Extension devices such as upstream facing port devices (UFP devices) and downstream facing port devices (DFP devices) connect via an extension medium. When a UFP device and a DFP device pair with each other, DisplayPort video and/or audio information from a DisplayPort source device can be presented by a DisplayPort sink device, which are coupled to the UFP device and DFP device, respectively. In some embodiments, the DFP device may train a DisplayPort link to the DisplayPort sink device regardless of whether it is receiving actual data from a UFP device, and may provide placeholder data to the DisplayPort sink device in order to keep the link active. The DFP device may then replace the placeholder data with the actual data from the UFP device, once received, and may thereby seamlessly switch the DisplayPort sink device from presenting placeholder data to presenting data from the DisplayPort source device.