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Configure Burst Size for EthernetConnect



we have a 1Gbit EthernetConnect from our provider between two locations. Site A has a FortiGate 100E and Site B has a FortiGate 300E.

Unfortunately, we have the problem that we have very poor bandwidth performance on the line. Via iperf3 I measure ~ 300Mbit (tcp) but almost the 1Gbit (udp).


Now I made a call to my ISP and he tells me that I should configure EBS and CBS to 60.000 - only the question is, what does he mean exactly or how can I store this on the FortiGate?



Hi @FortiGateAdmin 


Thank you for contacting Fortinet community.


The ISP might be suggesting to use traffic shaping to prioritize traffic. As you are not prioritizing any specific traffic and getting less throughput generally, I'm not sure if this will help in your case. However, you can review the following links for detailed explanation.


iPerf throughput is affected by TCP window size and may give a wrong impression sometimes. Please modify TCP window size based on the iPerf documentation. It is calculated as a bandwidth x delay and is defined between 2 and 65,535 bytes. Please refer to the iPerf documentation.