SNMP OID: Full Insight

 SNMP uses OIDs to uniquely identify pieces of data (like CPU usage, interface status, etc.).

• Standard OIDs (defined by IETF) are common across all devices, e.g.:

• 1.3.6.1.2.1.1.1.0 → sysDescr (system description)

• 1.3.6.1.2.1.2.2.1.10 → ifInOctets (interface input bytes)

• Vendor-specific OIDs:

For example:

Vendor	Enterprise OID Base	Example
Cisco	1.3.6.1.4.1.9	1.3.6.1.4.1.9.1.516 (Cisco 2960 model)
Juniper	1.3.6.1.4.1.2636	Juniper-specific OIDs
HP	1.3.6.1.4.1.11	HP printer/router OIDs
Fortinet	1.3.6.1.4.1.12356	FortiGate device OIDs

Part 1: Standard SNMP OID – .1.3.6.1.2.1.1.1.0

This is used for system description, and it works on all SNMP-supported devices (routers, switches, servers, etc.).

Let’s break this path:

🔹 .1 → iso

International Organization for Standardization
This is the root of the SNMP OID tree. Every OID begins from here.

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🔹 .3 → org

Organization
This level is used for organizations that are registered under ISO.

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🔹 .6 → dod

Department of Defense (USA)
Historically, internet protocols like SNMP, TCP/IP were developed under DoD — that’s why this is here.

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🔹 .1 → internet

This node refers to Internet protocols like SNMP, TCP/IP, etc.

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🔹 .2 → mgmt

Management
This branch contains standard SNMP management objects.

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🔹 .1 → mib-2

Management Information Base version 2
This is a standard set of objects used across all SNMP devices. It includes system info, interfaces, network protocols, etc.

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🔹 .1 → system

This group contains general system-level information.

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🔹 .1 → sysDescr

System Description
This OID returns info like OS name, version, hardware model, firmware, etc.

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🔹 .0 → Instance

This indicates a scalar value (single result) — not a table.

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🔸 Visual Breakdown:

markdown
.1.3.6.1.2.1.1.1.0
| | | | | | | | |____ Instance (0)
| | | | | | | |______ sysDescr
| | | | | | |________ system
| | | | | |__________ mib-2
| | | | |____________ mgmt
| | | |______________ internet
| | |________________ dod
| |__________________ org
|____________________ iso

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✅ Part 2: Vendor-Specific SNMP OID – .1.3.6.1.4.1.9

This is used by vendors (Cisco, HP, Juniper, Fortinet, etc.) to define their custom/private OIDs.

Let’s explain each part:

🔹 .1 → iso

(Same as above)

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🔹 .3 → org

(Same as above)

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🔹 .6 → dod

(Same as above)

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🔹 .1 → internet

(Same as above)

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🔹 .4 → private

This branch is used for non-standard, vendor-specific objects. Not globally standardized.

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🔹 .1 → enterprises

This subtree contains registered vendors — each one has a unique number.

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🔹 .9 → Cisco

Cisco’s enterprise number is 9. So .1.3.6.1.4.1.9 points to Cisco's private SNMP space.

Cisco will have further sub-paths here, like:

• .1.3.6.1.4.1.9.9.43.1.1.1.0 → config last changed

• .1.3.6.1.4.1.9.2.1.56.0 → CPU load

• etc.

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🔸 Visual Breakdown:

markdown
.1.3.6.1.4.1.9
| | | | | | |____ Cisco's Enterprise ID (9)
| | | | | |______ enterprises
| | | | |________ private
| | | |__________ internet
| | |____________ dod
| |______________ org
|________________ iso

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💡 Summary:

Node	Meaning	Used For
.1	iso	Root of the SNMP tree
.3	org	Registered organizations
.6	dod	Origin of Internet protocol
.1	internet	Internet-related protocols
.2	mgmt	Standard management data
.1	mib-2	Common SNMP groups
.1	system	General system info
.1	sysDescr	System description text
.4	private	Vendor-defined MIBs
.1	enterprises	Vendors list
.9	Cisco	Cisco's private SNMP objects

Core MIB‑II System Objects (.1.3.6.1.2.1.1)

These objects provide basic device/system information:

OID	Name	Description
.1.3.6.1.2.1.1.1.0	sysDescr	System description (OS, firmware, etc.)
.1.3.6.1.2.1.1.2.0	sysObjectID	Device’s vendor-specific OID
.1.3.6.1.2.1.1.3.0	sysUpTime	Time since last reboot (TimeTicks)
.1.3.6.1.2.1.1.4.0	sysContact	Administrator contact info reference
.1.3.6.1.2.1.1.5.0	sysName	Hostname or device name
.1.3.6.1.2.1.1.6.0	sysLocation	Device’s physical location
.1.3.6.1.2.1.1.7.0	sysServices	Services supported by the device
Cisco Community+12Dell+12Sysadmin MD+12Fortinet Community+5Observium+5Alvestrand+5

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🌐 Interfaces Group (.1.3.6.1.2.1.2)

Standard interface statistics and status:

OID	Name	Description
.1.3.6.1.2.1.2.1.0	ifNumber	Number of network interfaces
.1.3.6.1.2.1.2.2.1.ifIndex	ifIndex	Interface index (row identifier)
.1.3.6.1.2.1.2.2.1.2.ifIndex	ifDescr	Interface description (e.g. GigabitEthernet1/0/1)
.1.3.6.1.2.1.2.2.1.10.ifIndex	ifInOctets	Bytes received
.1.3.6.1.2.1.2.2.1.16.ifIndex	ifOutOctets	Bytes transmitted
.1.3.6.1.2.1.2.2.1.14.ifIndex	ifInErrors	Input packet errors
.1.3.6.1.2.1.2.2.1.20.ifIndex	ifOutErrors	Output packet errors
Wikipedia+3Observium+3Sysadmin MD+3

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📊 Protocol and Management Groups

Additional useful standard MIB‑II subtrees:

• SNMP group (.1.3.6.1.2.1.11) — handles SNMP-specific stats, such as number of get/set requests, errors, traps generated/received Sysadmin MD+1Alvestrand+1

• IP group (.1.3.6.1.2.1.4) — IP statistics, routing table entries Server Fault+11Observium+11Alvestrand+11

• TCP/UDP groups (.1.3.6.1.2.1.6, .1.3.6.1.2.1.7) — connection state, retransmissions, datagram counts Observium

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✅ Summary: Most Useful SNMP Standard OIDs

• System info: sysDescr, sysName, sysUpTime, sysContact, sysLocation, sysServices

• Interface metrics: ifDescr, ifInOctets, ifOutOctets, ifInErrors, ifOutErrors

• Protocol-level statistics: SNMP counters, IP, TCP, UDP stats