When 802.11n clients operate in a mixed environment with 802.11a or 802.11 b/g clients, 802.11n provides a protection mechanism to interoperate with 802.11a or 802.11 b/g clients. This introduces an overhead and reduces the throughput of 802.11n devices. Maximum throughput is achieved in Greenfield mode where only 802.11n clients exist.
Factors such as Channel width, Guard Interval and Reduced IFS (RIFS) play a major role in the bandwidth. Table 1 and Table 2 show how these factors affect the bandwidth.
Clients ability to send a Block Ack instead of individual frame acknowledgements.
MCS Index configured on the WLC.
Proximity to AP—Clients closer to the AP experience higher data rates. As clients move farther away from the AP, signal strength reduces. As a result, data rate decreases steadily.
RF environment—Amount of noise and interference in the environment. The less the noise and interference, the greater the bandwidth.
Encryption/ Decryption—Encryption in general reduces the throughput due to the overhead involved in the data encryption/decryption process. However, advanced encryption standards, such as AES, can provide better throughput when compared to other encryption standards, such as TKIP and WEP.
Wired Network Infrastructure—Bandwidth of the wired infrastructure determines the speed of the traffic to and from the wired network to the wireless clients.
If using an AP1250, change the AP to H-REAP mode for a 5-10% boost.
If using an AP1140, keep the AP in local mode and enable TCP MSS on the controller. Use the config ap tcp-adjust-mss enable all 1363 command in order to enable it.
Disable RRM scanning to prevent any throughput drops when going off channel. This can yield a 1-3% improvement.
Disable RLDP to ensure the AP does not attempt to connect to rogue devices during testing.
Use a Wireless Controller 5508 as the data plane is superior to the 4404-series.
Here is a quick simple answer.... Make sure your encryption is set to WPA2/AES and also make sure WMM is enabled and 40 MHz channel width is being used. The last two along with AES is what is required to see 300mbps from a compatible 802.12n device. Make sure when you test also, that your near the AP so that signal isn't an issue.
Look at the link posted in the other post also. Both post has very good info.
Transferring Crash file from standby: Login to the Active WLC in HA.
From CLI: (Cisco Controller) >transfer upload datatype crash (Cisco
Controller) >transfer upload filename (Cisco
Controller) >transfer upload mode tftp (Cisco Controller) >transfer
This is the start of a display filter cross reference between Wireshark
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