Agentless Monitoring Definition

Agentless monitoring is a less intrusive method of network observation using application-specific APIs and various network protocols, such as SNMP and WMI, to observe the overall performance of your network assets, such as servers and applications.

Agentless vs. agent-based monitoring

Network monitoring tools help track your overall network health by offering real-time information about your network components. These tools utilize two methods to capture performance metrics from your network devices. In the agent-based monitoring method, they install lightweight software, also known as the monitoring agent, on your network devices to track their uptime and performance. The monitoring agent is primarily responsible for capturing performance data from your infrastructure components (servers, applications, etc.) and sending it back to the monitoring tool for further analysis.

In the agentless monitoring approach, these tools utilize specific networking protocols (SNMP, WMI, etc.), application-specific APIs, or built-in monitoring agents to track the health of your network devices. This monitoring method doesn't require the installation of a dedicated or third-party monitoring agent on every network component, making it easier than the agent-based approach. There is no clear choice between monitoring methods, as each has certain advantages and disadvantages. You should consider your organization's requirements before choosing a particular monitoring approach.

For instance, if all the devices in your network are of the same type and use similar network protocols, then agentless monitoring can be a viable option. However, if you require granular visibility into your IT infrastructure, then agentless monitoring will be more useful. Ideally, opt for a monitoring tool providing both agent-based and agentless monitoring capabilities to observe your IT environment effectively.

Outlined below are some of the other key differences between agentless and agent-based monitoring:

• Deployment timeframe: Setting up agent-based monitoring takes a significant amount of time since it requires the installation of a dedicated monitoring agent on every network component. In contrast, you can start with agentless monitoring instantaneously since it doesn't need a dedicated monitoring agent for every network device. The ease of deployment and lower upfront costs makes agentless monitoring highly useful for smaller organizations with limited IT budget and resources.
• Security: In the agentless approach, the monitoring tools utilize the interfaces for remote access to devices. Any small vulnerability in the device interface can result in a security failure. Similarly, the primary monitoring tool also acts as a single point of failure in agentless monitoring since it has administrator-level access to network resources. Agent-based monitoring, on the other hand, is much safer comparatively. It creates an encrypted communication link between the monitoring agent and the primary monitoring tool, ensuring both parties can securely exchange network performance data.
• Cost of ownership: Agentless monitoring solutions save you valuable time as you can deploy and use them instantaneously. These solutions also help curtail maintenance costs since you don’t need to worry about upgrading the monitoring agents installed on your network devices. With less overhead and maintenance hassle, the cost of ownership of agentless monitoring tools is minimal. In contrast, agent-based monitoring is a resource-intensive process requiring upgrades to the agent software with every network refresh. With more tools to maintain and configure, the total cost of ownership is comparatively higher in agent-based monitoring.
• Depth of metrics: While agentless monitoring is a less complex process, it doesn't provide in-depth data regarding your network performance. The standard performance metrics offered by agentless monitoring tools might be good enough for monitoring the performance of a small network; however, these metrics aren't good enough for analyzing the health of a large network. In contrast, agent-based monitoring helps you obtain granular data about your network performance, regardless of the size and complexity. The software agents installed on the network devices collect a broader set of metrics to help you track your network health effectively and troubleshoot issues quickly.
• Agent overhead: Most network devices you monitor using the agentless method have a built-in monitoring agent. Calculating the overhead of this native monitoring agent is challenging since there is no single OS-level process under which it runs. In contrast, agent-based monitoring makes agent overhead calculating pretty straightforward. It allows you to calculate the overhead by checking the resource usage of the process under which the agent software runs.

When to use agentless monitoring?

Agentless monitoring allows you to seamlessly observe your infrastructure components' overall health and performance without installing the agent software. It helps you retrieve the performance metrics from various network components quickly. The agentless approach also helps reduce the cost and complexity of infrastructure operations and maintenance (O&M). Given these benefits, most monitoring solutions in the market are transitioning to agentless or providing support for both agent and agentless monitoring.

