VCT Configuration Notes

The Virtual Cable Test (VCT) is not an IEEE standard. VCT uses Time Domain Reflectometry (TDR) to send a signal to a remote partner that loops back to the same port. Different vendors and remote partners may have different techniques, terms, and implementations.

VCT can be performed when the link partner is auto-negotiating. It must be run in auto-negotiation and full-duplex mode. Auto-negotiation is a process where devices share their capabilities regarding transmission parameters such as speed, duplex mode, and flow control, then choose the highest performance mode supported by both devices.

VCT supports:

  • Copper ports with 2.5G/10G or 1G, depending on chip type.
  • Ports that are actively connected and operational; disconnected or inactive ports cannot be tested.
  • Four pairs per interface, per cable.
  • Most types of RJ-45 cables, including Cat 3, 4, 5, 6, and 7.
  • Only on-demand Command Line Interface (CLI) requests for diagnostics, requiring you to trigger the test for a port connected with the cable.
Parent topic: Virtual Cable Testing