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Cisco ThousandEyes Technical Part 2 : Tests

November 26, 2021 ,

ThousandEyes: Technical Part 2



Today we are going where we left last time. Yes, todays topic is Tests. Agents are doer and what they do are called the tests. If you have not gone through other articles on ThousandEyes series, please go through them to stay updated.

Tests are scheduled and there are 5 broad categories (Layers). These layers are –

  • Routing Layer
  • Network
  • DNS
  • Web
  • Voice

Each layer has multiple tests that can be selected for different insights and visibility that you want to accomplish. 

Routing Layer – collects the routing information available in public Internet domain. Public routing domain information is shared by cloud agent using the BGP test. ISPs and large organizations share the routing information over internet using BGP – and this information enables reachability over internet. 

  • BGP Test – using BGP test network admin gets insight into routes that gets advertised in public domain in real time. Also helps to detects BGP route leaks, route hijacking, unexpected path changes, and route flapping. BGP Route visualization page in ThousandEyes dashboard provide you the collected information by BGP test. This information can be used proactively to troubleshoot the routing issues in public domain and escalate the matter to ISPs for their attention and remediation.
Network Layer – consists of two tests and the purpose of these tests to measure the performance of a network between two endpoints. SLAs Packet Loss, Latency, and Jitter is measured as a result of the test. This can also perform the traceroute – displayed in path visualization view of dashboard. 

  • Agent to Server Test – for measuring the performance of a remote target server from a vantage point. This server an enterprise or public server that is reachable over Internet.
  • Agent to Agent Test – same metrics that agent to server test performs but can also perform the bidirectional network throughput.

Figure 1: Path Visualization View

DNS Layer – helps network administrator to troubleshoot the issues when a particular web server/service is not available due to problem in DNS lookup mechanism. DNS Layer tests are to verify the DNS Server are resolving applications’ domain and working as expected.

  • DNS Server Test – allows to lookup a specific DNS domain record by selecting different domain servers that you want to test and compare their performance – provide you availability and the resolution time.
  • DNS Trace Test – helps to ensure that all authoritative servers work as expected. This test uses the recursive lookup for a domain – starting with root till authoritative server. This allows to examine the complete hierarchy of a domain to find out the potential issues much faster.
  • DNSSEC Test – used to verify the Digital signature of the DNS record.

Web Layer – used as handy tool for network administrator to test the SaaS Applications or Web applications. This layer has multiple tests as below -

  • HTTP Server Test – sends the HTTP request to the server and check the HTTP response code if the response is received. This test uses the metrics – availability, response time and throughput. 
  • Page Load Test – helps to understand the time a page takes to load. This time load metric consists of all DOM components that needs to be downloaded and rendered. Those objects download times are used to understand by a web page is loading slowly and how it can be optimized.
  • Transaction Test – emulates the user transaction with a website. Actions on the website are explained using the scripts that are executed by the agents – actions can include “Button Click”, “File Download”, “Form Submission” and so on. The test scrips are written in JavaScript, and there is another way of using the ThousandEyes Recorder program where you can record your interaction with website and convert the same to script – and use the same with test.
  • FTP Server Test – used to test a server running TFP, Secure FTO. As a part of the test network administrator can perform the authentication; download, upload and listing directory tests. It provides the availability, response time and throughput.

Voice Layer – being a sensitive nature of the voice traffic, voice layer provides the set of tests that allows you to troubleshoot the voice related issues due to latency and jitter on the network.

  • SIP Server Test – checks the availability of a SIP on the server that provides the signaling the registration. Using metrics such as availability, response time and total time to troubleshoot the SIP Server performance issues.
  • RTP Stream Test – measures the quality of the call stream. This covers the network performance characteristics of between the endpoints. As a part of metrics covers MOS, corruptions, latency and packet delay variation.

Agent to Test Compatibility Matrix

Yes, it is the fact that not all tests are supported by each agent type. To help you below compatibility matrix can be used for reference -

Figure 2: Agent to Test Compatibility

What is Test Nesting?

Cisco ThousandEyes tests are nested to save cost and provide the comprehensive visibility. As an example, if you configure a HTTP Server – that automatically utilizes the network and routing layer tests to provide you more comprehensive insight. It’s always a good practice to avoid redundant tests to avoid duplication of data. All the nested tests can be viewed at the time of defining the test using “Views Enabled for This Test” option –

Figure 3:Web Page Load Teat with Nested Tests

Hope you find this informative and next we’ll be next talking more deeply about most widely deployed use cases.