Patent ID: 6335933
Filing Date: 2002-01-01
Classification: H04L

Abstract:
In a frame-switched network apparatus, a method of sending frames from a sender to a receiver over a possibly unreliable channel, the method comprising the steps of:forming a frame at the sender, wherein the frame contains data to be transmitted to the receiver; including a frame identifier in the frame selected from a set of frame identifiers; retaining a copy of the frame at the sender; sending the frame from the sender to the receiver over the channel, independent of a presence of the receiver on the possibly unreliable channel; upon receipt of a frame at the receiver, identifying a frame identifier for the received frame; detecting, from the frame identifier, if a prior frame was missed; if a missed prior frame is detected in the step of detecting, sending a negative acknowledgment (nack) at least two times from the receiver to the sender, the nack including an indication of the missed prior frame; if a nack is received at the sender, determining the frame identifier of the missed prior frame and resending the missed prior frame if a copy of the missed prior frame is still retained at the sender; delaying a second nack from the receiver for a response period, wherein the response period is related to the time delay expected between sending the first nack and expected receipt of a retransmitted frame and is a dynamically determined time determined from measured frame travel times;. retransmitting the missed prior frame once for each nack received; and releasing, independent of an acknowledgment of a successful receipt of the transmitted frame by the receiver, the retained copy of the transmitted frame when a storage constraint is reached.