Introduction | SNMP Architecture | the Protocol
Structure of Management Information | Object Identifier
Management Information Base | Common Tasks | References

Common Tasks

01. System Monitoring

The system MIB group is a very simple group consisted of seven objects numbered below as it can be found on the MIB:

OID	Name	Datatype	Writable	Description
1	sysDescr	Display String	no	Description of the monitored device
2	sysObjectID	ObjectID	no	Vendor's identification of the device. It is localized at 1.3.6.1.4.1.
3	sysUpTime	TimeTicks	no	Time since the last network management reboot in nanoseconds.
4	sysContact	Display String	yes	Information about the contact person of this node.
5	sysName	Display String	yes	Node's domain name.
6	sysLocation	Display String	yes	Location of the node.
7	sysServices	INTEGER	no	This variable indicates the OSI layers avaiable in the node. The first bit indicates the physical layer, the second indicates the datalink layer, the third is for internet, the fourth is used to end-to-end, the fifth to

The SNMP OID of the system group is 1.3.6.1.2.1.1(mib.system)

02. Interfaces Monitoring

This is a very powerful group. It has only a variable(ifNumber) and a table(ifTable). It OID is 1.3.6.1.2.1.2(mib.interfaces).

The variable ifNumber is a read-only INTEGER wich displays the number of network interfaces on a system.

The table ifTable is a list of interfaces entries (ifEntry). It has the number entries specified in ifNumbers. Each ifEntry has the following variables:

OID	Name	Datatype	Writable	Description
1	ifIndex	INTEGER	no	The index of the interface
2	ifDescr	Display String	no	The description of the interface
3	ifType	INTEGER	no	Type of the interface, like: 5(X.25), 6(Ethernet CSMA-CD), 7(802.3 Ethernet), 9(802.5 token ring), 23(PPP). Another values can be found at The Internet Task Force - Management Information Base for Network Management of TCP/IP-based internets: MIB-II
4	ifMtu	INTEGER	no	The largest IP datagram this interface can send or receive
5	ifSpeed	Gauge	no	The current bandwith of the interface in bits/sec
6	ifPhysAddress	Phys Address	no	Physical address of the interface
7	ifAdminStatus	INTEGER	yes	Desired status of the interface. It can be 1 to pass all packets, 2 to become down and 3 to enter the testing mode
8	ifOperStatus	INTEGER	no	Current status of the interface. It can be 1 to pass all packets, 2 to become down and 3 to enter the testing mode
9	ifLastChange	TimeTicks	no	Displays the value found in sysUpTime when the status of the interface changed.
10	ifInOctets	Counter	no	Total number of bytes received
11	ifInUcastPkts	Counter	no	Total number of unicast packets sent to a higher layer protocol
12	ifInNUcastPkts	Counter	no	Number of nonunicast packets sent to a higher layer protocol
13	ifInDiscards	Counter	no	Total number of discarded packets even though no error was detected
14	ifInErrors	Counter	no	Total number of received packets discarded because an error was detected
15	ifInUnknown Protos	Counter	no	Displays the total number of received packets discarded because an unknown protocol was used
16	ifOutOctets	Counter	no	Total number of sent bytes
17	ifOutUcastPkts	Counter	no	Total number of unicast packets received from a higher layer protocol
18	ifOutNUcastPkts	Counter	no	Total number of nonunicast packets received from a higher layer protocol
19	ifOutDiscards	Counter	no	Number of sent packets discarded even though no error was detected
20	ifOutErrors	Counter	no	Number of sent packets discarded due to any error was found
21	ifOutQLen	Gauge	no	Length of output packets queue
22	ifSpecific	ObjectID	no	A reference to MIB definitions specific to the particular type of media being used to realize the interface. If this interface is realized by ethernet, this object will reference to a document defining objects specific to ethernet

03. IP Monitoring

IP monitoring is an important task in network management. The ip group OID is 1.3.6.1.2.1.4(mib.ip). This group defines 20 variables and three tables. All variables are ordered in the next table by its OID.

