In a network having one or more Audio Video Bridging (AVB) devices, non-AVB bridges are detected by transmitting a maintenance message, such as a unicast linktrace message, from one AVB device such as a residential gateway to another AVB device such as a set-top box or IPTV. AVB devices in the path provide replies indicating whether the port on which the linktrace message was received is connected to a non-AVB bridge. The disclosure has utility in diagnostics problems with IPTV in a network.