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Access network design for branch, remote, outdoor, and campus locations with HPE Aruba Networking access points and mobility controllers.
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802.11n AP connected to a switch that only supports 100 MB

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  • 1.  802.11n AP connected to a switch that only supports 100 MB

    Posted Mar 28, 2012 05:57 PM

    I am troubleshooting a customer network that has deployed AP125s with HP ProCurve switches. The switch ports only support 100 Mb.  In this scenario should HT be turned off to accomodate the 100 Mb switch port?



  • 2.  RE: 802.11n AP connected to a switch that only supports 100 MB

    EMPLOYEE
    Posted Mar 28, 2012 09:20 PM

    No.  It should be just fine.  Make sure the switch is on auto/auto and you adhere to the 3/4/5 rule.



  • 3.  RE: 802.11n AP connected to a switch that only supports 100 MB

    Posted Mar 28, 2012 10:37 PM

    What is the 3/4/5 rule?  And how does it apply to this scenario.

     

    Thanks.



  • 4.  RE: 802.11n AP connected to a switch that only supports 100 MB

    EMPLOYEE
    Posted Mar 29, 2012 06:23 AM

    I apologize.  Just make sure that the ethernet cable is no longer than 100 meters long, so that the AP will power up properly.

     

     



  • 5.  RE: 802.11n AP connected to a switch that only supports 100 MB

    Posted Mar 29, 2012 01:00 PM

    Thanks.



  • 6.  RE: 802.11n AP connected to a switch that only supports 100 MB

    Posted Mar 29, 2012 05:24 PM

    You want to leave HT enabled even if the AP's ethernet port is only at 100 Mbps because we want to operate the link from the wireless client to the controller/network at the highest rate possible. Disabling HT will cause the wireless link to operate at a peak of no more than 30 Mbps (at 54 Mbps PHY rate). Enabling HT on the other hand could potentially tilt the balance the other way so that the wired link could be slower but it isnt half as bad as it sounds.

     

    It is also important to recall that the numbers associated with 802.11 rates are the sum of both directions (uplink + downlink) because the 802.11 links are half-duplex. Your Ethernet link is probably 100/full-duplex. You can easily construct test cases where the numnerical difference will show up, but for much of the time with real users/traffic, it will be harder to detect that the Ethernet link is operating slower than the wireless link.

     

    Your users will be happier with HT enabled than otherwise. 



  • 7.  RE: 802.11n AP connected to a switch that only supports 100 MB

    Posted May 12, 2012 05:43 PM
    Interesting replies to the HT and 100Mbps switch. Users who are hard wired and wireless (Laptops) will run into issues with HT enabled, as Windows metrics will prefer the wireless connection as it reports a connection over 100Mbps. I have a number of sites with only 100Mbps, even down to the controller :( and I'm forced to disable HT due to performance issues, otherwise I need to set the metrics manually on each machine to force it to use Ethernet rather than wireless. At Airheads LV I did raise this issue and was told it was ok to disable HT, otherwise set the metrics under Windows. To tell you the truth, even at 54Mbps on my desktop, I can't tell the difference between wired and wireless, but end users like to complain about it.