The solution of the present invention provides systems and methods for encoding information into an Internet Protocol identification field (IPID) of an IP layer header of a network packet in a manner acceptable to many or all of the network devices that encounter the encoded packet. In one embodiment, the solution described herein encodes the IP identification field of the IPID header with information to be communicated between devices. Appliances may use the encoded IP field as a signal or a means for a low-bandwidth subcarrier of data between the appliances that is transparent to any intervening network equipment. For example, the encoded field may be used to announce or probe the presence of a device, a functionality or capability of device or to indicate a type or speed of a network connection of a port on a device.