This article describes how to fine-tune the TCP buffer size.
Scope
FortiWeb.
Solution
FortiWeb provides a way to improve TCP transmission performance by adjusting the buffer parameter of TCP connections through the CLI over high-bandwidth, high-latency networks. When dealing with large file transmissions (usually larger than 150MB) or traffic congestion between FortiWeb and backend servers, clients may experience poor TCP performance.
To avoid it please execute the below commands.
config system network-option set tcp-buffer low|pressure|High end
To control memory usage, the tcp-buffer option in the system network option defines the TCP_mem variable, which is made up of three values measured in memory pages:
Low: This value sets a threshold for low memory usage. When memory usage is below this point, the TCP stack does not adjust memory usage by interacting with TCP receive and send buffers for the sockets.
Pressure: This value tells FortiWeb to start pressuring memory usage down when it reaches a certain point. Memory pressure is continued until the memory usage enters the low threshold. During this time, the TCP receive and send buffers for the sockets are adjusted to maintain the default behavior of the low threshold.
High: This value sets the maximum memory pages FortiWeb may use. If this value is reached, TCP streams and packets are dropped until FortiWeb starts using fewer memory pages again.
Note: Modifying the TCP buffer size may increase device memory utilization, but the memory will be released after the proxy processes the data. Changing the TCP buffer can also optimize device throughput.
