---
title: TCP layer fields
description: None TCP network layer related fields. TCP layer round trip times. Duration required to establish a TCP connection based on already available IP address...
url: https://www.elastic.co/elastic/docs-builder/docs/3028/reference/beats/heartbeat/exported-fields-tcp
products:
  - Beats
  - Heartbeat
applies_to:
  - Elastic Cloud Serverless: Generally available
  - Elastic Stack: Generally available
---

# TCP layer fields
None

## tcp

TCP network layer related fields.
<definitions>
  <definition term="tcp.port">
    Service port number.
    type: alias
    alias to: url.port
  </definition>
</definitions>


## rtt

TCP layer round trip times.

## connect

Duration required to establish a TCP connection based on already available IP address.
<definitions>
  <definition term="tcp.rtt.connect.us">
    Duration in microseconds
    type: long
  </definition>
</definitions>


## validate

Duration of validation step based on existing TCP connection.
<definitions>
  <definition term="tcp.rtt.validate.us">
    Duration in microseconds
    type: long
  </definition>
</definitions>