- Network integrity: This refers to techniques such as Forward Error Correction (FEC) and Packet Order Correction (POC) that improve congestion and packet delivery challenges in the WAN itself. For example, if you are using MPLS or IP VPN as your WAN technology, you may be experiencing lost or out-of-order packets that are hurting application performance. By fixing these issues you will see significant performance improvements across the WAN even if the data is already compressed.
- Application/protocol acceleration: There are various techniques that can be used to overcome latency across the WAN due to TCP and other chatty protocols (eg CIFS). These techniques will work irrespective of whether the traffic is compressed or uncompressed.
- Data reduction: This is the one area that may be impacted by compression on the host device. Data reduction, which eliminates the transfer of duplicate data across the WAN, works best on uncompressed traffic when the WAN optimization device has full visibility into the entire data set. However, that is not to say that it still cannot provide value on pre-compressed data. The degree of performance gain will vary depending upon how compressed the traffic is and how much repetitive data is sent.
This was first published in February 2008