Line loopback enables frames received on a network port to be retransmitted to the same network port without involving the host CPU.
Frames are looped back to the same port without being modified. This includes the FCS which is not recalculated.
The line-loopback functionality and the filtering/capturing functionality can be used independently of each other. A port with line loopback enabled can at the same time be used to capture, for instance, all received IP frames.
The line-loopback functionality can be enabled using the config tool or using NTAPI.
# Enable line loopback on port 0. /opt/napatech3/bin/config --cmd set --port 0 --line_loopback onIt can also be configured using the NT_ConfigWrite function with the NT_CONFIG_PARM_PORT_SETTINGS_V2 parameter and the NtPortSettings_v2_s structure. Set NtPortSettings_v2_s.lineLoopback to 0 or 1 (see DN-0449).