The Simple Network Management Protocol (SNMP) sure does pack a punch for something with “simple” in its name, as it literally provides the lifeblood of network monitoring and device communications. Network admins rely heavily on SNMP because nearly every technology manufacturer supports the protocol. And, in turn, it enables them to collect information, configure devices and receive alerts about network performance and issues.
What is SNMP?
To break it down, SNMP consists of numerous standards for network management, including an application layer protocol and a database schema architecture.
The protocol leverages the client-server model. Servers, called managers, collect and process information about devices on the network. Clients, called agents, are any type of device on the network that sends data to the managers. The managers and agents communicate by leveraging several protocol data units:
- GetRequest – Retrieve the value of a variable from a manager to an agent.
- SetRequest – Change the value of a variable from a manager to an agent.
- GetNextRequest – Find variables from a manager to an agent; can also be executed as a bulk request to many agents.
- Response – Receive replies from agents to a manager through the return of variables.
- Trap – Receive simultaneous messages from agents to a manager.
- InformRequest – Generate simultaneous messages between managers.
- Report – Review messages and determine problem types detected by agents.
The protocol exposes management data in the form of variables on managed systems that describe the system status and configuration. The variables can be remotely queried and manipulated.
Why is SNMP Important?
SNMP provides greater visibility and understanding of servers to workstations, printers, hubs, switches, routers and more across your IP networks. Without SNMP, it becomes more difficult to monitor and manage network devices efficiently, especially at scale. You also can’t collect information on network throughput, usage, performance issues and security breaches.
SNMP monitoring plays a critical role in this visibility, providing near real-time data and alerts that help administrators proactively manage and troubleshoot their networks. Another cool feature of SNMP is that it has a negligible impact on the performance of your devices and minimal transport requirements not to impact network traffic.
How Does SNMP Work?
To keep it simple, SNMP provides a seamless way to monitor network devices, automate routine checks and facilitate quicker issue responses without manually accessing each device.
SNMP operates through a straightforward communication model between two main components: the manager and the agent.
The manager is typically a centralized system or application responsible for monitoring the network.
The agent is a small piece of software embedded in network devices such as routers, switches or servers. It collects data about the device’s performance and status.
The interaction between the two is based on a series of commands. The manager can request specific information, such as memory usage or network traffic, using a GET request. If it needs to change a configuration, it sends a SET command. Devices can also send alerts, known as TRAPs, to notify the manager of critical events like hardware failures or unexpected reboots.
MIB and SNMP
Another vital component of SNMP is the Managed Information Base (MIB). This text file contains hierarchically organized information about the data collected from a particular device. MIB is included in all SNMP-enabled devices and is converted by the protocol into a format usable by monitoring software.
The hierarchy feature is crucial. All the manageable features from different vendor devices can be properly organized with a name and a number that consists of an Object Identifier (OID), an internal component of the MIB. An OID’s job is to analyze each piece of data and provides a unique address pointing to a specific metric or setting.
In addition to polling and information exchange, SNMP sends data packages without explicit requests. You can preconfigure these SNMP “traps” to let clients know about specific changes in the device. The setting up of control commands is yet another SNMP capability that lets the client (monitoring software) make configuration changes within the device.
SNMP typically uses the lightweight User Datagram Protocol (UDP) for communication, which, while efficient, is less reliable than Transmission Control Protocol (TCP). To address this, SNMPv3 introduced encryption and authentication to maintain data integrity and confidentiality.
Should I Use the Newest Version of SNMP?
The first version of SNMP launched in the 1980s and is still used on the public Internet. For your internal networks, it’s important to use the most current version (SNMPv3), which is also an Internet standard. It features improved security and device access by authenticating and encrypting data packets to block external intruders from accessing.
SNMPv3 gives administrators the flexibility to apply four different security levels—depending on what types of users and data each device handles, and whether a network is closed or open:
- Authentication Only
- Privacy Only
- Authentication and Privacy
- No Privacy and No Authentication
New system admin capabilities are another SNMPv3 feature. These include notification originators and proxy forwarders, which assist in remote configuration and device support. They also streamline large-scale device deployments, device accounting and fault management.
Other key features of SNMPv3 include message integrity checking and assurance that messages come from reliable sources. The protocol also provides read-only messages to designated recipients and ones intercepted by unauthorized users are automatically garbled.
While it’s a good practice to use SNMPv3 to improve your security posture, it shouldn’t be your only option. For example, you should also separate user roles and assign proper credentials for each device. And be sure to apply access control lists to block unauthorized device access.
Keep It Simple, Simon
A network administrator’s job is challenging. But SNMP makes it, like its namesake, more “simple.” As one of the most vital tools any IT professional can use, SMMP provides teams with the ability to proactively monitor devices and centralize management across numerous locations to swiftly detect and resolve issues. For organizations that have highly complex networks, SNMP helps cut through the noise and helps them support their employees, whether they are in the office or working at home.