If the bandwidth of your server is insufficient to handle its workload, it is likely that clients will be aware of it before the server is. Client requests to the server will be rejected or will time out, or response will be delayed. On the server side, the indicators are less clear. The server will continue to establish connections, receive requests, and transmit data.
Bandwidth shortages are not uncommon. They have even been observed on dedicated Internet Information Servers with dedicated T1 lines. Traffic generated by an Internet Information Server alone can easily saturate a 1.5 – megabytes per second T1 line.
You can detect a bandwidth shortage on your server (perhaps even before clients do) by monitoring the success and failure of connections established and rejected by TCP. When the bandwidth is ample, the server can establish and serve connections before they time out. If bandwidth is not sufficient, the connections fail.
The following section describes the Performance Monitor counters recommended for monitoring the success and failure of connections on your server.