How fast should my DirectConnect ethernet connection be?

This is an important question, but one which is quite difficult to answer. Speeds will vary widely, whether you are connecting to another computer on DirectConnect, within the University network, or on different areas of the Internet. At any time, the speed of your connection to another site is only as fast as the slowest link between you and the other site (the bottleneck). This document is intended to provide an idea of what speed to expect under different circumstances, so you can determine whether your connection is working normally or if there is a problem that can be corrected.

The DirectConnect network operates at a theoretical maximum speed of 10 Mbps (Million bits per second). This is over a hundred times faster than the 56Kbps (Thousand bits per second) obtainable thorough a modem and is also faster than new high speed ADSL or cable modem connections which will soon be available commercially. The 10Mbps speed means you need an ethernet card which operates at least 10Mbps to use DirectConnect. If your ethernet card also operates at 100Mbps (Fast Ethernet) it will also work with DirectConnect but will only see speed improvements in the newly connected dorms.

Eight bits = one byte, so the theoretical speed of 10Mbps is equivalent to 1.25 Megabytes/sec. It is never possible to obtain the theoretical maximum speed due to the way in which ethernet works. In practice, 0.8 Megabytes/sec (800 Kbytes/sec) is the maximum speed you might obtain. The bandwidth (amount of data transferred per second) in different segments of DirectConnect is shared between all the users in that segment. This works well, as not everyone uses their connection simultaneously. Even when you do use your connection, typical usage is 'bursty' - you download a web page in a brief period, read it for a while, and then request the next page. As the usage isn't solid, many users can experience a high speed connection for the periods when they need it.

The University is charged, per megabyte, for data transferred over the Internet, and DirectConnect has to meet its share of these charges. To ensure the charges do not exceed the income from the DirectConnect subscription fees, limits are in place on data transferred directly from the Internet to DirectConnect. These limits don't apply to transfers from the rest of the University to DirectConnect.