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How to find out what's slowing you down

You've increased your TCP Receive Window, but what if you're still not getting the speed you expect? (1500 Kbits/sec ADSL service is capable of downloading at a bit more than 150 KBytes/sec.) It could just be a matter of a remote server with limited capacity. But it could also be a network under-capacity problem at your ISP (the result of overselling the available capacity to too many subscribers, an all too common problem). No matter what you may have heard or read, "the Internet" is not overloaded.

The usual symptoms of network under-capacity are high latency (the time it takes a packet to cross the network path from one end to the other) and packet loss (where transmitted data is literally lost because of insufficient network capacity). High latency has an adverse effect on interactive use; e.g., real-time gaming over the Internet. Packet loss has an adverse effect on just about everything.

The best way to pinpoint the source of a network problem is to use a standard TCP/IP network tool called 'traceroute', which measures both latency and packet loss at every network "hop" between you and your destination (remote server). Windows 95/98/Me/NT/2000/XP comes with a free version of traceroute called "tracert". It does a pretty good job, but the output can be hard to understand if you're not into networking. (See Microsoft's Q162326 "Using TRACERT to Troubleshoot TCP/IP Problems in Windows NT" [which also applies to Windows 95/98/Me])