What is Network Management System?
- A Network Management System (NMS) is a software system used by network administrators to monitor, manage, configure, and troubleshoot network devices such as routers, switches, servers, access points, and firewalls.
An NMS helps the administrator know:
- Whether a network device is working or not
- How much bandwidth is being used
- Whether there are errors or failures
- CPU and memory utilization of devices
- Network traffic and performance
- When a device goes down or comes back up
Basic NMS Diagram
NETWORK MANAGEMENT SYSTEM
(NMS Server)
│
┌─────────┴─────────┐
│ │
SNMP SNMP
│ │
┌──────▼──────┐ ┌──────▼──────┐
│ Router │ │ Switch │
│ SNMP Agent │ │ SNMP Agent │
└─────────────┘ └─────────────┘
│ │
│ │
┌─────▼─────┐ ┌─────▼─────┐
│ Server │ │ Access │
│SNMP Agent │ │ Point │
└───────────┘ │SNMP Agent │
└───────────┘- The NMS Server communicates with network devices and collects information about their status and performance.
2. What is SNMP?
SNMP stands for Simple Network Management Protocol.
- It is an application-layer protocol used to monitor and manage network devices over an IP network.
SNMP is commonly used with:
- Routers
- Switches
- Servers
- Printers
- Firewalls
- Wireless Access Points
- UPS systems
SNMP generally uses UDP for communication.
- UDP Port 161 → Used for SNMP queries/responses
- UDP Port 162 → Used for SNMP Trap messages
3. SNMP Architecture
SNMP mainly consists of three important components:
1. SNMP Manager
The SNMP Manager is usually part of the NMS.
It requests and receives information from network devices.
2. SNMP Agent
An SNMP Agent is software running on a managed network device.
It collects information about the device and provides that information to the SNMP Manager.
3. MIB
MIB stands for Management Information Base.
It is a structured collection of information/objects that can be monitored or managed through SNMP.
Examples:
- Device uptime
- Interface status
- Number of received packets
- Number of transmitted packets
- Error counts
- CPU-related information, when exposed by the device
4. SNMP Architecture Diagram
┌─────────────────────────┐
│ Network Manager │
│ / NMS │
│ (SNMP Manager) │
└────────────┬────────────┘
│
SNMP Messages
│
─────────────┼─────────────
│
┌──────────────────┼──────────────────┐
│ │ │
┌─────▼─────┐ ┌─────▼─────┐ ┌─────▼─────┐
│ Router │ │ Switch │ │ Server │
│SNMP Agent │ │SNMP Agent │ │SNMP Agent │
└─────┬─────┘ └─────┬─────┘ └─────┬─────┘
│ │ │
┌──▼──┐ ┌──▼──┐ ┌──▼──┐
│ MIB │ │ MIB │ │ MIB │
└─────┘ └─────┘ └─────┘5. How SNMP Works
Suppose a network administrator wants to know whether a router's interface is working.
Step 1: NMS sends a request
The SNMP Manager sends a GET request to the router's SNMP Agent.
NMS / Manager
│
│ SNMP GET
▼
┌───────────┐
│ Router │
│SNMP Agent │
└───────────┘Step 2: Agent checks the information
The SNMP Agent looks at the required object in its MIB.
Step 3: Agent sends response
The agent sends the requested information back to the NMS.
NMS / Manager
▲
│ SNMP RESPONSE
│
┌───────────┐
│ Router │
│SNMP Agent │
└───────────┘The NMS can then display the information to the administrator.
6. Important SNMP Operations
1. GET
Used by the manager to request information from an SNMP agent.
Manager ───── GET ─────► Agent
Manager ◄── RESPONSE ── AgentExample:
"Tell me the status of interface 1."
2. GETNEXT
Used to retrieve the next object in the MIB hierarchy.
It is useful when walking through a group of MIB objects.
3. GETBULK
Used to retrieve large amounts of management information efficiently.
It is mainly associated with SNMPv2c and SNMPv3.
4. SET
Used by the manager to change a configurable value on a device.
Manager ───── SET ─────► Agent
Manager ◄── RESPONSE ── AgentExample:
Changing a configurable network parameter, if the device permits it.
5. TRAP
A Trap is an unsolicited message sent by the SNMP Agent to the Manager when an important event occurs.
For example:
Router
│
│ Interface Down
▼
SNMP Agent
│
│ SNMP TRAP
▼
NMS
│
▼
Administrator Alert6. INFORM
Inform is similar to a Trap, but it requires an acknowledgment from the receiver.
7. SNMP Message Flow
┌──────────────────┐
│ NMS │
│ SNMP Manager │
└────────┬─────────┘
│
┌───────────┼───────────┐
│ │ │
GET SET GETBULK
│ │ │
▼ ▼ ▼
┌────────────────────────────┐
│ Network Device │
│ SNMP Agent │
│ │
│ MIB │
└─────────────┬──────────────┘
│
TRAP / INFORM
│
▼
NMS8. Example of SNMP in a College Network
Suppose a college has:
- 2 Routers
- 10 Switches
- 3 Servers
- 20 Access Points
The administrator can install an NMS and enable SNMP agents on the devices.
NMS SERVER
┌────────────┐
│ SNMP │
│ Manager │
└─────┬──────┘
│
College Network
│
┌─────────────┬──────┼──────┬─────────────┐
│ │ │ │ │
Router Switch Server AP Firewall
SNMP Agent SNMP Agent Agent Agent AgentThe administrator can monitor:
- Device availability
- Interface status
- Network traffic
- Packet errors
- Bandwidth utilization
- Device uptime
- Other supported device statistics
If a switch goes down, the NMS can receive an alert and notify the administrator.
9. SNMP Versions
| Version | Important Feature |
|---|---|
| SNMPv1 | Original/basic version |
| SNMPv2c | Improved operations and performance; community-based security |
| SNMPv3 | Adds stronger security features such as authentication and encryption |
For modern deployments, SNMPv3 is generally preferred when supported because it provides security features that older community-string-based versions do not.
10. Advantages of NMS and SNMP
Advantages of NMS
- Centralized network monitoring.
- Helps detect network failures quickly.
- Makes troubleshooting easier.
- Provides performance information.
- Can generate alerts and reports.
- Helps administrators monitor large networks.
Advantages of SNMP
- Simple and widely supported.
- Works with many types of network devices.
- Provides centralized monitoring.
- Supports automatic alerts through Trap/Inform.
- Helps collect network performance information.
Short Exam Definition
Network Management System (NMS) is a software system used to monitor, manage, configure, and troubleshoot network devices from a centralized location.
SNMP (Simple Network Management Protocol) is an application-layer protocol used to monitor and manage network devices. It uses an SNMP Manager, SNMP Agent, and MIB for network management.
Remember this diagram for exam
┌─────────────────┐
│ NMS / SNMP │
│ Manager │
└────────┬────────┘
│
SNMP Messages
│
┌──────────────┼──────────────┐
▼ ▼ ▼
┌────────┐ ┌────────┐ ┌────────┐
│ Router │ │ Switch │ │ Server │
│ Agent │ │ Agent │ │ Agent │
└───┬────┘ └───┬────┘ └───┬────┘
▼ ▼ ▼
MIB MIB MIB