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[HELP] Very slow download, while upload is high

Posted: Tue Feb 14, 2017 4:44 pm
by zeropitarr
Hello,
I've installed VPN Server on Ubuntu.
VPN clients: iphone, Windows 8

Network Traffic Speed Test Tool:
without VPN:

Average Throughput in Download Direction | 36,882,029 bps| 36.88 Mbps
Average Throughput in Upload Direction | 4,933,468 bps| 4.93 Mbps

with VPN (L2TP or SSTP or SoftEteher VPN client with Local Bridge or SecureNAT):
Average Throughput in Download Direction | 300,533 bps| 300.53 Kbps
Average Throughput in Upload Direction | 4,792,693 bps| 4.79 Mbps


from VPN server to another server:
Average Throughput in Download Direction | 950,715,379 bps| 0.95 Gbps
Average Throughput in Upload Direction | 921,468,146 bps| 0.92 Gbps

CPU usage max 2%
Any ideas why download is so slow?

Re: [HELP] Very slow download, while upload is high

Posted: Tue Feb 14, 2017 10:51 pm
by zeropitarr
from another server to VPN server via VPN:

Average Throughput in Download Direction | 9,140,777 bps| 9.14 Mbps
Average Throughput in Upload Direction | 905,329,447 bps| 905.33 Mbps

At the same time dstat:

----total-cpu-usage---- -net/total- ---paging-- ---system--
usr sys idl wai hiq siq| recv send| in out | int csw
0 0 100 0 0 0| 0 0 | 0 0 |5686 12k
0 0 99 0 0 0| 597B 1631B| 0 0 | 366 710
0 0 99 0 0 0|6306B 6897B| 0 0 | 514 1242
0 0 99 0 0 0| 13k 14k| 0 0 | 656 1815
6 4 87 0 0 3| 85M 84M| 0 0 |5201 34k
6 4 88 0 0 2| 117M 116M| 0 0 |4836 47k
7 5 86 0 0 3| 114M 114M| 0 0 |5567 45k
6 5 87 0 0 3| 110M 110M| 0 0 |5589 46k
6 3 88 0 0 3| 114M 114M| 0 0 |4772 47k
6 4 87 0 0 2| 114M 114M| 0 0 |5274 47k
6 5 87 0 0 2| 117M 116M| 0 0 |5063 47k
6 5 87 0 0 2| 114M 113M| 0 0 |6064 48k
6 4 87 0 0 2| 114M 114M| 0 0 |5473 44k
6 4 88 0 0 2| 111M 111M| 0 0 |5026 46k
6 5 86 0 0 2| 117M 117M| 0 0 |5187 46k
6 4 88 0 0 2| 117M 116M| 0 0 |4672 48k
6 5 87 0 0 3| 112M 112M| 0 0 |5200 45k
7 5 86 0 0 2| 112M 111M| 0 0 |6414 44k
7 5 87 0 0 2| 117M 116M| 0 0 |4924 48k
2 2 95 0 0 1| 36M 36M| 0 0 |1927 17k

I've made separate tests for upload/download between servers via VPN:

only download

Average Throughput in Download Direction | 88,183,112 bps| 88.18 Mbps
Average Throughput in Upload Direction | 0 bps| 0 bps


only upload

Average Throughput in Download Direction | 0 bps| 0 bps
Average Throughput in Upload Direction | 910,387,042 bps| 0.91 Gbps

Why "Average Throughput in Download Direction" is very low still ?

Re: [HELP] Very slow download, while upload is high

Posted: Wed Feb 15, 2017 10:49 pm
by zeropitarr
**deleted** incorrect statement... download is always very low, compare to upload and non-VPN download

Re: [HELP] Very slow download, while upload is high

Posted: Wed Feb 15, 2017 11:15 pm
by zeropitarr
VPN Server ---- VPN Client

TrafficServer ---- TrafficClient - download ~88Mbps
TrafficClient ---- TrafficServer - upload ~ 8 Mbps

Why?

