What is the bottleneck in VPN connection?

Question

I have a LAN behind a Linksys RV016 Router. It is connected to the internet with DSL line with asymetric parameters 2Mbit download / 512 kbit upload.

In this LAN I have MS SQL server, and i want to connect to it remotely via VPN. To do this I use my RV016 router's PPTP function. Connection works fine, but ... little to slow.

And here is my question: what may be the bottleneck - is it only my DSL line's speed parameters ? Or may it be caused ALSO by router's hardware parameters (processor, RAM) ? In that case is it reasonalbe to set additional server VPN server inside the LAN, so that router only forwars communication on appropriate port and the rest is up to VPN server ?

How many users are you looking at sharing the connection with? Is it just you? — Jason Huntley, Mar 23 '12 at 18:24

score 4 · Accepted Answer · answered Mar 23 '12 at 18:25

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With 2048/512 kbit/s, you are most likely restricted by bandwidth, not by your routers hardware.

answered Mar 23 '12 at 18:25

Sven

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score 1 · Answer 2 · answered Mar 23 '12 at 18:27

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The speed will be limited to your upload connection, if you are trying to access the VPN DB over the internet. Also, there's a good chance the MySQL will be slightly slower if you have SSL-based VPN since each packet is encrypted, with additional bytes (size of enc) on each packet -- so it's transfering more data than if you are using non-encrypted connection.

answered Mar 23 '12 at 18:27

Ben Ashton

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MS SQL, not MySQL. Same problem either way, of course. – mfinni Mar 23 '12 at 18:32

score 1 · Answer 3 · answered Mar 23 '12 at 19:04

In addition to what others already have said, if you download a file over the vpn, the file will get in essence first go downstream on your DSL and then upstream.

The download capacity will be a bit below the maximum upstream bandwidth due to the double (assumed) TCP overhead, and GRE encapsulation. The RTT will probably cause all downloads to start slower aswell.

mfinni · Answer 4 · 2012-03-23T18:33:39.047

Yup, the slowdown is almost definitely due to your bandwidth, and (remotely possible) any traffic-shaping that your ISP might be doing on inbound traffic.
It's possible that the router might be doing too much, but unless you're doing a lot of VPN connections, or doing something like BitTorrent, it's probably not the problem.
By "connecting", do you mean using RDP, or something that actually makes SQL connections, like SQL Management Studio or osql or ADO/ODBC/etc? The latter will always be slower over a WAN link than a LAN, period.
This question should have been posted to SuperUser. SF is specifically not for home users, home servers, etc. Please read the FAQ. Your question will move automatically when it's gotten enough close/move votes.

This is not a home network. – malloc4k Mar 23 '12 at 22:47 — malloc4k, Mar 23 '12 at 22:47

What is the bottleneck in VPN connection?

4 Answers4