3.2.5.5 Other Message Received

If any message other than a correctly formatted INITIAL_OFFER_MESSAGE (section 2.2.1.3) request, SEGMENT_INFO_MESSAGE (section 2.2.1.4) request, or BATCHED_OFFER_MESSAGE (section 2.2.1.5) request response is received on the port which the client is currently using for this protocol, the message MUST be dropped and the protocol sequence aborted.