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How to Use SNMP for Network Management & Configure SNMP Trap Receivers

SNMP trap receivers are systems or software components designed to receive and process SNMP traps — which are asynchronous notifications sent from network devices like switches, routers, or servers.

Purpose of SNMP Trap Receivers:

  1. Alert Monitoring
    They receive traps (alerts) when something important happens on a network device — such as link down, CPU overload, temperature warnings, or failed logins.
  2. Real-Time Fault Detection
    Since traps are sent immediately when an event occurs, trap receivers help admins respond quickly to network issues.
  3. Logging Events
    Trap receivers often log received traps into databases or monitoring systems for analysis, audits, or reporting.
  4. Triggering Automated Actions
    Some systems can act on specific traps — for example, sending an email, creating a ticket, or rebooting a service.

Example:

  • A router detects that one of its interfaces has gone down.
  • It sends an SNMP trap to the trap receiver.
  • The trap receiver logs the event and alerts the network admin or monitoring dashboard

Software Required

MapleLink Lite User Interface (Enter the network switch’s IP address into a web browser to access its web interface.


Hardware Required


What is SNMP

Simple Network Management Protocol (SNMP) is a standard protocol used in network management systems to monitor and manage devices connected to a network. It helps detect conditions that may require administrative attention, such as faults or performance issues. Developed by the Internet Engineering Task Force (IETF), SNMP is part of the Internet Protocol Suite and includes an application-layer protocol, a standardized data model (schema), and a collection of data objects.

SNMP makes management data available through variables on the devices it monitors. These variables represent aspects of the device’s configuration and status. Network management applications can query these variables to gather information and, in some cases, modify them to update device settings.


SNMP Configuration

Allows the user to enable or disable the SNMP protocol globally. By default, SNMP is disabled. The user can also customize the system name, as well as specify the system location and contact information as needed.

NodeCommandDescription
enableshow snmpThis command displays the SNMP configurations
configuresnmp (disable/enable)This command diables/enables the SNMP on the switch.
configuresnmp system-name
STRING
This command configures a name for the system. (The System Name is same as the host name).
configuresnmp system-location
STRING
This command configures the location information for the system.
configuresnmp system-contact
STRING
This command configures contact information for the system

Example:
– L2SWITCH#configure terminal
– L2SWITCH(config)#snmp enable
– L2SWITCH(config)#snmp system-contact IT engineer
– L2SWITCH(config)#snmp system-location Branch-Office

ParameterDescription
SNMP StateSelect option to enable / disable the SNMP on the switch
System NameUser can configure system name
System LocationUser can configure the switch deployed location for reference
System ContactUser can configure System Contact person information like name or number

SNMP Community Name

An SNMP Community Name is basically like a password or key that allows access to a network device’s management information using SNMP (Simple Network Management Protocol). It’s used mainly in SNMP v1 and v2c, which don’t have strong authentication.

Here’s the breakdown:

  • Purpose: It controls who can read or modify information on a device like a router, switch, or server.
  • Types:
    • Read-only community (commonly public) – allows viewing device information but not changing it.
    • Read-write community (commonly private) – allows viewing and modifying settings.
  • Usage: When an SNMP manager queries a device, it includes the community name. If the device recognizes it, it responds; if not, access is denied.

Think of it like a door key: the right key lets you in (read or write), the wrong key leaves you outside.

SNMP Community Strings:

In SNMP v1 and SNMP v2c environments, community strings function like passwords and are used to define the security parameters for SNMP clients. By default, the SNMP community string is set to “public” for both versions.

Network ID of Trusted Host:

The IP address consists of two parts: the Network ID and the Host ID, where:

  • Network ID = (Host IP & Subnet Mask)

When configuring a trusted host, users should enter only the Network ID, leaving the Host ID as 0.
– For example, if a user enters the full IP address 192.168.1.102, the system will automatically reset the Host ID, resulting in 192.168.1.0.

Configuration

NodeCommandDescription
configuresnmp community STRING (ro/rw) trusted-host IPADDR/Subnet MaskThis command configures the SNMP community name, Permissions (ro/rw), Trusted host IP/Subnet mask.

Example:
– L2SWITCH#configure terminal
– L2SWITCH(config)#snmp community public rw trusted-host 192.168.200.106/24

ParameterDescription
Community StringEnter a Community string; this will act as a password for requests
from the management station.
An SNMP community string is a text string that acts as a
password. It is used to authenticate messages that are sent between
the management station (the SNMP manager) and the device (the
SNMP agent). The community string is included in every packet
that is transmitted between the SNMP manager and the SNMP
agent.
RightsSelect Read-Only to allow the SNMP manager to use this string
to collect information from the Switch.
Select Read-Write to allow the SNMP manager to use this string
to create or edit MIBs (configure settings on the Switch).
Network ID of Trusted HostType the IP address of the remote SNMP management station in
dotted decimal notation, for example 192.168.1.0.
Number of Mask BitType the length of the subnet mask bits.
ApplyClick Apply to for settings to take effect.
RefreshClick Refresh to begin configuring this screen afresh.
No.This field displays the index number of an entry.
Community StringThis field displays the community string of an entry.
RightsThis field displays the right of an entry.
Network ID of
Trusted Host
This field displays the network ID of trusted host of an entry.
Number of Mask
Bit
This field displays the length of the subnet mask bits of an entry.
ActionClick the Delete button to remove the entry.

SNMP Trap Event Settings

The features allow users to enable/disables individual trap notifications.

