FrontEnd Transport Connector Test

The Front End Transport Service service runs on all Client Access servers and acts as a stateless proxy for all inbound and outbound external SMTP traffic for the Exchange 2013/2016 organization. For outgoing messages, the Transport service on Mailbox servers uses Send connectors to communicate with the Receive connector of a Front End Transport service. The Receive connector then selects a Mailbox server based on the number and type of recipients and the proximity of the AD site and routes the message to that Mailbox server.

For incoming messages, the Receive connector on the Front End Transport service looks for a single healthy Transport service on a Mailbox server to receive the message. Then, via the Send connector on the Front End Transport service it routes the message to the Transport service on that Mailbox server.  

If an FET connector (Receive/Send) takes too long to select the Mailbox server or route messages to a Mailbox server, the delivery of incoming/outgoing emails is bound to be delayed. This is why, administrators need to keep track of how quickly each FET connector processes emails and identify that connector(s) that is highly latent. This is possible using the FrontEnd Transport Connector test. For every default and user-configured FET connector, this test reports the maximum time that connector took to proxy emails 90%, 95%, and 99% of the time. This will lead administrators to that connector which is most latent.

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

Agent deploying the test : An internal/remote agent

Outputs of the test : One set of results each for every Frontend Transport Connector on the CAS server

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 by this connector to proxy emails 90% of the time.

Secs

If the value of these measures is very high for a particular connector, then that connector is deemed to be highly latent. You may want to look into the configuration of that connector and figure out why it is so slow.

95th percentile message latency:

Indicates the maximum time taken by this connector to proxy emails 95% of the time.

Secs

99th percentile message latency:

Indicates the maximum time taken by this connector to proxy emails 99% of the time.

Secs