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Cisco Meraki Documentation

Channel Bonding

"Legacy" 802.11 clients use 20MHz channels. 802.11n specifies the use of 40MHz wide channels to achieve higher data rates. Channel bonding is supported in 5GHz and commonly uses two contiguous 20MHz channels to create a single 40MHz channel. While channel bonding can provide higher data rates, it will also result in fewer 5GHz channels. 

In some high-density client environments with high wireless saturation, having more available 20MHz channels to spread client usage provides better performance than having fewer 40MHz channels. In addition, not all regulatory domains support using a 40-MHz channel.  

A wide 5GHz channel comprises "primary" and "secondary" channels.  The "primary" channel is used for 802.11n clients that only support 20MHz channel bandwidth (e.g., “legacy: clients). Both primary and secondary channels can be used for clients that support wide channel (40MHz) capabilities. 

The location of the primary channel is specified when you manually configure channel selection in 5GHz. The primary channel is either the upper or lower half of the 40MHz channel. For example, if you are using a 40MHz-wide channel in 5GHz and choose channel 36, then channel 36 (lower half) would be the primary channel, and the secondary channel would be channel 40 (upper half). Conversely, if you specified that channel 40 would be selected as the primary (upper half) and the secondary would be channel 36 (lower half). 

Note: While achieving higher PHY rates in 2.4GHz is theoretically possible, it requires using 40MHz channels (20 + 20 MHz channel bonding) in 2.4GHz, which Cisco Meraki does not enable because this feature is not recommendable in real-world enterprise deployments due to the following reasons: 

  • The 2.4GHz band is 83.5MHz wide and has three non-overlapping channels (1, 6, and 11) in most regulatory domains worldwide. Channel bonding limits the 2.4GHz band to a 40MHz-wide single non-overlapping channel, making over half of the bandwidth unusable. 

  • With Wi-Fi being an unlicensed spectrum that has to be shared, one company or customer should not monopolize the entire spectrum because this is poor spectrum management in the best case and harmful interference in the worst-case scenario.  

  • Even if we consider only one customer or company, using channel bonding in 2.4GHz would limit the entire site to one access point using 2.4GHz, which is not feasible for any enterprise deployment.  

  • Finally, while some major wireless client vendors support channel bonding in 2.4GHz and recommend using 20MHz channel width for reliability and interference avoidance, supporting such a setting on the wireless infrastructure side could cause compatibility and interoperability issues on the client side 

Selectable Channels (5GHz) via Radio Settings in the Meraki Dashboard

Bonded Channel  Channel  Frequency (Mhz)  UNII United States (FCC)  Europe (CE)
36+ 36 5180 UNII-1 Yes Yes
  38 5190 UNII-1 No No
40- 40 5200 UNII-1 Yes Yes
  42 5210 UNII-1 No No
44+ 44 5220 UNII-1 Yes Yes
  46 5230 UNII-1 No No
48- 48 5240 UNII-1 Yes Yes
52+ 52 5260 UNII-2 No* Yes
56- 56 5280 UNII-2 No* Yes
60+ 60 5300 UNII-2 No* Yes
64- 64 5320 UNII-2 No* Yes
100+ 100 5500 UNII-2 No* Yes
104- 104 5520 UNII-2 No* Yes
108+ 108 5540 UNII-2 No* Yes
112- 112 5560 UNII-2 No* Yes
  116 5580 UNII-2 No* No*
  120 5600 UNII-2 No* No*
  124 5620 UNII-2 No* No*
  128 5640 UNII-2 No* No*
  132 5660 UNII-2 No* No*
  136 5680 UNII-2 Yes Yes
  140 5700 UNII-2 Yes Yes
149+ 149 5745 UNII-3 Yes No
153- 153 5765 UNII-3 Yes No
157+ 157 5785 UNII-3 Yes No
161- 161 5805 UNII-3 Yes No
  165 5825 UNII-3 No* No

*Channels are selectable by IEEE 802.11 standards, but unsupported by Meraki 

Please always check with the local regulatory body for channel/power support.

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