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IT technical memo of networking

Monitoring the Usage of DHCP scope with ZABBIX (SNMP MIB)

f:id:daichi703n:20160908013830j:plain

To monitor the DHCP scope usage of Windows Server by the MIB in ZABBIX.
DHCP is used in many enterprise LAN, therefore, if there are no remaining of IP address, PC cannot be set address and it is a fatal service impact.
A problem does not occur if strictly manage the connection terminal, but there is also such as the use of wireless LAN, there is a limit to the management.
Therefore, by monitoring the usage of the DHCP scope, we plan to look forward to the subnet extension. And, the recovery of excess it becomes possible to reverse.

DHCP MIB

MIB OID of DHCP are defined as follows. Here describes the DHCP MIB of Windows Server, which has been widely used.

Type MIB OID
dhcpScope 1.3.6.1.4.1.311.1.3.2
scopeTable 1.3.6.1.4.1.311.1.3.2.1
scopeTableEntry 1.3.6.1.4.1.311.1.3.2.1.1
subnetAdd 1.3.6.1.4.1.311.1.3.2.1.1.1
noAddInUse (Used IPs) 1.3.6.1.4.1.311.1.3.2.1.1.2
noAddFree (Available IPs) 1.3.6.1.4.1.311.1.3.2.1.1.3
noPendingOffers 1.3.6.1.4.1.311.1.3.2.1.1.4

The combination of these, can be visualized the usage of DHCP scope.

(reference) Free DHCP-MIB SNMP MIB Download - Free MIB Download - Search MIBs - OiDViEW

ZABBIX Discovery settings

Important function of the use of ZABBIX, Discovery. It is possible to create an item and graph automatically in DHCP scope.

At the time of item set, the key and the item name without forgetting the #SNMPVALUE (or #SNMPINDEX). "SNMPVALUE of subnetAdd" = "SNMPINDX of other items", the possible either. If you forget this item can not be obtained in duplicate.

Discovery
subnetAdd
1.3.6.1.4.1.311.1.3.2.1.1.1

ZABBIX 3.x The discovery of how to set to specify the changes OID as follows. discovery[{#SNMPVALUE},1.3.6.1.4.1.311.1.3.2.1.1.1]

Items Recommend to the graph stacked three or less.
noAddInUse (Used IPs)
1.3.6.1.4.1.311.1.3.2.1.1.2.{#SNMPVALUE}

noAddFree (Available IPs)
1.3.6.1.4.1.311.1.3.2.1.1.3.{#SNMPVALUE}

noPendingOffers
1.3.6.1.4.1.311.1.3.2.1.1.4.{#SNMPVALUE}

Charting image

Graph I think is easy to see to create stacked.

Green the noAddInUse, the noAddFree blue, the noPendingOffers in red. In such a graph.

f:id:daichi703n:20160908013021p:plain

noPendingOffers might be unnecessary.

Defect information

In WindowsServer2008, with a look at the DHCP payout situation and the Server Manager that can be acquired in the MIB, there is that there is a difference. Basically, but I practical usage in the latest numeric of the Server Manager, or less than the actual or often paid out when viewed in the SNMP MIB, it seems to take a few hours to reflect. MIB of information would not be updated successfully.

Conclusion

The SNMP MIB, in ZABBIX, it is possible to monitor and visualize the usage of the DHCP scope. This allows the scope extended planned.


This Blog is English Version of my JP's.

Sorry if my English sentences are incorrect.

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