Why is 802.11n network so slow?

Discussion in 'Mac Accessories' started by GoatBnnn, Apr 5, 2008.

  1. GoatBnnn macrumors newbie

    Mar 18, 2008
    Hey everyone. I recently bought a MacBook Pro and an Airport Extreme. I have connected a HDD to the Airport Extreme, and have set it to be the backup location for Time Machine.

    Everything is working well, except the maximum speed of my network seems to be around 2MB/s. Clearly, 802.11n should be able to go much faster. I have been tinkering around a little over the past few hours, and a few times I have gotten the network to go really fast, a gigabyte in a few minutes...but I cant sustain that speed.

    Also, every time I look at an application that can show me the network speed, I see a drop in the speed of the network. Is OSX throttling the file transfers?

    Please let me know what you think. Thank you!
  2. pjarvi macrumors 65816


    Jan 11, 2006
    Round Lake, IL
    I don't know if this is the cause, but you pointing out that you're maxing out around 2MB reminded me that the default multicast rate is set to that. I have no clue if it is actually causing your problem, but just thought I would mention it. It's buried in the wireless settings (advanced section IIRC).
  3. GoatBnnn thread starter macrumors newbie

    Mar 18, 2008
    Actually, this was the problem initially, but I figured that one out pretty quickly. The 2mb/s I speak of is coincidentally the same speed, but its not capped because sometimes it seems to copy data at 100+mb/s, just cant keep that speed... :confused:
  4. iPhil macrumors 68040


    Yeah don't have any b/g wifi devices to the network....

    How to solve this problem is in the settings of Airport extreme go to: (Radio mode) change from 2.4 to 5.0 Ghz..
  5. Evangelion macrumors 68040

    Jan 10, 2005
    I bought and installed Time Capsule yesterday, and configured a N-only network alongside my existing G-network. The initial Time Machine-backup (over WiFi) is proceeding at about 700KB/sec.... When I tried it with gigabit ethernet, it was about 2-7MB/sec.

    Now, is it the network that is slow, or Time Machine?
  6. LouisBlack macrumors 6502

    Jun 21, 2007
    Balham, London
    I don't think Time Machine is helping. My initial back up took hours over USB2. It took about 6 hours to back up 200 gigs. I know USB isn't consistant over long transfers but it's not that slow. When transferring that data back manually, it was much faster.
  7. Anonymous Freak macrumors 601

    Anonymous Freak

    Dec 12, 2002
    Well, the drive software (AirPort Disk,) on the original AEBS-n was painfully slow, even on the Gigabit model. (The 100 Mbps limitation on the original release didn't matter. Even over Gigabit, it's slow transferring to/from a USB-connected hard drive.)

    I was hoping that Time Capsule has a 'native' SATA controller, and doesn't just make use of an internal SATA-to-USB adapter, but I haven't yet seen any corroboration; and reports like this make me think that Time Capsule is just as slow.

    But, yeah. 2 MB/s sounds about right. Sucks.

    But, that is only for transfers to/from the AEBS/TC-connected hard disk. For local network transfers, you should be able to get about 12.5 MB/s. (12.5 Megabytes/s = 100 Megabits per second, which is the realistic real-world throughput of "300 Mbps" 802.11n.) Again, if you aren't connecting multiple Gigabit computers, the 100 Mbps limit on the original release AEBS-n isn't a big deal.

    And if you are measuring the speed to some random computer on the Internet, instead of purely local-network, then the speed is completely dependent on your Internet connection.

    For example, I have Comcast's "high end" cable internet, which means that on a good day, I get a "PowerBoost" of up to 20 Mbps download, 2 Mbps upload. More often, I get about 10 Mbps download, 1.5 Mbps upload sustained. Note that 2 Megabytes per second is 16 Megabits per second. So if you are using a tool that is measuring your Internet connection, instead of your local connection, then you're getting a decent 16 Mbps Internet connection.

    Really, the best way to measure your wireless speed is between a wireless computer sitting about three feet away from the base station, to a computer plugged in via Gigabit Ethernet on the base station. Make sure you are copying from a fast internal drive to a fast internal drive, to weed out any USB or FireWire slowdowns. (Although both interfaces are faster even than 802.11n's theoretical maximum of 300 Mbps, so it shouldn't really matter.)

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