This post assumes a basic knowledge of SNMP and describes MIB-II OIDs that are handy for monitoring network devices – mainly switches and routers. These OIDs should be present on all SNMP capable devices.

These OIDs all sit under the MIB-II higherarchy

.iso.org.dod.internet.mgmt.mib-2.system.

sysName.0

String containing system name, if configured. Useful for working out which device you are querying.

.sysLocation.0

String containing system location, if configured. Again, useful for working out which device you are querying.

.sysUpTime.0

System uptime in 1/100 of a second. Useful for detecting recently restarted equipment. This counter is actually from the time SNMP was started but usually this is analogous to system uptime.

NOTE: For the following OIDs <int> is a integer corresponding to the interface number. So to find the description of interface three you need to query ifDescr.3

.ifDescr.<int>

String containing interface description, eg:

• FastEthernet0/1
• Serial0/2
• Loopback0

.ifType.<int>

Similar to ifDescr Gives more specific technical information on interface. Eg:

• ethernetCsmacd
• frameRelay
• softwareLoopback

A full list of interface types can be found here:
http://www.iana.org/assignments/ianaiftype-mib

.ifSpeed.<int>

Speed of interface in bits per second.

.ifOperStatus.<int>

Operational status of interface – up or down. Whether the interface is actually connected or not.

.ifAdminStatus.<int>

Administrative status of interface – whether the interface has been configured to be up or down. (For Cisco: shutdown / no shutdown)

.ifInUcastPkts.<int>

Number of inbound unicast packets received. An entry also exists for outbound packets: ifOutUcastPkts. For traffic statistics it is necessary to monitor the change in this value over time.

.ifInErrors.<int>

Total packet errors for this interface. Again, an equivalent entry also exists for outbound packets: ifOutErrors.

.ipInReceives.0

Total number of received IP packets

.ipInHdrErrors.0

Inbound IP packets discarded because of errors in header.

.ipInAddrErrors.0

Inbound Ip packets discarded because of addressing issues.

.ipInDiscards.0

Inbound IP packets discarded for other reasons (not header or address)

.ipOutNoRoutes.0

No route to host. High values indicate a routing issue.

And that is just about it…