sent over the CLTS, the agent-addr field in the Trap-PDU contains the IP-address 0.0.0.0 🙈. An SNMP manager may figure out where the trap came from using info the transport service provides (i.e., from the T-UNIT-DATA.INDICATION primitive) 🕵️‍♀️.

2.3. Maximum Message Size 🧁

An entity implementing SNMP over OSI must be prepared to accept messages whose size is at least 484 octets 💅. Implementing larger values is encouraged whenever possible 🌟.

3. Acknowledgements 🫶

This specification was derived from RFC 1283, based on discussions in the IETF's "SNMP in a Multi-Protocol Internet" working group 💕.

4. References 📚

[1] Case, J., Fedor, M., Schoffstall, M., and J. Davin, "Simple Network Management Protocol", STD 15, RFC 1157, SNMP Research, Performance Systems International, Performance Systems International, MIT Laboratory for Computer Science, May 1990.

[2] Rose M., and K. McCloghrie, "Structure and Identification of Management Information for TCP/IP-based internets", STD 16, RFC 1155, Performance Systems International, Hughes LAN Systems, May 1990.

[3] Rose, M., and K. McCloghrie, Editors, "Concise MIB Definitions", STD 16, RFC 1212, Performance Systems International, Hughes LAN Systems, March 1991.

[4] Rose M., and K. McCloghrie, Editors, "Management Information Base for Network Management of TCP/IP-based Internets", STD 17, RFC 1213, Hughes LAN Systems, Inc., Performance Systems International, March 1991.

[5] Kastenholz, F., "SNMP Communications Services", RFC 1270, Clearpoint Research Corporation, October 1991.

[6] Postel J., "User Datagram Protocol", STD 6, RFC 768, USC/Information Sciences Institute, August 1980.

[7] Information processing systems - Open Systems Interconnection - Transport Service Definition - Addendum 1: Connectionless-mode Transmission, International Organization for Standardization. International Standard 8072/AD 1, June 1986.

[8] Information processing systems - Open Systems Interconnection - Protocol Specification for Providing the Connectionless-mode Transport Service, International Organization for Standardization. International Standard 8602, December 1987.

5. Security Considerations 💀

Security issues are not discussed in this memo. 💀 Not a single word, bestie, so they're simply not covered here 😭.

6. Author's Address 🖋️

Marshall T. Rose Dover Beach Consulting, Inc. 420 Whisman Court Mountain View, CA 94043-2112

Phone: (415) 968-1052 EMail: mrose@dbc.mtview.ca.us