SNMP vs. CMIP: What's the difference?

SNMP vs. CMIP: Different goals

SNMP and CMIP reflect the differing development philosophies of the internet and OSI communities. The internet community deemed simplicity as most important, especially in the early days when devices had limited memory and processor capacity. The OSI community, however, believed each protocol must be designed to be extremely flexible and to initially address future requirements.

When SNMP and CMIP were being developed in the 1980s -- and continuing into the 1990s -- individuals in the two communities felt they were in competition. Many in the OSI organizations believed internet protocols, like SNMP, would collapse under load, while internet developers often felt OSI's protocols were too complicated, difficult to implement and expensive in terms of memory and processor resources.

SNMP

The goal of SNMP developers was to provide a simple but useful protocol. SNMP initially had just two commands: GET and SET. SNMP managers use these two commands to access and modify device parameters.

SNMP and CMIP reflect the differing development philosophies of the internet and OSI communities.

The application-layer protocol initially had no security, but developers added security in later revisions. Developers also designed additional commands -- such as GETBULK and RESPONSE -- to access more than one parameter at a time and for a device to signal the SNMP manager that a problem had occurred.

The exchange between management stations and managed devices is simple. They simply exchange datagrams that contain commands and responses. No connection between manager and device is maintained with SNMP.

CMIP

OSI developers believed a more flexible and comprehensive management protocol was needed. In addition to retrieving and modifying network parameters, a CMIP manager can direct a remote application to create or delete a software entity that can then be managed.

CMIP management stations maintain connections to devices using the Remote Operations Service Element (ROSE) protocol to communicate with devices. ROSE is the OSI remote procedure call protocol, and it is used to carry CMIP commands between management stations and managed devices. All parameters are encoded using Abstract Syntax Notation One. Security features protect configurations from modification by hackers.

Although the OSI protocols are used for some applications today, the success of the internet has proven that the internet protocols -- including SNMP -- are able to carry today's traffic, a load far beyond anything imaginable in the 1980s and 1990s.