Outlined below are some of the scenarios when agentless monitoring can be helpful for your business:

• Homogenous network environment: If most of the devices connected to your network are of the same type or support similar network protocols, then you can easily consider agentless monitoring for your IT infrastructure. For instance, you can easily enable agentless monitoring when all the devices in your network have a pre-installed SNMP agent. Enabling agentless monitoring becomes easier when your network devices are managed from a centralized location.
• High-level monitoring: Agentless monitoring can be helpful in scenarios where you want to track the high-level performance metrics of your infrastructure components, such as device uptime and CPU utilization. High-level performance metrics obtained through agentless monitoring are more useful when you run a small, localized network with homogenous devices.
• Non-standard technology: With the increasing security threats in this digital age, monitoring every component of your infrastructure, including non-standard network devices such as HVAC systems, is essential. The agentless monitoring approach can be handy for observing such non-standard IP-enabled devices. It can help you quickly locate and manage these devices from a centralized facility.
• Fast implementation: Most small organizations with limited IT resources want to perform infrastructure monitoring quickly. They prefer a shorter deployment timeframe with minimal overhead expenses. The agentless monitoring approach can be most effective for such organizations since it allows them to track IT assets immediately without installing third-party agent software.

Outlined below are some popular infrastructure assets that you can monitor in an agentless manner:

• Network devices: Since most network devices support SNMP polling, you can easily observe their health and performance in an agentless manner.
• Storage devices: You can track the performance status of SAN and NAS storage arrays in an agentless fashion using the SMI-S protocol.
• Hypervisors: Popular hypervisors, such as VMware vSphere and Oracle VM server, provide web service APIs for agentless monitoring. Polling these APIs enables you to track the performance of the hypervisors and the virtual machines hosted on them.
• Virtual desktops: You can retrieve data regarding resource usage inside VM, top resource consuming process, and user experience information such as screen refresh latency from a virtual desktop in an agentless way.
• Virtual servers: Cloud servers, such as Amazon EC2, provide cloud APIs for agentless server monitoring.
• Hyperconverged infrastructure (HCI): HCI solutions such VxRail and VMware vSAN help you gather their performance metrics through RESTful APIs in an agentless manner.
• User experience monitoring: The user experience of both web and non-web applications can be monitored in an agentless manner. Synthetic and real-user monitoring are the two methods through which you track the end-user experience of the web apps.

Agentless monitoring tools

Modern network monitoring tools come with both agent-based and agentless monitoring capabilities to help you seamlessly observe your entire IT infrastructure, including on-premise, cloud, and hybrid applications. As an agentless monitoring tool, they utilize various protocols (SNMP, WMI, etc.) and rest APIs to quickly locate and observe the servers, applications, and other devices connected to your network. An agentless network monitoring tool can help you build an up-to-date network map to understand the complex relationship between your network components, including application dependencies. It also allows you to monitor your overall network health and identify key trends by analyzing key performance metrics on a unified dashboard, such as CPU utilization and network bandwidth.

Network management software with agentless monitoring capabilities can also provide timely alerts whenever a particular device or application surpasses a critical threshold. This helps you quickly identify and fix critical issues and avoid unexpected network outages. You can set up these alerts based on various metrics such as CPU utilization, packet loss rate, and response time. An agentless monitoring tool can also offer customized, data-rich reports to help you closely track and compare your network performance over specific time intervals. It also allows you to effectively monitor your virtualized resources, such as virtual servers and SaaS applications, by gathering their performance metrics through cloud APIs.

Advanced agentless monitoring tools enable you to utilize predefined templates and create custom workflows to streamline the network performance management tasks. These tools can also help you maintain an up-to-date IT asset inventory by offering real-time information about all the devices connected to your network. The inventory lists created by these tools update automatically whenever a device joins or leaves your network. Additionally, you can use these tools to view critical details about your network hardware and software for improved inventory lifecycle management, such as purchase date and warranty expiration date.