live streaming kills internet

Discussion in 'MacBook Pro' started by royal shrimp, Jan 17, 2013.

  1. royal shrimp macrumors member

    Jul 20, 2011

    i have internet from comcast. i get 24mbps down, and 4mbps up. i have an Xbox and i like to live-stream. the problem is when I'm live-streaming at 2.5mbps, the ping goes from 10ms to over 400ms and all other computers have SUPER slow internet.

    my equipment:
    Retina macbook pro(where i stream from, wirelessly)
    Apple airport extreme (2.4ghz mode)
    motorola SB6121 modem.

    ANY AND ALL HELP is appreciated, this is stupid, it shouldn't be happening, and comcast technical support, as per usual, is no help at all

    thanks in advance, Phil
  2. throAU macrumors 603


    Feb 13, 2012
    Perth, Western Australia
    I guess you're on ADSL2?

    Are you actually SYNCING at 24 megabit? You will only attain such speed within 900m (err... 2700 feet) cable run from the telephone exchange.

    The chances are if you're like most ADSL2 customers, you're probably syncing somewhere around half that speed or less.

    So, say... 10 megabit.

    Streaming HD video will take maybe 4-6 megabit of that, leaving 4 megabit for everyone else.

    Also, the other traffic (like ping) will need to be inserted in between large packets on your network connection. So there will be additional latency incurred as even if you have capacity available, if a series of large DSL packets are already queued at either end, the small ping packet will need to wait for those to be transmitted.

    You may be able to tweak the ADSL settings with your ISP's web toolbox page (if they have one) for preference to lower latency vs higher throughput, and if you have a decent router you may be able to set up QoS tagging on your outbound traffic, but you're going to run into limitations inherent to ADSL at some point. Smaller MTU on your connection will help with latency.
  3. krravi macrumors 65816

    Nov 30, 2010
    I am afraid something is throttling your speed. Maybe the ISP or QoS settings on your router.
  4. takeshi74, Jan 17, 2013
    Last edited: Jan 17, 2013

    takeshi74 macrumors 601

    Feb 9, 2011
    How do you know this?

    It's likely that you're saturating your upload which will affect download. You'll find plenty of references out there on the internet as all this is due to the nature of TCP. I'm no network expert but here's my explanation based on my understanding (I recommend finding your own trusted sources and reading up for yourself):

    Downloading isn't simply a unidirectional transmission of data. The client performing the download has to send acknowledgements to the server. If the acknowledgements are delayed because the upload is saturated then the data being downloaded will be delayed as well.

    You say your stream is 2.5Mb but is that just the encoding rate of the stream itself? How much are you actually using with overhead? Additionally, you may not actually be getting the full 4Mb for upload. Have you actually tested with network monitoring tools to confirm the actual upload rate of your stream? Have you used network monitoring tools to determine what upload speeds you're actually getting with Comcast or are you just relying on the numbers for the tier of service that you're subscribed to?

    If you're saturating your upload it's not Comcast's fault. That is, unless you're not getting anywhere near 4Mb up.

    With Comcast (read the OP)?

    I'm not familiar with the Airport Extreme but I'm guessing it lacks the QoS to prioritize TCP ACK's which would probably help the OP.
  5. throAU, Jan 17, 2013
    Last edited: Jan 17, 2013

    throAU macrumors 603


    Feb 13, 2012
    Perth, Western Australia
    Comcast is not a global ISP, i have no idea what their connectivity services are. Where I live most ISPs offer multiple connectivity options...

    most of the crap I wrote probably applies anyway, except for the sync speed bit.

    Also - QoS only works on outbound traffic. Unfortunately, inbound, you'll get whatever scheduling the ISP sees fit.
  6. Mrbobb macrumors 601

    Aug 27, 2012
    From the information given, this should not happen. I suggest running a few tests to correlate the information.
  7. krravi macrumors 65816

    Nov 30, 2010
    I have the exact same equipment and ISP as the OP.

    See what the settings for IP V6 are in Airport Utility. Change it to "link local only"...Its under "Internet Options"

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