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For some reason, I was downloading something at 300kb/s. Then I turned my VPN on and the download speed jumped up to 1.3mb/s.
Why is this? Is it because the VPN server reduces the jumps between me and the server?
RazeLegendz
Posted 2016-04-28T21:55:17.107
Reputation: 255
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There are a few possibilities - unfortunately, the number of hops is irrelevant.
The first is compression - if the data you were downloading is uncompressed, and your VPN offers compression then this could explain it - however most files transferred are likely to be compressed, so this is not as likely as it would seem at first blush.
The second and third options are related, and have to do with your ISP's connectivity and restrictions. Your VPN has found a faster path to the destination data then directly - which could be because -
The ISP has multiple connections, and the direct connection to the data is constrained. The VPN goes across a different connection, which in turn has better connectivity to the source of the data you are pulling, thus you are routing round the congestion.
The ISP is shaping certain kinds of traffic - possibly by type or destination or both - it could even be by content/payload - but that is less likely. By using a VPN, your traffic is being given priority or not being capped, so you are getting better speed.
There are some other possibilities, but these are again less likely - it could be that the VPN is using UDP while your download would typically use TCP, and different optimisations (MTU for example) are allowing better use of your connection. Again, this is possible, but unlikely - chiefly because you would expect either a much smaller or much greater difference in speed.
davidgo
Posted 2016-04-28T21:55:17.107
Reputation: 49 152
You beat me to the punch :-) - but I actually like your answer better. – LSerni – 2016-04-28T22:14:23.683
3Does it really make sense for an ISP to give VPN traffic a free pass given it's a tunnelling protocol? I would expect everything to be rate-limited by default and only some services to be prioritized by whitelist. – Thomas – 2016-04-29T02:37:32.637
4@Thomas A lot of ISPs use transparent proxies for certain things like HTTP. The idea is that they can cache results to speed up page fetches and reduce bandwidth requirements... which of course does nothing positive for dynamically generated content. What ends up happening is they introduce additional pointless delays for most modern content. There's no point trying to proxy or cache VPN traffic so it doesn't get the additional delays. – Corey – 2016-04-29T05:11:17.543
3@Thomas the problem is that VPN traffic is not easily identifiable - it can be disguised to look like other kinds of traffic (including VOIP - which requires low latency), and also corporates use VPN's a lot, so they may get a better class of service. Also, Most VPNs use UDP rather then TCP which is used by most download protocols. Its A LOT easier to reduce performance of a TCP connection then a UDP connection without causing issues as TCP takes a hint to slow down when packets are dropped (by design), while UDP doesn't. – davidgo – 2016-04-29T05:32:54.177
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It's also possible that the server on the other end is throttling based on your ISP: http://www.usatoday.com/story/tech/news/2016/03/25/netflix-throttling-video-t-verizon-users/82248762/ is a recent example of this (people were blaming Verizon/AT&T for slow Netflix, but it was actually Netflix throttling on purpose). I don't see in that article, though, whether it was based on IP (which would affect people connected to a hotspot, but not the device on a VPN), or something on device detecting the carrier.
– childofsoong – 2016-04-29T17:50:10.597Number of hops won't change the download speed as OP mentions it, but it can improve latency. WTFast is often used for gaming because of this. – Kat – 2016-05-05T19:31:34.920
WTFast is a vpn service. Its not the number of visible hops that improving latency, its the shorter route facilitated by the VPN as per my earlier comment. – davidgo – 2016-05-06T06:08:01.200
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Relevant: VPN with Encryption gives twice the download speed?
– DavidPostill – 2016-04-28T22:02:37.317Idea: What is your download/upload speed according to the contract with your ISP? Maybe they limit the download speed and since VPN runs encrypted they can not verify that and the limitation rule is different – Divin3 – 2016-04-28T22:03:22.853
My ISP speed is 100mb/s or about 13 megabytes/s. Fastest download speed I've had with it was 10 megabytes/s. I don't think they're limiting me, just that the server is far away, and the VPN server I'm connected to might be closer. I don't know too much about networking, so this might be inaccurate. – RazeLegendz – 2016-04-28T22:07:16.800
yup, VPN can't speed things up. It will always cause a higher latency because it has to go trough (at least one) extra gate(s) to get to the location. Imagine yourself as point A, your VPN server at point B, and the server where you download the file from as point C. You connect A, B and C together with lines. There is place where you can place point B to make the distance between A and C shorter. – Divin3 – 2016-04-28T22:12:15.413
4@Divin3 - It is entirely possible for a VPN to speed things up and reducing latency. I've covered the speedup in my answer. In addition to that, a VPN can reduce latency (a bit, by compression) or a lot (via an alternate path - particularly where load balancing is being done to remote locations where cables are constrained and supplemented with Satellite capacity - less common now though). I also note that latency on a small link can vary significantly with usage. If VPN endpoint is on a router in the path, latency does not always go through an exfra gate - common on corporate VPNs – davidgo – 2016-04-28T22:28:31.263
1@davidgo - by latency I mean the response time. For example if you play an online game the latency can't really be lower if you use any sort of VPN. The download/upload speed (bandwidth) is a different question. – Divin3 – 2016-04-28T22:45:59.553
3@Divin3, the latency could certainly be lower depending on how the ISP treats certain types of traffic. Also as davidgo pointed out, it's entirely possible the VPN takes a different/better path. It's not impossible by any means... I've utilised VPNs to reduce latency before, it's uncommon but not unheard of. – user161778 – 2016-04-28T22:56:05.617
2@Divin3 - I understand latency, and was commenting on that. A typical satellite connection is about 600ms, the same over cable could be less then 120ms. Also google Buffer Bloat - something that alternative paths can also route around sometimes to reduce latency. – davidgo – 2016-04-28T23:36:33.743
@davidgo - So you mean the best path isn't always selected by the routing process? This is what they taught me at the university. :-) Lets say we have point A, B, C. We want to reach from A to C. Even if the fastest path to arrive there would be trough B, wouldn't that be automatically selected as the optimal route? – Divin3 – 2016-04-29T02:07:56.360
1One of the things you learn over the years is that many of the things they teach you at university are gross oversiplifications of reality. – plugwash – 2016-04-29T03:42:03.130
1@Divin3 Absolutely the best path is not always selected by the routing process - in fact, it can be very difficult to force routing to take the best path in some cases - with all kinds of tricks being used. Whoever taught that to you is in dire need of correction. (Another way to think about it is "best" depends on your goal - which is not something a router can detemine by itself) – davidgo – 2016-04-29T03:49:14.177
@davidgo - thanks for the information, I will do some research about routing. If you have any good articles about this topic, I would be thankful if you could give me a link. – Divin3 – 2016-04-29T03:53:06.663
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@Divin3 - Sorry I can't provide articles on the topic. My experience comes from building ISP's 15-20 years ago ! Some useful links I've found for you include : http://bandwidth-bandits.blogspot.co.nz/2009/05/how-router-makes-routing-decisions.html and http://www.enterprisenetworkingplanet.com/netsp/article.php/3615896/Networking-101-Understanding-BGP-Routing.htm
– davidgo – 2016-04-29T05:29:16.487@RazeLegendz give me your VPN provider name? because i also want to try it in my Home. – Akshay Pethani – 2016-04-30T11:01:03.757
Possible duplicate of VPN with Encryption gives twice the download speed?
– Moshe Katz – 2016-05-02T18:54:18.153@Divin3 I use CyberGhost VPN and Verizon Fios Internet – RazeLegendz – 2016-05-09T02:15:53.843