On 06/08/2018 05:47 AM, Gena Makhomed wrote:
Yes, I see Bandwidth 99.1 Mbits/sec and Bandwidth 99.0 Mbits/sec
But I need to see the same excellent values for TCP protocol too.
This is possible with OpenVPN at all?
What can be tuned in OpenVPN or in operating system?
What is the root cause of such very low network throughput values
then TCP-based protocols are used on top of OpenVPN connections?
Gena,
Decent encryption makes the data payload bigger and then there is the
additional header and protocol overhead. More data means not just more
packets to send but also more likely dropped packets and resends etc. So
it isn't possible to be as fast as without decent encryption. There is
no free lunch. I haven't kept up with openvpn enough but in general
principle, the degree to which you can relax the encryption (make it
less strong) will be the degree to which you can keep the payload and
overhead small. The extreme being where no encryption exists at all and
the "vpn" server becomes merely a proxy server. I bring this up because
if the endpoints have low processing power then the computation of the
encryption and decryption could play a role in the throughput also.
Lastly, if you don't have your openvpn MTU set properly smaller to allow
for the openvpn packet overhead then you can end up creating packets on
the underlying UDP layer that end up getting fragmented which increases
overhead and decreases throughput.
Sorry if this reads sloppy like I haven't had enough coffee yet. This is
because I most certainly have not had enough coffee yet! ;)
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