How do you use Full-Duplex mode with Dual NIC's

Discussion in 'Networking' started by StraightPipe, Sep 21, 2006.

  1. StraightPipe

    StraightPipe Golden Member

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    I'm about to buy a new Giga-Router and started noticing alot of them support full duplex of 2000mbps. I'm also thinking that my new server box has 2 gigabit ports on the back of it.

    How do you go about setting it up? Has anyone tried it?
     
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  3. JackMDS

    JackMDS Super Moderator<BR>Elite Member
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    Setting Up what?

    :sun:
     
  4. nweaver

    nweaver Diamond Member

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    "Teaming" or setting up dual NIC'S requires enterprise level hardware (NIC's and switch). Full Duplex shouldn't be an issue though, and will most likely work without you doing anything.
     
  5. StraightPipe

    StraightPipe Golden Member

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    The switch I have supports up to 2000mbps (Full-Duplex Mode).

    As I understand it, that means use two cables, one line up and one line down. Really it's not going to go that fast but the idea is one-way traffic has less collisions.

    I'm not 100% sure that my Dual Gigabit LAN supports 2000mbps though. It's onboard my ASUS P5B - Deluxe WiFi Edition motherboard.

    Edit: it looks like my NICs are the problem. They're all 10/100/1000. I figured 2 x1000 is 2000, right? Wrong :)

    I'll just have to settle for 1000mbps. I've only moved a couple of gigs across it so far, and it looks like the average is about 20MB/s. Not very impressive considering the theoretical max is 125MB/s.

    What are your typical Data transfer rates on Gigabit?
     
  6. jmcoreymv

    jmcoreymv Diamond Member

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    Full-duplex means you can go 1 gb/s in each direction simultaneously for a total of 2 gb/s both ways. You only need one cable.
     
  7. Madwand1

    Madwand1 Diamond Member

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    This "full duplex" "2000 Mb/s" is just marketing confusion. Every modern gigabit NIC and switch will do this, and it's no big deal. Some manufacturers harping on bidirectional througput instead of one way throughput makes it confusing for those new to this. Newegg for example took it further with some switches being classified as 100/200/1000/2000 etc., as if they're different from switches advertised as 100/1000. But they're not, so it's just marketing confusion...

    Teaming multiple NICs is an advanced topic, and to cut to the chase, will typically do nothing for the home user in terms of single file transfer performance, even if he/she gets it set up properly with teaming software/drivers, a smart switch, a couple of computers with multiple NICs, fast storage arrays, etc. It can do something for multiple simultaneous transfers as seen on multi-user servers, but this situation is rare at home.

    Here's more on that: http://www.alacritech.com/html/teaming.html

    Moreover, with 20 MB/s file transfer performance, you've already shown that your file transfer is not (at all likely to be) limited by network performance. So teaming / "2000 Mb/s" etc. would be pointless.

    20 MB/s is not far from typical GbE performance for average / slow drives. The number I throw around is 30 MB/s, but this varies; some might get 20-25, some might get 40-45, etc., this depends mostly on the HDs involved, on both ends of the transfer, but of course depends on the entire chain, including the file system, state of the files on the drives (crowding, fragmentation), whether the HD controller and NIC are on a shared PCI bus, etc.

    You can use tools like iperf to see what your network speed is in isolation of drive speed. These typically give figures much higher than file transfer speed, showing that the "problem" is not network per se.

    E.g.

    server: iperf -s
    client: iperf -c server -l 60000 -t 21 -i 3 -r