Delay and Loss in Packet Switching Network

Delay and Loss in Packet Switching Network

• Cause of Delay?
• because of sharing
• Buffering --> Delay --> Loss
• Delay Types
• Transmission Delay
• Transmission Delay = Data sizes / Transmission speed(bandwidth=BW)
• Propagation Delay
• It causes between node and node
• Propagation Delay = Link length / Propagation speed 
• Processing Delay
• It depends on varity things, so typically ignored
• Sometimes, that is allowed(ex. equals to Transmission Delay)
• Queuing Delay
• It depends on state of buffer(or queue)
• typically ignored
• Packet Loss
• queue(=buffer) preceding link in buffer has finite capacity
• packet(arriving to full queue) dropped(=lost)
• lost packet may be retransmitted by previous node, by source end system, or not at all
• Total Delay = all of them
• Efficiency of transmission = Transmission Delay / Total Delay

참고 : 컴퓨터 네트워크  by 김성철교수