Link Aggregation in Action

In order to get an idea of how link aggregation really helps, we first set up the NAS with just a single active network link. The first set of tests downloads the Blu-ray folder from the NAS starting with the PC connected to port 3, followed by simultaneous download of two different copies of the content from the NAS to the PCs connected to ports 3 and 4. The same concept is extended to three simultaneous downloads via ports 3, 4 and 5. A similar set of tests is run to evaluate the uplink part (i.e, data moves from the PCs to the NAS). The final set of tests involve simultaneous upload and download activities from the different PCs in the setup.

The upload and download speeds of the wired NICs on the PCs were monitored and graphed. This gives an idea of the maximum possible throughput from the NAS's viewpoint and also enables us to check if link aggregation works as intended.

The above graph shows that the download and upload links are limited to under 1 Gbps (taking into account the transfer inefficiencies introduced by various small files in the folder). However, the full duplex 1 Gbps nature of the NAS network link enables greater than 1 Gbps throughput when handling simultaneous uploads and downloads.

In our second wired experiment, we teamed the ports on the NAS with the default options (other than explicitly changing the teaming type to 802.3ad LACP). This left the hash type at Layer 2. Running our transfer experiments showed that there was no improvement over the single link results from the previous test.

In our test setup / configuration, Layer 2 as the transmit hash policy turned out to be ineffective. Readers interested in understanding more about the transmit hash policies which determine the distribution of traffic across the different physical ports in a team should peruse the Linux kernel documentation here (search for the description of the parameter 'xmit_hash_policy').

After altering the hash policy to Layer 2 + 3 in the ReadyNAS UI, the effectiveness of link aggregation became evident.

In the pure download case with two PCs, we can see each of the PCs getting around 800 Mbps (implying that the NAS was sending out data on both the physical NICs in the team). An interesting aspect to note in the pure download case with three PCs is that Machine 1 (connected to port 3) manages the same 800 Mbps as in the previous case, but the download rates on Machines 2 and 3 (connected to ports 4 and 5) add up to a similar amount. This shows that the the network ports 4 and 5 are bottlenecked by a 1 Gbps connection to the switch chip handling the link aggregation ports. This is also the reason why Netgear suggests using port 3 as one of the ports for handling the data transfer to/from the link aggregated ports. Simultaneous uploads and downloads also show some improvement, but the pure upload case is not any different from the single link case. These could be attributed to the limitations of the NAS itself. Note that we are using real-world data streams transferred using the OS file copy tools (and not artificial benchmarking programs) in these experiments.

Introduction and Benchmarking Setup The Promise of Gigabit Wi-Fi and Concluding Remarks
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  • ganeshts - Thursday, December 31, 2015 - link

    Yeah, 1024-QAM was not working irrespective of where I placed the bridging router. I believe Tim @ SmallNetBuilder was unable to make it work too. Admittedly, it requires almost ideal conditions to kick in, but, I think Netgear / Broadcom has plenty to fix in the firmware.
  • melgross - Thursday, December 31, 2015 - link

    I really hate to break into comments on something else here, but there's nowhere else to really express my frustration.

    I've been seeing, and reading, a lot of reviews here during December, and I'm still waiting for the review of the ipad Pro, which came out some time ago now, and was promised for December. Well, here we are, and it's the last day in December, and where is it? Quite frankly, I've seen reviews of more than a few trivial devices that few people will be interested in, going by the small number of comments on them. I don't ever remember a review taking so long to come out, particularly since the site has has a unit, and came out with some tested specs over a month ago!

    I'd like to know what the problem is here, as every other site has had their reviews in over a month ago, including some good, in depth ones. What's the excuse for the hangup? People here, whether they want Apple's products, or don't want them, like to read the reviews, and comment.
  • Pissedoffyouth - Thursday, December 31, 2015 - link

    What the hell are you talking about? They did an ipad pro review LAST MONTH:
  • lagittaja - Thursday, December 31, 2015 - link

    Ahem. That's NOT a review. It's a preview (says so in the title) with a couple of benchmarks..
    And if you'd even bother reading the preview, it specifically says in the end of pg2:
    "Anyhow, we’ll be back later with a full review of the iPad Pro, including the pros and cons of Apple’s first large-format, productivity-oriented tablet, and a full breakdown of the A9X SoC. So until then stay tuned."
  • dsumanik - Thursday, December 31, 2015 - link

    I disagree dave, the reviews used to be worth waiting for but now they are seriously biased and sales oriented. Honestly purch has turned this into whole site into a viral marketing platform. Recent lame reviews:

    -The ASRock Z170 Extreme7+ no testing of triple m.2 performance
    -gigabyte-z170x-gaming-g1 : no quad SLI or thunderbolt tests

    And surprise surprise we have issues with this board already:

    Now to be fair gigabyte is aware of the issues and will almost certainly fix them, but the point is if AT had simply tried plugging in a few different memory modules, they would have discovered the board has problems with XMP profiles.

