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I've got a Macbook Pro connected to an Apple Time Capsule wirelessly. It's using 802.11ac and the detailed view of the wireless connection shows this:

enter image description here

The transfer speed is typically being shown in the range from 800 to 1000+ Mbits.

I've also got a Windows 10 PC plugged directly into the Time Capsule. These should be gigabit ports.

I ran a iperf3 test between these machines and these are the results:

C:\Users\roran\Downloads\iperf-3.0.11-win64>iperf3.exe -c 192.168.200.5 Connecting to host 192.168.200.5, port 5201 [ 4] local 192.168.200.33 port 53093 connected to 192.168.200.5 port 5201 [ ID] Interval Transfer Bandwidth [ 4] 0.00-1.00 sec 27.9 MBytes 234 Mbits/sec [ 4] 1.00-2.00 sec 27.1 MBytes 227 Mbits/sec [ 4] 2.00-3.00 sec 26.4 MBytes 221 Mbits/sec [ 4]
3.00-4.00 sec 25.2 MBytes 212 Mbits/sec [ 4] 4.00-5.00 sec 27.2 MBytes 228 Mbits/sec [ 4] 5.00-6.00 sec 25.2 MBytes 212 Mbits/sec [ 4] 6.00-7.00 sec 25.8 MBytes 216 Mbits/sec [ 4]
7.00-8.00 sec 26.4 MBytes 221 Mbits/sec [ 4] 8.00-9.00 sec 28.4 MBytes 238 Mbits/sec [ 4] 9.00-10.00 sec 25.8 MBytes 216 Mbits/sec - - - - - - - - - - - - - - - - - - - - - - - - - [ ID] Interval Transfer Bandwidth [ 4] 0.00-10.00 sec 265 MBytes 223 Mbits/sec sender [ 4] 0.00-10.00 sec 265 MBytes 223 Mbits/sec receiver

iperf Done.

I'm copying a large file (160gb) from the mac to the pc and I'm seeing transfer speeds inline with the results from iperf3. I'd expect that to be higher since this should be the only traffic on the network and 800 Mbytes/s (the wireless TX rate above) should be 100 MB/s.

Also, I'm seeing these odd pauses in the transfer speed where it dips down to 0 bps and then climbs back up. I think this might be on the mac side since it seems to correspond to the mac pausing for a second. Here's the perf monitor in windows:

enter image description here

Am I right in thinking this is a bit slow? Or, is this pretty much to be expected?

Another thing of note is that the mac is transferring from an SSD while on the Windows PC data is going to a USB2 external drive.

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Just because you are using gigabit Ethernet doesn't mean your switch is capable of actually switching packets that fast.

Look for info on what to expect from your switch. Maybe compare the speed you get with a direct crossover cable.

The performance of your hardware and software on Mac and pc should not be taken for granted either.

USB dives are not as fast as you might be expecting. See What's the maximum typical speed possible with a USB2.0 drive?

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  • Is it safe to interpret this comment as "Your transfer speed is not entirely unreasonable"?
    – Doug Hughes
    Oct 18 '15 at 16:28
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    I think if you get better performance it won't be a lot better. Your usb dive controller is probably the limiting factor
    – mc0e
    Oct 18 '15 at 16:29
  • A very simple test shows that you're right that the USB drive / controller was a limiting factor. I'm trying copying the same file to a non-usb drive and it's about 3x faster. That's a huge difference. Enough to make me not worry about this any more. Thanks!
    – Doug Hughes
    Oct 18 '15 at 16:33

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