New iMacs With P55 Chipset (i5/i7) DO NOT Support Jumbo Frames

Discussion in 'iMac' started by tsugaru, Dec 2, 2009.

  1. tsugaru macrumors 6502

    Joined:
    Feb 9, 2003
    Location:
    Edmonton
    #1
    Way to be Apple. Way to be. Skimping a few cents on an Ethernet controller for your higher end prosumer computers. The other iMacs released this cycle have NIC controllers with jumbo frames. Heck, even my original 20" 2.0GHz Intel iMac had jumbo frames, as did the gimped 24" iMac 2.66GHz 9400m I sold a few weeks ago.

    Seems like with every iMac there's always a slight niggle that prevents it from being a perfect machine.

    Aside from all the issues with mine (which will be rectified soon) and others, I'm forced to quote Nancy Kerrigan with a resolute "Why?"
     
  2. edesignuk Moderator emeritus

    edesignuk

    Joined:
    Mar 25, 2002
    Location:
    London, England
    #2
    I'm sure it matters to you, but really, this is the most consumer targeted computer Apple make. How many of them do you think know what a "jumbo frame" is and why would they care? I didn't know what it was, and I'm not a complete idiot with computers.
     
  3. Bluegiz90 macrumors member

    Joined:
    Oct 29, 2009
    #3
    Whats Jumbo Frame? :confused:
     
  4. KentuckyApple macrumors regular

    KentuckyApple

    Joined:
    Jul 2, 2003
    Location:
    Chicago, IL
    #4
    Just curious, but what kind of data are you working with that you need to use jumbo frames?
     
  5. AdeFowler macrumors 68020

    AdeFowler

    Joined:
    Aug 27, 2004
    Location:
    England
    #5
    Something to do with Nelly the elephant I think ;)
     
  6. Husker macrumors newbie

    Joined:
    Mar 9, 2009
    #6
    not only do I not have the slightest idea what this thread is about...but quoting Nancy Kerrigan? Seriously?
     
  7. tsugaru thread starter macrumors 6502

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    Feb 9, 2003
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    Edmonton
    #7
  8. KentuckyApple macrumors regular

    KentuckyApple

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    Jul 2, 2003
    Location:
    Chicago, IL
    #8
    What happens when you increase the MTU? What size are you trying to use?
     
  9. tsugaru thread starter macrumors 6502

    Joined:
    Feb 9, 2003
    Location:
    Edmonton
    #9
    I use 9000, as all my other stuff supports it.
    On the i7, You can't increase it, whether it's through the network pref pane, or via sudo ifconfig en0 mtu x.

    It's due to the NIC/PHY. The ones on the LGA775 based iMacs (Core 2s) use a PHY that allows for jumbo frames. The LGA1156 based iMacs (Core i5/i7) do not.

    There is a discussion of this on the Apple forums.

    http://discussions.apple.com/thread.jspa?threadID=2236017&tstart=0
     
  10. knewsom macrumors 6502a

    Joined:
    Jun 9, 2005
    #10
    I wonder if this is something that will be fixed with a firmware update. That's a pretty major problem.

    Now I'm glad I bought a DROBO instead of a fast NAS.
     
  11. tsugaru thread starter macrumors 6502

    Joined:
    Feb 9, 2003
    Location:
    Edmonton
    #11
    Firmware will not fix it.
    It's a hardware issue.
    http://www.broadcom.com/collateral/pg/5764M-PG100-R.pdf
    See page 4.

    To relate it for those who are like 'why is this a big deal?'
    When you're transferring files consistently and have over 3TB of network storage with about 2TB full, the difference between 20MB/s and 40MB/s adds up quite quickly.
    To put it on another level; if you bought a new car, and ponied up for air conditioning, would you want your power doors/locks taken away just because you upgraded?
     
  12. edesignuk Moderator emeritus

    edesignuk

    Joined:
    Mar 25, 2002
    Location:
    London, England
    #12
    Fair enough. Most people won't know what "jumbo frames" are, but from what you say many will see the implications on them cheeping out with this. Apple bastids. :rolleyes:
     
  13. tsugaru thread starter macrumors 6502

    Joined:
    Feb 9, 2003
    Location:
    Edmonton
    #13
    Agreed.

    There are a bunch of people just looking for the basics (fast CPU/RAM, shiny screen, et al) but I know there's a bunch of us who like a little more. To be downgraded for going high end is kinda odd.
     
  14. Tom Sawyer macrumors 6502a

    Tom Sawyer

    Joined:
    Aug 29, 2007
    #14
    I can confirm that the new 2010 models have the same limitation... no MTU higher than 1500. Very disappointing. :mad:
     

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