Network(5) -- Delay, Loss, and Throughput in Packet-Switched Networks

Delay, Loss, and Throughput in Packet-Switched Networks

Overview of Delays

The most important of these delays are the nodal processing delay, queuing delay, transmission delay, and propagation delay. Together, these delays give a total nodal delay.

Processing Delay

The time required to examine the packet’s header and determine where to direct the packet is part of the processing delay. It also include the time needed to check for bit-level errors in the packet. In microseconds.

Queuing Delay

It waits to be transmitted onto the link.

The number of packets that an arriving packet might expect to find is a function of the intensity and nature of the traffic arriving at the queue. In microseconds to milliseconds.

Transmission Delay

Our packet can be transmitted only after all the packets that have arrived before it have been transmitted.

• The length of the packet: L bits.
• Transmission rate: R bits/sec.

Then, the transmission delay is L/R. In microseconds to milliseconds.

Propagation Delay

The time required to propagate from the beginning of the link to router B is the propagation delay.

The propagation delay is the distance between two router A and router B and s is the propagation speed of the link.

The difference between transmission delay and propagation delay

• The transmission delay is the amount of time required for the router to push out the packet; it is a function of the packet’s length and the transmission rate of the link, but has nothing to do with the distance between the two routers.
• The propagation delay is the time it takes a bit to propagate from one router to the next; it is a function of the distance between the two routers, but has nothing to do with the packet’s length or the transmission rate of the link.