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I have a 1and1 Linux-based root server which I sometimes use to stream video to streaming video players at my house and at friends' houses. It has been working fine until a few days ago.

Now, it takes a long time to buffer the video, and then the video will only play for a few seconds and then it has to buffer again. My friend reports the same thing happening for them (trying to stream from the same machine). Suspecting slowness at the server, I used iperf to test the outbound speed of the server to a machine at work and I was getting 90Mbps... way fast enough. So, I tried streaming video from other sources to where I'm currently located, and those streamed just fine. In fact, I copied some of the same videos from my 1and1 server to a server with a cable-modem connection and I was able to stream from that server just fine, too. Weirder still, the transfer from the 1and1 server to the cable-modem'd server was the fastest of all.

So, I used wget to run some throughput benchmarks and here's what I discovered. Machine "A" is the 1and1 server. Machine "B" is a linux box I have right in front of me (on the same network as the streaming box I'm trying to use). Machine "C" is the spare server, connected to the net via cable-modem. From "A" to "B" gets about 40kbpbs (this is what's causing the long buffer times) From "A" to "C" gets about 2100kbps From "C" to "B" gets about 350kbps (probably limited by cable-modem's upstream limit, but still plenty fast and, indeed, I'm able to watch video streamed from C with not problems)

So, my question is... how do I make further progress in diagnosing what the deal is, here? The only explanation I have for this is that 1and1 is throttling the connection to certain IP's that have been using the network heavily. But... does anybody know if that's their policy? How would I prove, more-convincingly, that that's what's happening? Are there any other explanations for what I'm seeing (and are there ways to verify it)?

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What happened a few days ago? think back and you might find the root cause. –  Paul Ackerman Jul 13 '12 at 12:20

2 Answers 2

You're going to need to break out WireShark (or similar) and start looking at the hex dumps of the TCP datagrams. Make sure your MTU's match and look for TCP retransmissions. I'd also try tunneling everything through a SSH session or VPN if you suspect something is doing DPI along the way and throttling you.

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For something like streaming video a vpn or SSH would be a bad idea. You're already using UDP which is built specifically for speed (most likely anyways - do you really care about wasting cycles on that packet you should have received 2 seconds ago?). This is time sensitive, so anything that puts additional cycles into the mix will add latency, jitter, and lost packets. –  Matthew Jul 13 '12 at 1:37
    
Last I checked, 99% of streaming video is done over HTTP, which is TCP not UDP. But that's besides the point. My suggestion of using a VPN or SSH was a troubleshooting measure if he suspected someone fiddling with the packets via DPI. –  jamieb Jul 13 '12 at 2:27
    
I'd have to disagree, but I work for a cable company ;) –  Matthew Jul 13 '12 at 2:29
    
I've dabbled with wireshark before, but my expertise is not network protocols (ie, SYN packets, handshaking, etc.). I'm not even sure what layer I should be focusing on. Can you give me some ballpark ideas of what things I should be looking for if I'm being throttled or of there's some kind of weirdness between the two endpoints? –  Jemenake Jul 13 '12 at 23:28

First, get yourself a good packet analyzer (I highly recommend wireshark). Then on your server which is communicating to everyone else, start a packet dump on the correct network interface. Then start a session on one of the devices which you're having tons of errors with. That should give you a packet-level idea of what is going on. Also out of curiousity, are you using a linksys or cisco router? If so, they just pushed out a rather nasty firmware update a few days ago that affected a large number of them.

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