When communicating over satellite links, bandwidth is limited, latency is high as well as packet loss. FASP (and SSH) may need some adjustments on timeouts.
Satellite communication may incur extreme conditions such as:
Latency: 1000ms or more
Packet loss: 30%
The SSH server must be adapted to accept those network conditions:
Edit the file:
/etc/ssh/sshd_config, and set those parameters:
TCPKeepAlive yes ClientAliveInterval 600 ClientAliveCountMax 100 UseDNS no LoginGraceTime 2m
FASP settings on server side must also be adapted, execute these commands on server side:
asconfigurator -x "set_node_data;connection_timeout_sec,300" asconfigurator -x "set_node_data;session_timeout
If async is used, the following settings can be set:
asconfigurator -x "set_node_data;async_connection_timeout_sec,500" asconfigurator -x "set_node_data;async_session_timeout_sec,500"
"connection" parameters concern the timeout for the setup of the connection. "session" concern timeout of a session, once established.
A general rule with FASP as of version 3.7.2, when starting a transfer, is that the target rate shall not exceed ten time (10x) the actual bandwidth of the network. Otherwise, the protocol may try to accelerate too fast and cause excessive packet loss. A general rule is to set the target rate at around the expected available bandwidth, or slightly below.