The TCP/IP Guide - TCP/IP MIB Modules and Object Groups

Table 208 shows the eight generic SNMP groups defined in RFC 1158 along with their codes, names and numbers.

**Table 208: SNMP Generic MIB Object Groups**
Group Name	Group Code	Group Number	Full Group Identifier	Description
*system*	*sys*	1	1.3.6.1.2.1.1	General objects of relevance to all or most devices. For example, a general description of the device is an object in this group, as is the identifier of the object. Later MIB versions greatly expanded the number of variables in this group.
*Interfaces*	if	2	1.3.6.1.2.1.2	Objects related to the IP interfaces between this device and the internetwork; recall that a regular host normally has one interface while a router has two or more.
*at (address translation)*	at	3	1.3.6.1.2.1.3	Objects used for IP address translation. (No longer used.)
ip	ip	4	1.3.6.1.2.1.4	Objects related to the IP layer of the device as a whole (as opposed to interface-specific information in the if group.)
*icmp*	*icmp*	5	1.3.6.1.2.1.5	Objects related to the operation of the Internet Control Message Protocol.
*tcp*	*tcp*	6	1.3.6.1.2.1.6	Objects related to the operation of the Transmission Control Protocol.
*udp*	*udp*	7	1.3.6.1.2.1.7	Objects related to the operation of the User Datagram Protocol.
*egp*	*egp*	8	1.3.6.1.2.1.8	Objects related to the operation of the Exterior Gateway Protocol.
*cmot*	*cmot*	9	1.3.6.1.2.1.9	Objects related to running the CMIP protocol over TCP (historical, not used.)
*transmission*	*trans*	10	1.3.6.1.2.1.10	Objects related to the specific method of information transmission used by each interface on the system.
*snmp*	*snmp*	11	1.3.6.1.2.1.11	Objects used to manage SNMP itself.

All of the groups in this table are fairly generic, and with the exception of the one about EGP, apply to pretty much every TCP/IP system using SNMP. The first five groups and the last one are “mandatory” for all systems; the others are used only by devices that use the indicated protocols or functions. The mention of EGP, a routing protocol now considered obsolete, shows the age of this list.