Endpoint Agent TCP Support

ThousandEyes supports using TCP as the communication protocol for Endpoint Agent scheduled tests. Two modes of operation are supported:

  • SACK-based measurements

  • SYN-based measurements

SACK-based network measurements require a single TCP connection to perform the measurement, whereas SYN-based measurements use a stream of up to 50 SYN packets, each being sent from a unique source TCP port. For this reason, SACK-based measurements are preferred. However, some networks do not support SACK, and so SYN is necessary.

For more information on the difference between SACK- and SYN-based measurements, see Network Tests Explained.


There are a number of reasons to use TCP-based tests over ICMP-based tests. Some of those reasons include:

  • Large enterprise networks often block ICMP packets entirely to protect against device discovery.

  • For networks running QoS or similar configurations, ICMP packets are often assigned a low priority, and packet loss/latency can occur.

  • ICMP packets take different routes to TCP packets, and are often slower.

For more information on the difference between TCP and ICMP, see Network Tests Explained.


TCP support is available for Endpoint Agent version 1.75.0 and above.

TCP Setup

Create TCP Scheduled Tests

See Configure Scheduled Tests for instructions on creating tests, and Endpoint Agent Test Settings Reference for specific configuration options.

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