Site to Site VPN True Connection Speed

Posted on 2011-03-01
Last Modified: 2012-05-11
Dear Experts,

I have a new project where i was ask to create a site to site vpn for offsite backups purpose (we already check online services and decided to go with the vpn choice)

I would like to know what will be my actual speed between the two sites,.and the benefits of choosing between two different types of connections.

On the main office i can have a 10Mbs Fiber or HSD TWC 50x5 and in the offsite location i will only have the 50x5 TWC connection option.

Would i benefit, or take adavantage of the fiber connection 10x10 even though the offsite connection is only 50x5 in other words when I am uploading data to the offsite connection will i see a troughout output of 10Mbs or it is going to be limited to the 5mbs in the 50x5 TWC connection.

The price difference between the Fiber and TWC is justify only if we can upload to the offsite at the 10Mbs throught output.

I thank you in advance for your expert opinion.



Question by:WilsonJ
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Assisted Solution

blakogre earned 100 total points
ID: 35012243
For what it's worth: VPNs create a lot of overhead.  Have you considered setting up an SFTP server at the remote site for backups instead?  Secure FTP has less overhead, and my improve your speed if that's an issue.  That's what we've implemented.

Good luck.

Author Comment

ID: 35012309
Thank you blakogre i will look into that solution. Do you happen to have more info on that, sounds interesting

Expert Comment

ID: 35012405
There are many solutions out there, some free.  Here's one commercial solution:

You'll also want a client that supports secure FTP.  Filezilla is free and supports SFTP.

SFTP, unlike FTP, encrypts the username/password and traffic -- so much of the same protection you get with a VPN, however, in my experience, it's faster due to less overhead.

You'd set up an SFTP server at one location -- remote, I presume, and with an SFTP client, upload the backup files.  You'll likely want to find a client that can schedule these jobs if you want to automate it.  My experience with free clients in that area is slim, as I didn't find any suitable in my research for one a year or so ago.

Instead of arranging a VPN tunnel between the two, you'd set up FWs appropriate on both sides to allow the SFTP client to talk to the SFTP server.  I'd suggest, also, limiting the IPs that can talk to the SFTP server for an added measure of security.l

So, it's pretty much just like using FTP, but secure instead of sending traffic in clear text.  Let me know if you have any other questions.
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LVL 79

Expert Comment

ID: 35013306
To answer the original question, from the remote site with 50/5 connection, that site will be "uploading" to the main office, so the transfer will be limited to max of 5Mb no matter how much bandwidth is available at the main office.
As blakagore pointed out, there is some overhead in the encryption over a VPN tunnel, so throughput will be less than that.

Author Comment

ID: 35013642
I know that the two sites will transmit data back and forth, and this logic  might just be wishful thinking, but I was just hoping that when the main office with 10/10 will be transferring or uploading to the offsite location with 50/5 the transfer rate will be somewhere closed to the 10's. Since technically the 50/5 is downloading from the 10/10.
LVL 79

Assisted Solution

lrmoore earned 100 total points
ID: 35013850
If the 50/5 site is actually downloading from the 10/10 site, then the potential throughput is better than the 5. I thought it was the other way 'round.
LVL 24

Accepted Solution

rfc1180 earned 300 total points
ID: 35020059
VPN overhead is negliable; depending on the encryption used, calculating the precise overhead added to user packets when they are transmitted over an IPsec VPN is complicated, particularly in relation to the overhead added by AH and ESP which can be between 1500 and 1600 bytes, considering the overhead of TCP/IP (40Bytes) this can put you at around 1360 of actual data payload assuming mss original mss is 1460. 5-10 percent of overhead, so you should see roughly around 9 Mbps (Worst case) on the 10/10 for upload, and 4.5Mbps on the 50/5 for upload. So as you can see, there is not much loss of available bandwidth (You also have to take into consideration, of normal network utilization too, so consider that.).


Expert Comment

ID: 35020113
For whatever reason: our VPN tunnel to our remote site xfers data about 50% slower than our SFTP.  Try both.  Do what works for you.

Author Closing Comment

ID: 35020333
Thank you all for your help and time,

I will go with the 10/10 in the main office and the 50/5 at the offsite location, i will also look into both solutions VPN and SFTP and pick the best one.

Best to all


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