Eicon Networks DIVA LAN ISDN manual Data compression

Chapter Five: Minimizing ISDN Charges Data compression 69

Data compression

Data compression increases the effective throughput of a B-channel by encoding data so that fewer bits are required to represent it. Popular compression algorithms typically reduce the size of the data by 50 percent, effectively doubling the rate at which it is transmitted.

However, not all types of data lend themselves to such high compression ratios. If you are transmitting ZIP files, JPG or GIF images, MPEG files, or other data that has already been storage-optimized, activating compression can have very little effect on throughput. This occurs because the compression algorithm can only achieve a small reduction in file size, which is offset by the processing overhead required for the sender to compress the file and the receiver to uncompress it. Therefore, you should determine if the traffic on your link is suitable for compression before you enable it.

The compression algorithm used is automatically negotiated by the DIVA LAN ISDN Modem and the remote site when the connection is established. The DIVA LAN ISDN Modem supports most popular compression standards, including: Ascend, MPPP, MS-STAC, STAC1, and STAC3.

You can enable/disable compression for each connection profile individually.

1.On the Configuration main menu, click Connection Profiles.

2.Click Edit for the profile you want to configure compression for.

3.Click Connection on the menu bar. You will see the following page.

4.Check the Compression box.

5.Click Finish.

6.Click Save.

7.Click Reset.