Re: [HELP] Very slow download, while upload is high

Posted: Thu Feb 16, 2017 12:34 am
by zeropitarr
I've removed Local Bridge on VPN Server.
Then tested connection between VPN clinets: client1<->VPN Server<->client2

Upload and Download were maximum.
So, the problem is with LocalBridge?!

Re: [HELP] Very slow download, while upload is high

Posted: Thu Feb 16, 2017 1:29 am
by highthroughputvpn
<zeropitarr>

What are you using as your traffic load between client and server?

What CPU is your server running?

I ask because I could not get that kind of speed running on very up to date hardware, details at:

http://www.vpnusers.com/viewtopic.php?f=7&t=7270

-----
Test 1: "vpnserver" and "vpnbridge" are Quad core i7-6700K @ 4.00 GHz on each end and with 1 GigE NIC hardware and 1 GigE switch. It appears I can max the tunnel out at ~850/850 Mbps bidirectional throughput. It does not appear to matter at all how many TCP sessions are active.
-----

Re: [HELP] Very slow download, while upload is high

Posted: Thu Feb 16, 2017 1:35 am
by zeropitarr
Q:What are you using as your traffic load between client and server?
A: traffic tool in vpncmd

Q:What CPU is your server running?
A:Intel(R) Core(TM) i7-6700 CPU @ 3.40GHz

...I could not get that kind of speed running on very up to date hardware...
A: I was able to get 0.95Gbps for upload only. Download is terrible


UPDATE:

I was able to achieve UP & DOWN :300-500Mbps by removing Local Bridge and enabling SecureNAT with DisableKernelModeSecureNAT = true.
CPU usage is very high as result =(

Any ideas how to fix Local Bridge ?

Re: [HELP] Very slow download, while upload is high

Posted: Thu Feb 16, 2017 1:47 am
by highthroughputvpn
No, apologies. :(

The async nature of your problem has me scratching my head.

For my traffic load I used the vpncmd tool as well as iperf on other dedicated machines.

iperf_machine----vpnSERVER----vpnBRIDGE----iperf_machine

When I started hammering the connection (iperf client and server on both iperf_machines pointed at each other, up and down, multiple streams) the CPU on both the vpnserver and vpnbridge spiked to 1 core at basically 100%.

I then moved the test to lesser hardware but more cores and throughput dropped to <500 Mbps, but it was always synchronous / even up and down, regardless of final throughput.

[scratches head]

I am even questioning the 0.95 Gbps upload as I could not get that on the bench with equal hardware.

Is "compression" enable anywhere? Compression killed my throughput testing down into the ~125 Mbps range.

Re: [HELP] Very slow download, while upload is high

Posted: Thu Feb 16, 2017 3:01 pm
by zeropitarr
I've found a solution.

I switched to Local Bridge with TAP. (I was using bridge with eth0)

Re: [HELP] Very slow download, while upload is high

Posted: Thu Feb 16, 2017 3:28 pm
by highthroughputvpn
Congratulations, I am glad you found a solution.

What OS are you on?

Thank you!

Re: [HELP] Very slow download, while upload is high

Posted: Thu Feb 16, 2017 3:42 pm
by zeropitarr
ubuntu 16.0.4.1 amd64

Re: [HELP] Very slow download, while upload is high

Posted: Thu Feb 16, 2017 4:31 pm
by highthroughputvpn
Thanks, same.

Re: [HELP] Very slow download, while upload is high

Posted: Thu May 16, 2019 2:06 am
by nakayama
I know this is an old topic, however, I found myself having the same problem and I was scratching my head for a while until realized that my VPS had a funny MTU value of 1986 for eth0 so I changed it to the standard 1500, then I also needed to change the value of MTU on SecureNAT to 1280, only then it worked at perfect speed.

Hope this helps someone else!

A. Nakayama

Re: [HELP] Very slow download, while upload is high

Posted: Wed May 22, 2019 12:09 am
by lawrence.eka
Hello, I have exactly the same situation. Tried to change MTU size to 1280 and gretap0 MTU size to 1500. No improvement. Any suggestion is welcome here. Thanks