End to End Transport Latencies Test

Periodically, administrators need to monitor how long end-to-end message flow takes, so that probable slowdowns in mail delivery can be proactively detected and resolved, before users complain. To achieve this, administrators can use the End to End Transport Latencies test. This test monitors end-to-end mail flow, classifies latencies as high, medium, and low, and for each such classification, reports the maximum time  taken by the server for transporting mails from one end to another, 90%, 95%, and 99% of the time. This way, the test leads administrators to current/probable bottlenecks in mail flow.

Target of the test : A Microsoft Exchange 2013/2016 server

 Agent deploying the test : An internal agent

Outputs of the test : One set of results each for high, medium, and low latencies

Configurable parameters for the test
  1. Test period - How often should the test be executed
  2. Host - The host for which the test is to be configured.
  3. port – The port at which the host listens.
Measurements made by the test
Measurement Description Measurement Unit Interpretation

90th percentile message latency:

Indicates the maximum time taken for end-to-end email message flow 90% of the time.

Secs

If the value of these measures are consistently high, it could indicate bottlenecks in email flow. The reason for the same has to be ascertained and resolved, so that there is an uninterrupted flow of emails end-to-end. 

High latencies can be triggered by one or more of the following reasons:

  • A networking issue exists.
  • The Transport component of the Microsoft Exchange 2013/2016 is under a heavy load.
  • Some messages have been sent to large distribution groups.
  • A Transport Agent issue exists. For example, the antivirus agent or Rights Management Services agent may be experiencing an issue.

95th percentile message latency:

Indicates the maximum time taken for end-to-end email message flow 95% of the time.

Secs

99th percentile message latency:

Indicates the maximum time taken for end-to-end email message flow 99% of the time.

Secs