1. Optimizing Bandwidth Utilization Defiana Arnaldy, M.Si 0818 0296 4763 deff_arnaldy@yahoo.com

2. Overview Introduction Tricks and tips to increase performance Multicast UDP Data compression Conclusion

3. Introduction You can’t always expect your customer to have the same bandwidth as your office LAN. Huge numbers of people still use modem connections, and some use mobile GPRS devices with even lower connection speeds. These customers will only buy your software if it works at a speed that is at least usable and does not frustrate them

4. Example – Microsoft Terminal Services (MTS)  not free – VNC (www.realvnc.com)  freewww.realvnc.com Both pieces of software allow you to control another computer remotely

5. Tricks and tips to increase performance Performance increases can often be made by simple changes to how data is moved between client and server In some cases, these techniques may not be applicable; however when used correctly, each of the following methods will help keep your data moving quickly.

6. Caching Keep-alive connections Progressive downloads Tweaking settings

7. Caching Caching can increase network performance by storing frequently accessed static data in a location that provides faster data return than the normal access time for the static data It is important that all three of the following criteria are met: – The data must be frequently accessed – The data must not change as often as it is requested – The access time for cached data must be substantially faster than the access time to receive the data directly

8. Keep-alive connections Even though most Web pages contain many different images that all come from the same server, some older (HTTP 1.0) clients create new HTTP connections for each of the images This is wasteful because the first HTTP connection is sufficient to send all of the images. Luckily, most browsers and servers are capable of handling HTTP 1.1 persistent connections

9. Progressive downloads When most of a file is downloaded, the client should be able to begin to use the data The obvious applications are audio and video, where users can begin to see and hear the video clip before it is fully downloaded.

10. Tweaking settings Windows is optimized by default for use on Ethernets, so where a production application is being rolled out to a client base using modems, ISDN, or DSL, some system tweaking can be done to help Windows manage the connection more efficiently and, ultimately, to increase overall network performance

11. Multicast UDP Multicasting is where a message can travel to more than one destination at the same time This can provide significant increases in efficiency where there is more than one recipient of the data being sent

12. The first audio multicast took place in 1992, followed one year later by the first video multicast. Nowadays, multicast UDP is used in products such as Symantec Ghost to provide remote software installations on multiple hosts simultaneously. It is also used to broadcast video footage of popular events over the Internet.

13. Multicast basics Multicast routing Implementing multicast

14. Data compression The most effective way to send data between computers faster is to send less data lossless compression  The process of compressing data so that the decompressed data is identical to the original – used in ZIP compression lossy compression  The process of compressing data in a way that is not identical, but is not perceived as different from the original, – used in JPEG and Mp3 compression.

15. Lossless compression Lossy compression – Audio compression – Image compression – Video compression

16. Conclusion Lossless data compression guarantees the integrity of data, As long as the server and client have the processing power to compress and decompress the data at a rate faster than the amount of time it would take to send the data over the wire, then compression is an excellent means of accelerating your applications’ communications.