Network Requirements

HVR’s network communication initiated through the HVR Remote Listener is optimized for high latency, low bandwidth network configurations, so it is recommended to use it, especially in Wide Area Network (WAN) scenarios. HVR is extremely efficient over WAN and uses the minimum possible bandwidth. This is because HVR sends only changes made to a database, not the entire database. It also bundles many rows into a single packet and it does very few network roundtrips. Its compression ratio is typically higher than 90 percent. Compression ratios vary depending on the data types used but may be as high as 10 to 1. This compression ratio is reported by Capture jobs and can be used to accurately determine the amount of bandwidth used. The ratio is shown in the HVR GUI by clicking on Statistics.

To measure HVR's network bandwidth usage, we recommend using command netstat -i, which runs on Linux, Unix, and Windows.

Refresh and row-by-row compare may use a lot of bandwidth in a short period of time, because a lot of data is transferred between systems. If the HVR protocol is used, then network communication is optimized relative to using database connectivity across the network.

HVR will always try to transport the data as quickly as possible and may be using all of the available network bandwidth. Action LocationProperties with options /ThrottleKbytes and /ThrottleMillisecs can be used to prevent HVR from using all available network resources if the available bandwidth and one point in time would not be sufficient to keep up with the transaction volume.