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Figure 4 - Frame structure for various Ethernet frame lengths |
Delay
Delay is the data packet transmission time from a source to a receiverdefined as the time it takes for a packet to travel from the source to the destination. The delay's value consists of depends on the following partsaspects:
- Signal propagation time The signal's propagation duration in the medium: depends on the medium physical characteristics , of the medium and it is nonzero in any case.
- Serialization time: the conversion of a bitstream to a signal and backward by the incoming/outgoing interfaces is not instantaneous and requires makes use of the hardware resources of a the network device.
- Processing time: the time spent by the data packet spends is in inside the network device. This time depends on the status of the packet queues statusqueue, as a data packet will be processed only after processing the packets placed in this queue earlier.
The delay is often measured, as a round-trip time (RTT), i.e. the time it takes for the data packet to be transmitted from a source to a destination and backward. For example, this value is used can be seem in the ping command's results. The state of time it takes for the intermediate network devices during processing to process the data packets forward and backward may differ, therefore, usually the round-trip time is not equal to two the double of the one-way delaysdelay.
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Figure 5 - Example of data transfer delay |
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