How can I find out why traffic isn't being compressed?

Products

• PacketShaper

Issue/Introduction

When I compare the Compression Summary reports, with and without the include compressible traffic checkbox enabled, I see that some of my traffic isn't getting compressed.

Resolution

Xpress does not attempt to compress all traffic. Because PacketShaper is application intelligent, it is able to identify each traffic flow and compress only the flows that are likely to achieve useful gains. Previously compressed traffic (such as streaming media) and encrypted data (such as Telnet-Secure, FTP-Cmd-Secure, IMAP-Secure) are examples of non-compressible traffic.

There are other reasons that traffic may not be compressed, and in Xpress 8.0 there is a graph that provides a breakdown of these reasons. To see this graph:

1. On the Compression Summary page, select the include non-compressible traffic in graphs and data checkbox.

2. Click update.

3. Click the Non-compressible traffic breakdownlink.

A new window opens, displaying the Non-Compressible Traffic graph for Outbound traffic. This line graph indicates the amount of traffic that was non-compressible due to each of the following reasons:

Compression Disabled - Compression was not enabled (for example, compression was intentionally disabled for a particular tunnel).

Traffic Policy - The traffic was classified as a non-compressible service, compression was disabled for the service or class, or the traffic was broadcast or multicast (Note: Multicast traffic won't be compressed unless the Class D addresses are added to remote and/or local host lists.)

System Availability - There was insufficient compression memory to tunnel the traffic or the CPU was too busy.

No Tunnel for Host - Hosts were restricted from using compression (tunnel discovery host), partners were excluded from using compression (tunnel discovery partner), a tunnel partner wasn't found, or hosts were not discovered.