Original:
http://wzw19191.blog.sohu.com/135110823.html
The concept of propagation delay refers to the time delay of electromagnetic signals or optical signals in the transmission medium. In optical fibers or copper wires, the propagation speed of optical signals and electromagnetic signals is above 200,000 km/s. In the transmission is electromagnetic signals or optical signals, not data!
Transmission delay refers to the time required for the node to enter the data block from the node to the transmission medium when sending data, that is, from the first bit of the data block to the end of the last bit. time. Transmission delay is also called transmission delay
The bandwidth, also known as the media access rate, is the rate at which data enters the media from the node.
The propagation delay has nothing to do with the size of the data to be sent. The size of the sent data is only related to the sending delay, because sending delay = data/bandwidth, and propagation delay = sending distance/propagation rate, in optical fiber, twisted pair, In transmission media such as cables, the propagation rate is fixed. Therefore, the propagation delay is mainly related to the transmission distance! It has nothing to do with the size of the data sent!
http://answers.yahoo.com/question/index?qid=20090218195707AA8qyoK
transmission delay
In a network based on packet switching, transmission delay (or store-and-forward delay) is the amount of time required to push all of the packet’s bits into the wire. In other words, this is the delay caused by the data-rate of the link.
Transmission delay is a function of the packet’s length and has nothing to do with the distance between the two nodes. This delay is proportional to the packet’s length in bits,
It is given by the following formula:
DT = N / R
where
DT is the transmission delay
N is the number of bits, and
R is the rate of transmission (say in bits per second)
Most packet switched networks use store-and-forward transmission at the input of the link. A switch using store-and-forward transmission will receive (save) the entire packet to the buffer and check it for CRC errors or other problems before sending the first bit of the packet into the outbound link. Thus store-and-forward packet switches introduce a store-and-forward delay at the input to each link along the packet’s route.
http://www.answers.com/transmission%20de…
propagation delay
The time required for a signal to pass through a given complete operating circuit; it is generally of the order of nanoseconds, and is of extreme importance in computer circuits.
The time it takes to transmit a signal from one place to another. Propagation delay is dependent solely on distance and two thirds the speed of light. Signals going through a wire or fiber generally travel at two thirds the speed of light.
Networking
Propagation delay is defined as the amount of time it takes for a certain number of bytes to be transferred over a medium. Propagation delay is the distance between the two routers divided by the propagation speed.
Propagation delay = d/s where d is the distance and s is the speed.
In electronics, digital circuits and digital electronics, the propagation delay, or gate delay, is the length of time starting from when the input to a logic gate becomes stable and valid, to the time that the output of that logic gate is stable and valid. Often this refers to the time required for the output to reach 50% of its final output level when the input changes. Reducing gate delays in digital circuits allows them to process data at a faster rate and improve overall performance.
The difference in propagation delays of logic elements is the major contributor to glitches in asynchronous circuits as a result of race conditions.
The principle of logical effort utilizes propagation delays to compare designs implementing the same logical statement.
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