Emulating links with WANem
If you're planning to publish applications on geographic links, it's very important to test how those applications perform and you'll learn later in this chapter, how the optimizations work for improving the user experience.
Plan a complete UAT (User Acceptance Test) phase before going to production, if possible with real users. In this paragraph you'll learn how to use an opensource tool, WANem, to emulate a WAN link.
I usually prepare some test scenarios, and ask users to give a score from 1 (bad) to 5 (good) for the user experience. Here's an example of the feedbacks I got from a test session, varying bandwidth (columns) and latency (rows) and without any optimizations:
|
Time |
100 Kb/s |
200 Kb/s |
300 Kb/s |
500 Kb/s |
|---|---|---|---|---|
|
10 ms |
2 |
3 |
4 |
5 |
|
50 ms |
2 |
2 |
3 |
4 |
|
150 ms |
1 |
1 |
1 |
2 |
Installing
WANem is distributed as a bootable CD, based on Linux Knoppix. The operating system runs live from the CD, that is, you don't need to install it on the machine's hard disk.
WANem does...
