I recently upgraded Zabbix from version 6.0 to 7.0, and one of the major improvements is that you can use SNMP GETBULK when performing low-level discovery.

In this post, we will discover all the object identifiers (OIDs) representing the interface names (which start at OID 1.3.6.1.2.1.31.1.1.1.1) for a Cisco Nexus switch with IP 192.0.2.1.

The old discovery way – SNMP GET

To get the value of the (single) next OID you can use the snmpgetnext command:

$ snmpgetnext -On -v 2c -c example 192.0.2.1 1.3.6.1.2.1.31.1.1.1.1
.1.3.6.1.2.1.31.1.1.1.1.83886080 = STRING: mgmt0

The snmpgetnext command will in this example make Zabbix send a get-next-request packet to 192.0.2.1, and 192.0.2.1 will respond with a get-response packet:

Src        Dest       Info
Zabbix     192.0.2.1  get-next-request
                      1.3.6.1.2.1.31.1.1.1.1
192.0.2.1  Zabbix     get-response
                      1.3.6.1.2.1.31.1.1.1.1.83886080

To get the entire OID tree you can use the snmpwalk command:

$ snmpwalk -On -v 2c -c example 192.0.2.1 1.3.6.1.2.1.31.1.1.1.1
.1.3.6.1.2.1.31.1.1.1.1.83886080 = STRING: mgmt0
.1.3.6.1.2.1.31.1.1.1.1.151060481 = STRING: Vlan1
.1.3.6.1.2.1.31.1.1.1.1.335544320 = STRING: loopback0
.1.3.6.1.2.1.31.1.1.1.1.335544574 = STRING: loopback254
.1.3.6.1.2.1.31.1.1.1.1.436207616 = STRING: Ethernet1/1
.1.3.6.1.2.1.31.1.1.1.1.436208128 = STRING: Ethernet1/2
.1.3.6.1.2.1.31.1.1.1.1.436208640 = STRING: Ethernet1/3
.1.3.6.1.2.1.31.1.1.1.1.436209152 = STRING: Ethernet1/4
.1.3.6.1.2.1.31.1.1.1.1.436209664 = STRING: Ethernet1/5
.1.3.6.1.2.1.31.1.1.1.1.436210176 = STRING: Ethernet1/6
.1.3.6.1.2.1.31.1.1.1.1.436210688 = STRING: Ethernet1/7
.1.3.6.1.2.1.31.1.1.1.1.436211200 = STRING: Ethernet1/8
.1.3.6.1.2.1.31.1.1.1.1.436211712 = STRING: Ethernet1/9
.1.3.6.1.2.1.31.1.1.1.1.436212224 = STRING: Ethernet1/10
.1.3.6.1.2.1.31.1.1.1.1.436212736 = STRING: Ethernet1/11
.1.3.6.1.2.1.31.1.1.1.1.436213248 = STRING: Ethernet1/12
.1.3.6.1.2.1.31.1.1.1.1.436213760 = STRING: Ethernet1/13
.1.3.6.1.2.1.31.1.1.1.1.436214272 = STRING: Ethernet1/14
.1.3.6.1.2.1.31.1.1.1.1.436214784 = STRING: Ethernet1/15
.1.3.6.1.2.1.31.1.1.1.1.436215296 = STRING: Ethernet1/16

The snmpwalk command will repeatedly send SNMP get-next-request packets to 192.0.2.1 until the OID tree is built.

The new discovery way – SNMP GETBULK

SNMP supports the ability to retrieve multiple OIDs in a single request with the snmpbulkget command:

$ snmpbulkget -On -v 2c -c example 192.0.2.1 1.3.6.1.2.1.31.1.1.1.1
.1.3.6.1.2.1.31.1.1.1.1.83886080 = STRING: mgmt0
.1.3.6.1.2.1.31.1.1.1.1.151060481 = STRING: Vlan1
.1.3.6.1.2.1.31.1.1.1.1.335544320 = STRING: loopback0
.1.3.6.1.2.1.31.1.1.1.1.335544574 = STRING: loopback254
.1.3.6.1.2.1.31.1.1.1.1.436207616 = STRING: Ethernet1/1
.1.3.6.1.2.1.31.1.1.1.1.436208128 = STRING: Ethernet1/2
.1.3.6.1.2.1.31.1.1.1.1.436208640 = STRING: Ethernet1/3
.1.3.6.1.2.1.31.1.1.1.1.436209152 = STRING: Ethernet1/4
.1.3.6.1.2.1.31.1.1.1.1.436209664 = STRING: Ethernet1/5
.1.3.6.1.2.1.31.1.1.1.1.436210176 = STRING: Ethernet1/6

Similar to snmpwalk, the snmpbulkwalk command will repeatedly send SNMP getBulkRequest packets to the device until the OID tree is built:

Src        Dest       Info
Zabbix     192.0.2.1  getBulkRequest     
                      1.3.6.1.2.1.31.1.1.1.1
192.0.2.1  Zabbix     get-response
                      1.3.6.1.2.1.31.1.1.1.1.83886080
                      1.3.6.1.2.1.31.1.1.1.1.151060481       
                      1.3.6.1.2.1.31.1.1.1.1.335544320
                      1.3.6.1.2.1.31.1.1.1.1.335544574
                      1.3.6.1.2.1.31.1.1.1.1.436207616
                      1.3.6.1.2.1.31.1.1.1.1.436208128
                      1.3.6.1.2.1.31.1.1.1.1.436208640
                      1.3.6.1.2.1.31.1.1.1.1.436209152
                      1.3.6.1.2.1.31.1.1.1.1.436209664
                      1.3.6.1.2.1.31.1.1.1.1.436210176
Zabbix     192.0.2.1  getBulkRequest
                      1.3.6.1.2.1.31.1.1.1.1.436210176
192.0.2.1  Zabbix     get-response
                      1.3.6.1.2.1.31.1.1.1.1.436210688 
                      1.3.6.1.2.1.31.1.1.1.1.436211200
                      1.3.6.1.2.1.31.1.1.1.1.436211712
                      1.3.6.1.2.1.31.1.1.1.1.436212224
                      1.3.6.1.2.1.31.1.1.1.1.436212736
                      1.3.6.1.2.1.31.1.1.1.1.436213248
                      1.3.6.1.2.1.31.1.1.1.1.436213760
                      1.3.6.1.2.1.31.1.1.1.1.436214272
                      1.3.6.1.2.1.31.1.1.1.1.436214784
                      1.3.6.1.2.1.31.1.1.1.1.436215296

Upgrade your templates in Zabbix

In this post, we have seen that to retrieve the OID tree consisting of all the interface names from 192.0.2.1; snmpwalk required 10 times the amount of packets to achieve the same result as snmpbulkwalk:

Zabbix 6.0 – snmpwalk	Zabbix 7.0 – snmpbulkwalk
20 x get-next-request pakets	2 x getBulkRequest packets
20 x get-response packets	2 x get-response packets

I therefore highly recommend upgrading your existing SNMP templates in Zabbix, or doing a rewrite of your own templates, so that you can take advantage of SNMP GETBULK for low-level discovery.

Here is an example of a template utilizing snmpbulkwalk in Zabbix 7.0: OSPF by SNMP.