OID	Name	Datatype	Writable	Description
1	ipForwading	INTEGER	yes	Indicates if this device is working as a gateway
2	ipDefaultTTL	INTEGER	yes	The default Time-To-Live value if the transport protocol doesn't provide one
3	ipInReceives	Counter	no	Total number of ip datagrams received
4	ipInHdrErrors	Counter	no	Number of discarded datagrams because a header error was found
5	ipInAddrErrors	Counter	no	Total number of discarded datagrams because an error in the destination address was found
6	ipForwD atagrams	Counter	no	Number of forwaded ip datagrams
7	ipInUnknown Protos	Counter	no	Number of received ip datagrams discarded due to an invalid protocol field
8	ipInDiscards	Counter	no	Total number of input IP datagrams without processing errors, but were discarded(e.g., lack of buffer space)
9	ipInDelivers	Counter	no	Number of received IP datagrams correctly delivered to the user-protocol.
10	ipOutRequests	Counter	no	Total number of sent IP datagrams. This counter don't include those counted in ipForwDatagrams
11	ipOutDiscards	Counter	no	Number of output IP datagrams discarded due to lack of buffer space
12	ipOutNoRoute	Counter	no	Total number of output IP datagrams discarded due no route could be found to transmit them to their destination
13	ipReasm Timeout	INTEGER	no	Number of seconds that received fragments are held awaiting reassembly
14	ipReasmReqds	Counter	no	Total number of received IP fragments that needed to be reassembled
15	ipReasmOKs	Counter	no	Total number of IP datagrams successfully reassembled
16	ipReasmFails	Counter	no	Total number of IP datagrams failed on the reassembly
17	ipFragOKs	Counter	no	Number of IP datagrams successfully fragmented
18	ipFragFails	Counter	no	Number of IP datagrams failed during the fragmentation
19	ipFragCreates	Counter	no	Number of IP fragments created as a result of fragmentation
23	ipRouting Discards	Counter	no	Number of discarded route entries even if no error was found

The first table is the ipAddrTable with the OID 20. It has one row for each IP address on the system. All itens of this table is listed below:

OID	Name	Datatype	Writable	Description
1	ipAdEntAddr	IpAddress	no	IP address of the current table entry
2	ipAdEntIfIndex	INTEGER	no	The interface number specified in ifIndex for this IP address
3	ipAdEnt NetMask	IpAddress	no	Associated subnet for this IP address
4	ipAdEntB castAddr	INTEGER	no	Least-significant bit in the IP broadcast
5	ipAdEntReasm MaxSize	INTEGER	no	Maximum size of the IP datagram can be reassembled

The OID 21 of the ip group is the ipRouteTable. It is a table with 13 columns and a row for each destination address inserted.

OID	Name	Datatype	Writable	Description
1	ipRouteDest	IpAddress	yes	Destination IP address of this route.
2	ipRouteIfIndex	INTEGER	yes	Corresponding interface id(ifIndex)
3	ipRouteMetric1	INTEGER	yes	Primary route metric for this route. The value depends of ipRouteProto. If it is not in use the value will be -1
4	ipRouteMetric2	INTEGER	yes	Alternative routing metric for this route
5	ipRouteMetric3	INTEGER	yes	Alternative routing metric for this route
6	ipRouteMetric4	INTEGER	yes	Alternative routing metric for this route
7	ipRouteNextHop	IpAddress	yes	The next hop of this route
8	ipRouteType	INTEGER	yes	The type of the route that can be 1 for other, 2 for invalidated route, 3 for directly route and 4 for a non-local route
9	ipRouteProto	INTEGER	no	Routing protocol for this route. Possible values are 1 to other, 2 for local, 4 to ICMP redirect. The complete possible values is in The Internet Task Force - Management Information Base for Network Management of TCP/IP-based internets: MIB-II
10	ipRouteAge	INTEGER	yes	Time in seconds since the last update of this route
11	ipRouteMask	IpAddress	yes	A mask to be ANDed with the destination IP address before being compared to the value in ipRouteDest field
12	ipRouteMetric5	INTEGER	yes	Alternative routing metric for this route
13	ipRouteInfo	ObjectID	no	OID of the reference of this routing protocol

And the last table in the ip group is the ipNetToMediaTable with the OID 22. It is used to mapping the IP address to physical address.

04. ICMP Monitoring

The icmp group has the OID 1.3.6.1.2.1.5(mib.icmp) and 26 variables: 13 for input ICMP messages and 13 for output ICMP messages. All these variables are ordered below by OID.

