EdgeRouter: OpenVPN site-to-site performance

By | March 30, 2016

As a result of setting up my site-to-site VPN see this it is much easier to transfer things from one site to the other.

The questions that came to mind were:
What is the bandwidth of my VPN ?
What is the limiting factor ? My ISPs or the Edge Router ?

To answer to the above I used the iperf3 a tool that is already available on the EdgeRouter.
Site 1 that has an 500Mbps/25Mbps link will be used as the client.
Site 2 that has an 120Mbps/6Mbps link will be used as server.

I do this because I do not want to be limited by the 6Mbps uplink from Site 2. In this setup Site 1 pushes data onto the Site 2 so the limiting links will be the 25Mbps upload from Site 1 and the 120Mbps download on Site 2.
Note that Site 2 iperf3 must be executed first the Site 1 iperf3 command will start sending data.

Bellow the output from Site 2:


ubnt@ubnt:~$ iperf3 -s
Accepted connection from 10.99.99.1, port 44388
[  5] local 192.168.9.1 port 5201 connected to 10.99.99.1 port 44389
[ ID] Interval           Transfer     Bandwidth
[  5]   0.00-1.18   sec  1.00 MBytes  7.10 Mbits/sec
[  5]   1.18-2.22   sec  1.00 MBytes  8.06 Mbits/sec
[  5]   2.22-3.13   sec   896 KBytes  8.05 Mbits/sec
[  5]   3.13-4.20   sec  1.00 MBytes  7.88 Mbits/sec
[  5]   4.20-5.15   sec   896 KBytes  7.69 Mbits/sec
[  5]   5.15-6.25   sec  1.00 MBytes  7.63 Mbits/sec
[  5]   6.25-7.19   sec  1.00 MBytes  8.95 Mbits/sec
[  5]   7.19-8.23   sec  1.00 MBytes  8.10 Mbits/sec
[  5]   8.23-9.23   sec  1.00 MBytes  8.37 Mbits/sec
[  5]   9.23-10.20  sec  1.00 MBytes  8.64 Mbits/sec
[  5]  10.20-10.20  sec  0.00 Bytes  0.00 bits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth       Retr
[  5]   0.00-10.20  sec  9.75 MBytes  8.02 Mbits/sec    9         sender
[  5]   0.00-10.20  sec  9.75 MBytes  8.02 Mbits/sec              receiver
-----------------------------------------------------------
Server listening on 5201

Bellow the output from Site 1:


ubnt@ubnt:~$ iperf3 -c 192.168.9.1
Connecting to host 192.168.9.1, port 5201
[  4] local 10.99.99.1 port 44389 connected to 192.168.9.1 port 5201
[ ID] Interval           Transfer     Bandwidth       Retr
[  4]   0.00-1.03   sec  1.00 MBytes  8.18 Mbits/sec    5
[  4]   1.03-2.08   sec  1.00 MBytes  7.99 Mbits/sec    0
[  4]   2.08-3.07   sec  1.00 MBytes  8.41 Mbits/sec    0
[  4]   3.07-4.03   sec   896 KBytes  7.70 Mbits/sec    0
[  4]   4.03-5.01   sec   896 KBytes  7.50 Mbits/sec    4
[  4]   5.01-6.01   sec   896 KBytes  7.31 Mbits/sec    0
[  4]   6.01-7.03   sec  1.12 MBytes  9.28 Mbits/sec    0
[  4]   7.03-8.04   sec  1.00 MBytes  8.27 Mbits/sec    0
[  4]   8.04-9.07   sec  1.00 MBytes  8.14 Mbits/sec    0
[  4]   9.07-10.03  sec  1.00 MBytes  8.79 Mbits/sec    0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth       Retr
[  4]   0.00-10.03  sec  9.75 MBytes  8.16 Mbits/sec    9         sender
[  4]   0.00-10.03  sec  9.75 MBytes  8.16 Mbits/sec              receiver

iperf Done.

So the result is a bit over 8Mbps/8Mbps symmetric link.

In conclusion:
1. There is no limit due to the ISPs. 8Mbps is bellow both limiting links, the 25Mbps upload from Site 1 and the 120Mbps download on Site 2.
2. This is quite low bandwith, consistent with the fact that there is no hardware acceleration for OpenVPN site-to-site in EdgeRouter.
3. Strange that I did not notice a 100% CPU utilization on any of the routers, the highest peak went to 70% on the client site.
4. There are probably ways to improve this link.

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