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Speed different downloading TCP vs UDP

I've Been Here Awhile



I have a data vendor that sends me stock market data via both UDP and TCP.  When sending UDP packets I have no issues and my speeds are good (30mbps +).  However, there are times when they send me TCP packets and my download speed appears to be limited to 12 mbps.


Of course my data vendor says that it is my ISP's issue (Rogers) and my ISP says its my data vendors problem.


Does anyone know how I can troubleshoot this to see why my speeds are slower when receiving TCP data.






Re: Speed different downloading TCP vs UDP


Good afternoon @fixplease!


Welcome to our Community! 


Speed variations between different types of packets can certainly lead to a frustrating experience, I know. In most cases, UDP will be faster than TCP but what you're posting here is quite a disparity in speeds.


Are you having issues with speeds on other websites or web based services or is the speed issue solely happening with this particular data vendor? Please let us know.




Re: Speed different downloading TCP vs UDP

I've Been Here Awhile

I believe I'm just having issues with just one data vendor.  I have a chart of my download when using TCP and it appears to be capped as it never spikes above 13 mbps.  Also when I run your typical Speed Tests - everything appears to be fine with my speed.


I have the IP address of the data server.


Is it possible that you could provide me with a phone number so I can bypass all the level 1 tech people and speak with someone who can do the proper testing to see why this is happening. I really want to avoid the level 1 stuff (which is really frustrating).

Re: Speed different downloading TCP vs UDP

Hello @fixplease,


There's no number to bypass our level 1 techs and in this case, you're going to have to work with this data vendor to find a solution as this would be outside of our regular scope of support.


If only this vendor is sending packets to you slowly, then there must be an issue with the routing on their end. If this was an overall TCP related issue happening on our end, you would be having TCP issues with other sites/vendors.




Re: Speed different downloading TCP vs UDP

I Plan to Stick Around
Facebook chat is your best bet for tech support. They're very good and far beyond what you get from phone in and the other chat.

That said, you're probably going to have to pony up and pay someone to do this analysis or invest your time in learning about networking.

Lots of other traffic is TCP. It's also got plenty of parameters and tuning characteristics.

You can try factoring out routers and stuff.

You could also download iPerf3 and run it against some of the public iperf servers. It will give you perf stats and you can cutomize the tests to be UDP, TCP, small packets, etc.

You could rent a cloud server or have a friend run iPerf3 for more control too. But just the client would be a start.

If you can show this data vendor that you can receive raw data from x y z sources via TCP just fine that should lend some credib itility to your case.

Latency can be an issue. If latency is high you might not have a larger enough buffer. Is this vendor far away? What latency is there compared to others? You can calculate the needed bandwidth delay product and again you get in to all the tuning that TCP has - it's a control protocol, after all. It could also be on their side - they could have too small a send buffer for the latency between you.
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