NodeCommandDescription
enableshow snmp trap-eventThis command displays the SNMP
configurations.
configuresnmp trap-event alarmover-
heat
(disable/enable)
This command enables/disables the alarmover-
heat trap.
configuresnmp trap-event alarmover-
load
(disable/enable)
This command enables/disables the alarmover-
load trap.
configuresnmp trap-event alarmpower-
fail
(enable/enable)
This command enables/disables the alarmpower-
fail trap.
configuresnmp trap-event bpdu
(disable/enable)
This command enables/disables the BPDU
port state change/BPDU Root Guard/BPDU
Guard trap
configuresnmp trap-event loop-detection
(disable/enable)
This command enables/disables the loopdetection
trap.
configuresnmp trap-event portadmin-
state-change
(disable/enable)
This command enables/disables the portadmin-
state-change trap.
configuresnmp trap-event portlink-
change
(disable/enable)
This command enables/disables the port-linkchange
trap.
configuresnmp trap-event powersource-
change
(disable/enable)
This command enables/disables the powersource-
change trap.
configuresnmp trap-event stptopology-
change
(disable/enable)
This command enables/disables the stptopology-
change trap.
configuresnmp trap-event trafficmonitor
(disable/enable)
This command enables/disables the trafficmonitor
trap.

Configuration

The features allow users to enable/disables individual trap notification.

Alarm-Over-Heat
Alarm-Over-Load
Alarm-Power-Fail
– Trap when the system’s temperature is too high.
– Trap when system is overloaded.
– Trap when system power is over voltage/under
– voltage/RPS over voltage/RPS under voltage.
BPDU-Guard
Loop-Detection
– Trap when port is blocked by BPDU Guard/BDPU
Root Guard/BPDU port state changed.
– Trap when port is blocked by Loop Detection
Port-Admin-State-Change
Port-Link-Change
STP-Topology-Change
Traffic-Monitor
– Trap when port is enabled/disable by administrator.
– Trap when port linking up/down is changed.
– Trap when the STP topology changes.
– Trap when port is blocked by Traffic Monitor.
ParameterDescription
Select allEnables all trap events.
Deselect AllDisables all trap events.
ApplyClick Apply to configure the settings.
RefreshClick Refresh to begin configuring this screen afresh.

SNMP Port Link-Change Trap Settings

The features allow users to enable/disables port-link-change trap notification by individual port.

Configuration:

NodeCommandDescription
enableshow snmp port-link-change-trapThis command displays the SNMP
port link-change trap configurations.
interfacesnmp port-link-change-trapThis command enables the link
change trap on the specific port.
interfaceno snmp port-link-change-trapThis command disables the link
change trap on the specific port.
configinterface range (fastethernet1/0/ |
gigabitethernet1/0/) PORTLISTS
This command enters the interface configure node.
if-rangesnmp port-link-change-trapThis command enables the link
change trap on the specific ports.
if-rangeno snmp port-link-change-trapThis command disables the link
change trap on the specific ports.
ParameterDescription
PortSelects the range of ports.
StateUser can enable /disable trap events when port link change.
ApplyClick Apply to configure the settings.
RefreshClick Refresh to begin configuring this screen afresh.

SNMP Trap Receiver Settings

SNMP Trap Receiver Configuration

NodeCommandDescription
configuresnmp trap-receiver IPADDR VERSION COMMUNITY StringThis command configures the trap receiver’s configurations, including the IP address, version (v1 or v2c) and community String.
ParameterDescription
IP AddressEnter the IP address of the remote trap station in dotted decimal notation.
VersionSelect the version of the Simple Network Management Protocol to use. v1or v2c.
Community StringSpecify the community string used with this remote trap station.
ApplyClick Apply to configure the settings.
RefreshClick Refresh to begin configuring this screen afresh.
Trap Receiver List
No.This field displays the index number of the trap receiver entry. Click the number to modify the entry.
IP AddressThis field displays the IP address of the remote trap station.
VersionThis field displays the version of Simple Network Management Protocol in use. v1or v2c.
Community StringThis field displays the community string used with this remote trap station.
ActionClick Delete to remove a configured trap receiver station.

Real-Life Scenario

Scenario: Automated Manufacturing Plant — CNC Machine Network Monitoring

Setting:

An automated manufacturing facility uses a fleet of CNC (Computer Numerical Control) machines controlled and monitored through a centralized network. Each CNC machine, along with supporting devices like industrial switches, PLCs (Programmable Logic Controllers), temperature controllers, and power supply units, is SNMP-enabled.

The Problem:

One day, a network switch connecting several CNC machines begins to overheat due to a failing internal fan. If it fails completely, it will halt production in that section of the plant.

The Role of SNMP Trap Receivers:

  • The network switch detects the high internal temperature and sends an SNMP trap to the plant’s SNMP trap receiver system.
  • The SNMP trap receiver logs the event and recognizes it as a critical temperature threshold breach.
  • Within milliseconds, it:
    • Alerts the plant’s IT team via SMS and email.
    • Creates a ticket in the facility’s maintenance ticketing system.
    • Automatically activates backup routing, rerouting network traffic to maintain uptime while technicians investigate.
    • Logs the event in the central monitoring dashboard for auditing.

Outcome:

Thanks to the SNMP trap receiver:

  • A costly shutdown is avoided.
  • The maintenance crew is dispatched in time to replace the failing fan before complete hardware failure.
  • The incident is logged for regulatory and insurance compliance.

Resources & Documentation

Lite-Managed Network Switches Resources:

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