Abstract: System and methods for an interface alteration device placed between a first segment and a second segment of a communication line of a vehicle. The interface alteration device identifies portions of an incoming data stream that are to be transmitted to a second interface alteration device and causes the identified portions to be transmitted to the second interface alteration device; identifies portions of the incoming data stream that are to be replaced by data received over a data link from the second interface alteration device; and generates an outgoing data stream that is a replicate of the incoming data stream except that the portions of the incoming data stream identified to be replaced are replaced with the corresponding data received from the second interface alteration device.

Abstract: System and methods for an interface alteration device that recognizes in incoming data whether certain predefined conditions exist based on condition evaluation rules, and, as appropriate, alters certain portions of the incoming data based on alteration rules. Transmission tolerance levels also define how transmission of data is to be performed so that the destination node to which the altered and/or unaltered data is transmitted will be unaware that alteration has occurred to the data stream.