    But they didnt check. They didnt check basic memory compatibility. like wtf.

    And they didn't test out quad SLI, even though its advertised in the article title. I am sorry to be so negative but im going to keep posting these comments in hopes AT cleans up their act, it's getting ridiculous.

    The iPad pro review you are waiting for so desperately is going to come out overwhelmingly positive, and skip over the fact that the thing is too big, isn't able to increase productivity (except certain scanarios with graphic artists) and requires you to charge the 100 dollar pencil from the port in the bottom, making the device completely unusable, or storable while the pencil is charging.

    If you want to know what an iPad pro is like, it's EXACTLY the same as an ipad2 with a bigger screen and an awesome, overpriced stylus that has no eraser and is a facepalm to charge.

    Just getting photos into an editing app on iOS is such a PITA, and you wind up with mutiple copies in your camera roll and the app itself etc. Organizing is a nightmare, and the only way around it would be to use icloud photos, which you have to pay for.

    By the time you get an image loaded and start mucking about with the stylus, buddy next to you on a 2012 mid level PC has imported, tagged, organized, retouched 500+ photos (using sync settings) in lightroom and is about to go have his lunch break, it’s rediculous. Ph and he backup up the catalog, in case a problem occured.

    The fact, that even loading a camera raw file onto an ipad converts it to jpeg, is a fail right there.

    The device is supposed to be for content creation and editing, but you cant even choose an export format or edit a master file directly.

    Can anyone here point out a negative Apple review posted on this site ever???

    Just one.
  • melgross - Thursday, December 31, 2015 - link

    What a bunch of BS from you here. If you don't like a review, it's biased. Little minds think that way, particularly if it's a review of a company's products that you've decided you don't like, even if you know almost nothing useful about them.

    That opinion of yours just shows your own strong biases and negativity.
  • melgross - Thursday, December 31, 2015 - link

    I should have also pointed out that s it's pretty obvious that you've never even used the device, as you don't seem to understand it, or how people use styluses.

    Possibly, you should go on a number of artist sites and see the reviews there. You won't see one bad one. No real user of a stylus cares about an eraser function on the back of a stylus, because it's more trouble reversing the stylus, twice, than tapping the eraser function in the software, where you will also likely want to modify it for the erasing you're doing at that time.

    You also don't know anything about how you charge the Pencil. Apple includes an adapter that can plug into any Lightning cable to charge the device from any standard charger with a USB input. The ability to plug the Pencil into the iPad Pro for 15 seconds for 30 minutes is a convienience for when you're somewhere where there is no place to plug a recharger into. It's been praised as an ingenious solution.

    Getting photos into the device isn't difficult, and can be done in a number of ways.

    Admit it, you're just another person who dislikes Apple for some personally obnoxious reason.
  • dsumanik - Friday, January 1, 2016 - link

    Dude I don't hate Apple, I own a 6s iPad 2 Mac mini, MacBook Air and 2 Thunderbolt displays. My rant is directly targeted at At's failure to do basic testing anymore and just read the script the sponsor sends them... I went on about Apple because buddy brought it up, and yeah I tried editing on the new iPad, brought some test images from d7200 to the local Mac store...fundamentally there's is no diff from iPad 2. Same software, larger screen, slightly faster. Like I said I can do 50 photos in Lightroom, catalogued, sorted and retouched and most importantly backed up... in the same amount of time to do maybe 5 on an iPad pro.

    Now let's talk exporting.... Could you imagine exporting say 200+ photos in various sizes/formats on an iPad? This as an extremely common thing for a photographer / web developer to do

    it would take 8-12hrs on an iOS device. Lightroom, one click, walk away, and 5 minutes later done.

    Point is Apple missed the target audience, it's supposed to be for professionals but it slows you down and doesn't offer any advantages except portability. And the pencil charging???? Jobs would have fired cook on the spot face palm central..same as the new battery case lol
  • NetMage - Saturday, January 2, 2016 - link

    Now do the same thing with your PC in the middle of a forest, or in your living room. A bit slower to drive hours to do those 50 images?

    Just because it isn't for you, doesn't mean it isn't much better for others. Same with the battery case.
  • dsumanik - Sunday, January 3, 2016 - link

    Did some digging netmage is a paid-for commenter hired by Apple PR.

    Honestly.... defending the apple battery case bud? At least TRY not to be obvious.

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