OID	Name	Datatype	Writable	Description
1	icmpInMsgs	Counter	no	Total number of all ICMP messages received
2	icmpInErrors	Counter	no	Number of received ICMP messages with specific ICMP errors
3	icmpInDest Unreachs	Counter	no	Total number of received ICMP unreachable messages
4	icmpIn TimeExcds	Counter	no	Number of received ICMP time exceeded messages
5	icmpIn ParmProbs	Counter	no	Number of received ICMP parameter problem messages
6	icmpInSrc Quenchs	Counter	no	Number of ICMP source quench messages received
7	icmpInRedirects	Counter	no	Total number of ICMP redirect messages received
8	icmpInEchos	Counter	no	Total number of ICMP echo request messages received
9	icmpInEchoReps	Counter	no	Total number of ICMP echo reply messages received
10	icmpIn Timestamps	Counter	no	The number of received ICMP timestamp request messages
11	icmpIn TimestampsReps	Counter	no	The number of received ICMP timestamp reply messages
12	icmpIn AddrMasks	Counter	no	Total number of ICMP address mask request messages received
13	icmpInAddr MasksReps	Counter	no	Total number of ICMP address mask reply messages received
14	icmpOutMsgs	Counter	no	Total number of all ICMP messages sent
15	icmpOutErrors	Counter	no	Number of sent ICMP messages with specific ICMP errors
16	icmpOutDest Unrechs	Counter	no	Total number of ICMP unreachable messages sent
17	icmpOut TimeExcds	Counter	no	Number of sent ICMP time exceeded messages
18	icmpOut ParmProbs	Counter	no	Number of sent ICMP parameter problem messages
19	icmpOutSrc Quenchs	Counter	no	Number of ICMP source quench messages sent
20	icmpOut Redirects	Counter	no	Total number of ICMP redirect messages sent
21	icmpOutEchos	Counter	no	Total number of ICMP echo request messages sent
22	icmpOut EchoReps	Counter	no	Total number of ICMP echo reply messages sent
23	icmpOut Timestamp	Counter	no	The number of sent ICMP timestamp request messages
24	icmpOut TimestampReps	Counter	no	The number of sent ICMP timestamp reply messages
25	icmpOut AddrMasks	Counter	no	Total number of ICMP address mask request messages received
26	icmpOutAddr MasksReps	Counter	no	Total number of ICMP address mask reply messages received

 

OID	Name	Datatype	Writable	Description
1	ipNetToMediaIfIndex	INTEGER	yes	Wich interface this entry is effective
2	ipNetToMediaPhysAddress	PhysAddress	yes	The physical address
3	ipNetToMediaNetAddress	IpAddress	yes	Corresponding IP address to the physical address
4	ipNetToMediaType	INTEGER	yes	The type of mapping. It can be 1 for other, 2 for invalidated, 3 for dynamic and 4 for static

05. TCP Monitoring

The tcp group manages information about TCP connections. It has 14 variables, a table called tcpConnTable and the OID 1.3.6.1.2.1.6(mib.tcp).

OID	Name	Datatype	Writable	Description
1	tcpRtoAlgorithm	INTEGER	no	This variable indicates the algorithm used to calculate the timeout value for retransmitting unacknowledged octets. Possible values are: 1(none of the following), 2(a constant RTO), 3(MIL-STD-1778), 4(Van Jacobson's algorithm)
2	tcpRtoMin	INTEGER	no	Minimum timeout value permitted in a TCP implementation for the retransmission in milliseconds
3	tcpRtoMax	INTEGER	no	Maximum timeout value permitted in a TCP implementation for the retransmission in milliseconds
4	tcpMaxConn	INTEGER	no	Maximum number of TCP connection this entity supports
5	tcpActiveOpens	Counter	no	Total number of transitions to SYN_SENT state from CLOSED state
6	tcpPassiveOpens	Counter	no	Total number of transitions to SYN_RCVD state from LISTEN state
7	tcpAttemptFails	Counter	no	Total number of transitions to the CLOSED state from SYN_SENT or SYNRCVD states plus the transitions to LISTEN from SYN_RCVD
8	tcpEstabRestes	Counter	no	Total number of transitions to CLOSED state from ESTABLISHED or CLOSE-WAIT states
9	tcpCurrEstab	Gauge	no	Number of currently TCP connections in ESTABLISHED or CLOSE-WAIT states
10	tcpInSegs	Counter	no	Total number of segments received
11	tcpOutsegs	Counter	no	Total number of segments sent, excluding those containing only retranmitted octets
12	tcpRetransSegs	Counter	no	Number of segments transmitted with one or more previouly transmitted octets
14	tcpInErrs	Counter	no	Number of received segments with an error
15	tcpOutRsts	Counter	no	Number of transmitted segments with the RST flag set

The following table is tcpConnTable. It has the OID 13 and a row for each TCP connection:

OID	Name	Datatype	Writable	Description
1	tcpConnState	INTEGER	yes	Indicates the current state of the TCP connection. The user can only set the value 12, but can read: 1(closed), 2(listen), 3(synSent), 4(synReceived), 5(established), 6(finWait1), 7(finWait2), 8(closeWait), 9(lastAck), 10(closing), 11(timeWait), 12(deleteTCB)
2	tcpConn LocalAddress	IpAddress	no	Local IP address of the current connection. The value 0.0.0.0 indicates that the listener is willing to accept TCP connections on any interface
3	tcpConn LocalPort	Integer	no	Local port number of this TCP connection
4	tcpConnRem Address	IpAddress	no	Remote IP address of this TCP connection
5	tcpConn RemPort	Integer	no	Remote port number of the current TCP connection

06. UDP Monitoring

The udp group has the OID 1.3.6.1.2.1.7(mib.udp). It has only 4 variables and a table called udpTable. All these variables are ordered below by OID.

OID	Name	Datatype	Writable	Description
1	udpInDatagrams	Counter	no	Total number of UDP datagrams delivered to user processes
2	udpNoPorts	Counter	no	Number of UDP datagrams for which no application was in the destination port
3	udpInErrors	Counter	no	Total number of UDP datagrams that cannot be delivered for another reasons than no application at destination port
4	udpOut Datagrams	Counter	no	Total number of UDP datagrams sent

The table bellow lists the variables in the udpTable. This table has the OID 5.

OID	Name	Datatype	Writable	Description
1	udpLocal Address	IpAddress	no	Local IP address for the current listener. The value 0.0.0.0 indicates thath the listener is willing to receive datagrams on any interface
2	udpLocalPort	INTEGER	no	Local port number for the current listener

07. SNMP Monitoring

The snmp group is the object 1.3.6.1.2.1.11(mib.snmp). It has 28 variables with important information about the Simple Network Management Protocol.

OID	Name	Datatype	Writable	Description
1	snmpInPkts	Counter	no	Number of delivered messages to the SNMP entity from the transport service.
2	snmpOutPkts	Counter	no	Number of delivered messages from the SNMP entity to the transport service.
3	snmpInBad Versions	Counter	no	Total number of received messages from an unsupported SNMP version
4	snmpInBad Community Names	Counter	no	Total number of received messages with an unknowned community name
5	snmpInBad Community Uses	Counter	no	Total number of received messages with a not allowed operation
6	snmpInASN ParseErrs	Counter	no	Total number of received messages with errors in ASN.1 or BER
8	snmpIn TooBigs	Counter	no	Number of received PDU's with the error-status tooBig
9	snmpInNo SuchNames	Counter	no	Number of received PDU's with the error-status noSuchName
10	snmpInBad Values	Counter	no	Number of received PDU's with the error-status badValue
11	snmpIn ReadOnlys	Counter	no	Number of received SNMP PDU's with the error-status readOnly
12	snmpInGenErrs	Counter	no	Number of received SNMP PDU's with the error-status genErr
13	snmpInTotal ReqVars	Counter	no	Number of successfully retrieved MIB objects as result of received get-next and get-request messages
14	snmpInTotal SetVars	Counter	no	Number of successfully edited MIB objects as result of received set-request messages
15	snmpInGet Requests	Counter	no	Number of accepted and processed get-request messages
16	snmpInGetNexts	Counter	no	Number of accepted and processed get-next messages
17	snmpInSet Requests	Counter	no	Number of accepted and processed set-request messages
18	snmpInGet Responses	Counter	no	Number of accepted and processed get-response messages
19	snmpInTraps	Counter	no	Number of accepted and processed trap messages
20	snmpOut TooBigs	Counter	no	Number of sent PDU's with the error-status tooBig
21	snmpOutNo SuchNames	Counter	no	Number of sent PDU's with the error-status noSuchName
22	snmpOut BadValues	Counter	no	Number of sent PDU's with the error-status badValue
24	snmpOut GenErrs	Counter	no	Number of received SNMP PDU's with the error-status genErr
25	snmpOutGet Requests	Counter	no	Number of successfully generated get-request messages
26	snmpOut GetNexts	Counter	no	Number of successfully generated get-next messages
27	snmpOutSet Requests	Counter	no	Number of successfully generated set-request messages
28	snmpOutGet Responses	Counter	no	Number of successfully generated get-response messages
29	snmpOutTraps	Counter	no	Number of successfully generated trap messages
30	snmpEnable AuthenTraps	INTEGER	yes	Indicates if the SNMP agent is enabled to create authentication-failure traps. Two values are possible here: 1 for enable and 2 for disable