Achieving Maximum Throughput for File Transfers using Acceleration

You can achieve maximum throughput using file acceleration when transferring large files on high latency connections such as the ones between inter-continental and cross-continental locations with the following techniques:

Utilizing the network bandwidth to the maximum by varying the number of channels.

Adjusting the Minimum Fast Speed and the Minimum Slow speed based on the one channel test.

Adjusting the Channels Ramp Up value based on the IN/OUT channels set, and the performance of file acceleration.

Note:
These guidelines are applicable (have been tested) only for the inbound file transfer scenario in ActiveTransfer Server and in the case of file download using ActiveTransfer web client.

The acceleration parameters and their roles are listed in the table below:

Acceleration Parameter	Description
Basic Settings:
IN Channels	Indicates the maximum number of inbound channels that can be opened in parallel to transfer one file.
OUT Channels	Indicates the maximum number of outbound channels that can be opened in parallel to transfer one file.
Advanced Settings:
Stability Interval	The time to monitor a stable average speed before adding new channels. By default, 1 channel is added after the speed is stable for 5 seconds.
Channels Ramp Up	Number of incremental channels added at one shot. Default is 1.
Minimum Fast Speed	Minimum speed that each channel should reach before a new channel can be added. Default value is 100Kb/sec.
Minimum Slow speed	Speed below which the channels are removed. By default, one channel at a time is removed at every interval 50Kb/sec.
Speed Threshold	Threshold speed to be reached before a new channel is added. Default value is 60%.

Setting Up the Channel Count

The IN and OUT channel counts are tuned based on the utilization of the hardware resources on the server machine. For example, in a network with 100 Mbps bandwidth and 150 ms latency, if we see a transfer rate of 48 Kbps with one channel, the network utilization is 0.5% of 100 Mbps. In this case, you will take around 400 minutes to transfer a 1 GB file. One solution to this issue is to set the IN channels to 200. This will increase the combined transfer rate to 9.37 Mbps (48 Kbps x 200 channels). With this new setting for IN channels, you will be able to transfer a 1 GB file in about 1 minute 49 seconds.

Increasing/decreasing the Minimum Fast Speed

You should make a note of the average transfer speed per channel and use that information to set the Minimum Fast Speed.

Increasing/Decreasing the Minimum Slow Speed

You should make a note of the minimum transfer speed per channel and use that information to set the Minimum Slow Speed.

Setting the Channels Ramp Up

You should decide on the Channels Ramp Up setting based on the number of IN/OUT channels. For example, if you set the IN Channels count to 100 channels and the Channels Ramp Up count to 10 for a file transfer, the channel count is ramped up in multiples of 10 which will help in achieving the required speed quickly. On the other hand, if for a IN Channels count of 20, if you set the Channels Ramp Up count to 10, you may not get the required speed. This setting might slow down the file transfer instead. A Channel Ramp Up value between 2- 4 channels will provide better results here.