SNMP-DPI: Simple Network Management Protocol Distributed Program Interface (RFC1228)
Original Publication Date: 1991-May-01
Included in the Prior Art Database: 2000-Sep-12
Internet Society Requests For Comment (RFCs)
G. Carpenter: AUTHOR [+2]
The Simple Network Management Protocol (SNMP)  Distributed Program Interface (DPI) is an extension to SNMP agents that permits end-users to dynamically add, delete or replace management variables in the local Management Information Base without requiring recompilation of the SNMP agent. This is achieved by writing a so-called sub-agent that communicates with the agent via the SNMP-DPI.
Network Working Group G. Carpenter
Request for Comments: 1228 B. Wijnen
T.J. Watson Research Center, IBM Corp.
Simple Network Management Protocol
Distributed Program Interface
Status of this Memo
This RFC describes a protocol that International Business Machines
Corporation (IBM) has been implementing in most of its SNMP agents to
allow dynamic extension of supported MIBs. This is an Experimental
Protocol for the Internet community. Discussion and suggestions for
improvement are requested. Please refer to the current edition of
the "IAB Official Protocol Standards" for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
The Simple Network Management Protocol (SNMP)  Distributed Program
Interface (DPI) is an extension to SNMP agents that permits end-users
to dynamically add, delete or replace management variables in the
local Management Information Base without requiring recompilation of
the SNMP agent. This is achieved by writing a so-called sub-agent
that communicates with the agent via the SNMP-DPI.
For the author of a sub-agent, the SNMP-DPI eliminates the need to
know the details of ASN.1  or SNMP PDU (Protocol Data Unit)
encoding/decoding [1, 3].
This protocol has been in use within IBM since 1989 and is included
in the SNMP agents for VM, MVS and OS/2.
Potentially useful sample sub-agent code and implementation examples
are available for anonymous FTP from the University of Toronto.
The Simple Network Management Protocol  defines a protocol that
permits operations on a collection of variables. This set of
variables is called the Management Information Base (MIB) and a core
set of variables has previously been defined [4, 5]; however, the
design of the MIB makes provision for extension of this core set.
Thus, an enterprise or individual can define variables of their own
which represent information of use to them. An example of a
potentially interesting variable which is not in the core MIB would
be CPU utilization (percent busy). Unfortunately, conventional SNMP
agent implementations provide no means for an end-user to make
available new variables.
The SNMP DPI addresses this issue by providing a light-weight
mechanism by which a process can register the existence of a MIB
variable with the SNMP agent. When requests for the variable are
received by the SNMP agent, it will pass the query on to the process
acting as a sub-agent. This sub-agent then returns an appropriate
answer to the SNMP agent. The SNMP agent eventually packages an SNMP
response packet and sends the answer back to the remote network
management station that initiated th...