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2.2 | |
Bandwidth | |
| 2.2.6 | |
Data transfer calculation |
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Network designers and administrators are
often called upon to make decisions regarding bandwidth. One decision
might be whether to increase the size of the WAN connection to
accommodate a new database. Another decision might be whether the
current LAN backbone is of sufficient bandwidth for a streaming-video
training program. The answers to problems like these are not always
easy to find, but one place to start is with a simple data transfer
calculation.
Using the formula transfer time = size
of file / bandwidth (T=S/BW) allows a network administrator to
estimate several of the important components of network performance.
If the typical file size for a given application is known, dividing
the file size by the network bandwidth yields an estimate of the
fastest time that the file can be transferred.
Two important points should be considered when doing this calculation.
Although the data transfer calculation is quite simple, one must be careful to use the same units throughout the equation. In other words, if the bandwidth is measured in megabits per second (Mbps), the file size must be in megabits (Mb), not megabytes (MB). Since file sizes are typically given in megabytes, it may be necessary to multiply the number of megabytes by eight to convert to megabits. Try to answer the following question, using the formula T=S/BW. Be sure to convert units of measurement as necessary.
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