Older 802.11 protocols used instead of newer N/AC

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  • Updated 3 years ago
Endpoints which are capable of N and AC often choose to connect to AP's G protocol.   Can someone help explain why both AP and endpoints support N/AC but connect with older G/A protocols?
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Marc Bishop

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Posted 3 years ago

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Matthew Gast

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The AP that a client connects to and the data rate that it chooses are both determined by the client device, so the answer is specific to the particular client device.  In general, most client devices are driven by the signal-to-noise ratio (SNR).  Higher SNRs correspond to higher data rates.  The OFDM PHYs (11a/11g) require lower signal-to-noise ratios than the MIMO PHYs (11n/11ac).  If a connection is of marginal quality, where SNR is close to the lower limit for a data rate, the client device may choose to back down to a lower rate that that has a higher margin.  Sometimes, this results in choosing an OFDM data rate instead of a MIMO one.

Is there a particular endpoint that you're interested in getting the answer for?
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Marc Bishop

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ya, our new Dell Latitude e5540 has a low RSSI of -29dbm and a signal to noise ratio of 59 db but continues to use 802.11ng Radio Mode.   This is an excellent example of among our 5 AP's that support AC endpoints connect to older protocols
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Andrew Garcia, Official Rep

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A client's connection will be forced to 11g (or 11a) speeds if WEP or TKIP is used for encryption, or if WMM is disabled on the SSID.
(Edited)
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Marc Bishop

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In all connections of our 22 Aerohive AP's all encryption being used is AES.  WMM is enabled.  Thanks for your help.
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David Coleman, Employee

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Also verify that any radio profiles you might have configured are in the correct mode.  2.4GHz should be in "g/n" mode and the 5 GHz profiles should be in "a/n/ac" mode