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Selecting the best method for your team requires understanding the options and selecting the solution that integrates well with your existing resources. In this article, we will:

• Define agent and agentless approaches
  
• Outline pros and cons for each approach
  
• Establish a strategy for cost-effective, scalable performance visibility

Defining Agent and Agentless

Agents are typically proprietary software loaded on to relevant application components, devices, and servers. The question to ask application performance management (APM) vendors is whether their platform requires software to be installed on your critical infrastructure.

If the answer is “yes,” the program you’re loading is most likely an agent, which gathers data and sends it to the console or platform for analysis. Agents can also perform tasks that impact or modify the operation of the device.

If the answer is “no,” the APM platform is likely relying upon polling technologies to acquire device performance and related application information. These solutions are typically referred to as agentless.

Agentless solutions often tap into pre-existing or native agents and reporting capabilities placed on the system or device by the infrastructure manufacturer. Utilizing intelligence from these native agents allows agentless solutions to track performance variables including power, CPU, and memory usage without affecting device performance. Additionally, using polling technologies like SNMP or querying Windows systems through WMI provides nearly limitless information about devices and hosted applications.

Assessing the Pros and Cons
The following chart outlines the benefits and costs of each option.

	Pros	Cons
Agent	Designed to provide critical management specific metrics Uses SSL or other encrypted methods to provide data Typically will auto-update to avoid maintenance overhead	Can impact critical infrastructure, consuming device’s CPU, memory, and storage Cannot monitor beyond system on which its installed Time-consuming deployment requires agents for every critical device monitored Every new server requires additional agents be purchased Only tracks conditions and metrics it has been designed to target Cloud vendor may prohibit agents; coverage of multiple VMs can be cost prohibitive
Agentless	Tracks performance without impacting devices Immediate device discovery and monitoring, once IP address and credentials provided Scales as fast as new devices can be added Any devices can be monitored with minimal deployment effort, not just critical devices Taps into cloud vendor APIs and mimics user experience via synthetic transactions	Data sources may not provide full or relevant data Typically requires pre-existing services and agents to be turned on; may also require changes to firewall On larger networks, polling needs to be spaced out enough to avoid overlapping executions

Establishing Effective Performance Visibility
Ultimately, each team must assess the merits of leveraging proprietary agents versus going agentless. As our discussion has shown, each has strengths and weaknesses. Many vendors now offer significant insight into the underlying health and status of the devices and network by exploiting the wealth of information infrastructure and application developers now incorporate directly into their solutions with native agents. Cloud providers as well are introducing APIs that can be readily supported by agentless solutions. This is an important point as cloud vendors generally forbid the placement of any agents within their environments.

Alternatively, if you have ready access to source code and/or require unique visibility into devices not available from agentless monitoring, then proprietary agents could be a consideration. For select applications, they can offer deep insight into application health at the expense of broad service support.

Finally, whether utilizing proprietary agents or an agentless approach, it is important to note that many solutions also provide packet-based analysis to monitor the flow of applications traversing the network. This integrated monitoring approach yields highly granular detail on the overall health of applications and infrastructure, enabling optimal operational efficiency and reduced MTTR when problems are detected.

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Expanding Visibility with NBAR and IP SLA

IP SLA and NBAR are important monitoring technologies that should be utilized for cost-effectively improving visibility and understanding of network and application performance.

What are NBAR and IP SLA Technologies?
Cisco offers enhanced monitoring functionality on select routers via NBAR and IP SLA technologies that examine, analyze and classify network traffic. Each operates independently and enables more effective management and improved performance, especially where the ability to install probes is restricted or network visibility is otherwise limited. Here is a summary of what each offers:

Network Based Application Recognition (NBAR) – a mechanism that classifies and regulates bandwidth for network applications to ensure that available resources are utilized as efficiently as possible. Read more.

Internet Protocol Service Level Agreement (IP SLA) – enables the creation of time-based network and services performance data which can be used to validate service level agreements. Read more.

Observer Infrastructure is designed to automatically request NBAR and IP SLA metrics when completing device discovery and polling. As a result, no setup is required and the resulting router parameters are comprehensively presented within a single interface.

Observer Infrastructure can monitor the current status in real-time while also capturing data for long-term retrieval. It also allows event monitoring and alarming capabilities of any IP SLA or NBAR metric that exceeds critical user-defined thresholds. Use these technologies as a cost-effective way to expand visibility and eliminate questions about the root cause of poor application performance, the allocation of IT resources, or violations in agreed service levels.

 

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Cisco Live! in London

Attending Cisco Live in London? Join us on Tuesday, Jan 31, and Thursday, Feb 2, to learn how two enterprise customers, Capita and Kingspan, have optimized their networks and applications with the Observer platform. Also, stop by our Stand E37/E40 to view the latest in performance management and analysis, and try your luck at winning a Canon® DSLR Camera. Read more.

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