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Saturday, 1 January 2011

Beware the Fritz!Box 7390's 'green' LAN mode

I've just been testing a D-Link smart switch, and due to limited space on my desk had to stick this in front of my cheapo Belkin 8-port Gigabit switch (F5D5141-8v3). This meant the link status LEDs were hidden from view. Having finished the review and packed up the D-Link, I noticed that the uplink to the Fritz!Box 7390 (which I have on long-term loan) was only running at 100Mbps. Puzzled, I tried connecting the PC direct to the Fritz!Box, with the same result - all the LAN ports were running at this lower speed.

Thinking it might be the new firmware upgrade, I tried to think of something that might have changed. For some reason I thought of the 'green' LAN feature, so I checked it and noted that the ports were set to automatic 'green' mode. I changed this to 'always on' and hey presto, the link speed changed to 1Gbps. I wasn't sure why, though, but checking the help file revealed all - the 'green' mode just reduces the port's speed to 100Mbps when a device is connected. Obviously, this does help the Fritz!Box save power, but for some reason I thought that it did other clever things like reducing signal strength for short cables, like some other networking kit I've seen (D-Link's Green Ethernet technology is an example). It does turn off power to unused ports, however.

So be careful activating the green function if you need full-speed LAN connections - one of the few annoying things about the Fritz!Box is the lack of visible port status information - and even in the web interface there's no indication of the active link speeds. The safest compromise between speed and power consumption is to set all ports to the 'Identify Automatically (Power Mode)' setting - this runs ports at the full 1Gbps, but turns them off when there's no cable connected.

Don't do this if you want a full-speed LAN

UPDATE 31/1/2011: I've corrected parts of this article, as the Fritz!Box 7390 does turn off power to LAN ports with no device connected, unless the 'Always Enabled' setting is used.

UPATE 19/9/2012: The latest FritzOS 5 firmware adds the details of port speeds to the energy settings screen shown above.

17 comments:

  1. THANK YOU THANK YOU THANK YOU!!! Although mine were in the mode suggested already, and I had to switch them to "automatically identify (power mode)" to get gigabit ethernet happening here. I wish I'd known this last night when it was driving me crazy!

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  2. +1 million

    Many thanks!

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  3. Oh man, I cannot believe I missed that. I was completely on the wrong foot by the 1Gbit connection on port A. As my server was in that port I never disconnected it and only used the other ports for my other computers.
    I was convinced the problem was in the linux forcedeth driver, but then another (windows computer) wouldn't connect at 1Gb either. Both used the same Realtek chip so then I thought there was a problem with that. Caused me sooo much frustration.....
    THANK YOU THANK YOU THANK YOU !!!

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  4. thank you - half way there

    I have a Home Theatre PC (HTPC) connected via a TP-Link SG1016 Gigabit switch to the Fritz.box.

    There is a gigabit link to the switch box from the HTPC, but when checking the speed on the fritxbox and the HTPC it says only 100Mbits connection - so I'm guessing the connection between fritzbox and SG1016 is only 100Mbits.

    Any ideas why this might be?

    cheers
    Fat Craig
    Brisbane, Australia

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  5. @ Craig Hi there, and thanks for dropping by. Which device is saying that the link is 100Mbps, that is, how do you know? If it is shown on the HTPC it might be that the network adapter isn't auto-negotiating the link speed correctly (but then the switch would tell you that). Also, which Fritzbox model?

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  6. THANK YOU THANK YOU THANK YOU!!!
    2 days I m looking for this problem !

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  7. Thanks a lot! Solved my problem immediately!

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  8. I don't have the Settings option on the energy monitor panel

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    Replies
    1. Same here, just got the lattest Firmware too 06.06

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    2. Same here. No option button...

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  9. Thanks man was about top return the box

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  10. Users may be interested to know that the location for these settings has changed in a more recent firmware update.
    The 'Green Mode' settings can be found in;

    Home Network > Network > Network Settings tab

    Don't forget to hit 'Apply'!

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    Replies
    1. Thanks for that! I'd spotted that, but didn't think to update this :-)

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  11. Many thanks to all. I have the 7360 and I can only have 2 power and 2 green, still better than the 1 power I have been struggling with. I will try the ISP for an upgraded router. Again thanks

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  12. If you hit Apply does the FritzBox reboot? I'm backing up a large file and it has 16 hours to go. :-(

    If I hit Apply will the port speed automagically increase or will that interrupt my backup?

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  13. You wrote: "the 'green' mode just reduces the port's speed to 100Mbps when a device is connected. Obviously, this does help the Fritz!Box save power".

    >>> I don't understand how port speed can save power?

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    Replies
    1. Gigabit Ethernet needs more processing power than 100Mbps Ethernet, which in turn uses more electrical power - obviously not a lot, but it does. That's why they call the slower mode 'Green Mode'.

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