Internet Help

What is bandwidth?

Bandwidth is a time measurement, so 1 Megabit (Mb) really means 1 Megabit per second (Mbps). Bandwidth refers to the maximum flow of data possible on a given connection or link, but bandwidth is rarely used at 100-percent capacity. There are numerous reasons for this, including:

• The TCP communication protocol typically doesn’t use all of the available bandwidth
• Throughput, or the usage of bandwidth
• Internet traffic and congestion
• The server speed of the Web sites you visit
• Traffic and congestion on private or corporate networks

What is throughput?

Throughput is the usage of bandwidth, typically measured in percentage. When dealing with Internet traffic speed, throughput is typically a more important measurement of actual data transfer, compared to bandwidth.

• Bandwidth is a time measurement. 1 megabit (Mb) really means 1 Megabit per second (Mbps).
  • If a 1 Mb network connection sends 1 Mb of data per second, throughput is 100 percent.
  • If a 1 Mb network connection only sends 700 Kilobytes (Kb) of data per second, throughput is 70 percent.

Throughput can be affected by several factors.

• TCP and the receive window
• Internet traffic and congestion
• The server speed of the Web sites you visit
• Traffic and congestion on private or corporate networks

You can usually modify the TCP receive window to enhance throughput.

What is TCP?

TCP is the main communication protocol used for transferring data on the Internet; it’s how machines pass data back and forth.

There are many aspects to how TCP works. One of the most important aspects is called the receive window. Simply put, when TCP is used to receive data, the recipient machine will advertise the maximum number of bytes it can receive before an acknowledgement must be sent to the sending machine, telling it the data arrived intact.

In most cases, increasing the default TCP receive window size will increase throughput. The receive window size for most applications is typically no larger than 64 KB.