here are some notes and test results for those in need of the same thing. i have also documented some questions at the end. I’m still seeking some answers and not 100% sure I have tapped the potential of these 1062e AP’s running in bridging mode.
Test details:
- HP DL ProLiant-class servers with updated NIC drivers for the test
- Copy from a windows 2003 server to another windows 2003 server
- CIFS file transfer of a set of small files totaling 1.763 gigabytes
- wired NIC speeds = 1gbps connected via cisco 2960 series switch (current switch firmware)
- wired transfer speeds of about 176 Mbps throughput (baseline wired transfer)
Wifi details: So I have a baseline in this environment of about 175 Mbps transfer rate over the Gb Ethernet NIC’s. Now I try to optimize my transfer over the WAP bridged environment. Here are the details:
Two cisco 1602e AP’s configured in bridging mode (carrying 3 vlans) (Fairly recent 15.x OS).
Cisco IOS Software, C1600 Software (AP1G2-K9W7-M), Version 15.2(4)JB5, RELEASE SOFTWARE (fc1) System image file is "flash:/ap1g2-k9w7-mx.152-4.JB5/ap1g2-k9w7-mx.152-4.JB5
Using the cisco certified 3-pole patch antenna (AIR-ANT5160NP-R), pretty much line of site @ 35-40m apart. Disabled the 2.4Ghz antenna permanently. Using just 5.0 Ghz.
Native vlan1 carries most of the vlan traffic. The other two vlans were shut during testing or not utilized much at all.
Tweaked several variables on the AP configuration in attempt to optimize transfer speeds.
Both sides of the AP’s were supported by cisco Gb switches.
AP’s uplinked to the switches via 1Gb switchport. Entire path from server to server was 1 Gb, except for the Wifi bridge.
Tried to do testing after hours and verified there was not much other traffic at that time over AP bridge.
Test started out at about 58 Mbps transfer over the air for the above file set.
Variables I tweaked: Things I did to make improvements (and their effect):
Ensure the Dot11radio was configured with WPA & AES authentication:
dot11 ssid BP1-C
vlan 1
authentication open
authentication key-management wpa version 2
interface Dot11Radio1
no ip address
encryption vlan 1 mode ciphers aes-ccm
encryption mode ciphers aes-ccm
Supposedly this is a requirement for 802.11n channel -bonding. I had this above already configured.
Change antenna distance config from 1KM -> 0KM (AP's are actually about 40m apart):
This didn’t yield any substantial performance throughput. Left at 0 though.
2. change Ethernet Encapsulation Transform:RFC1042-> 802.1H
This didn’t yield any substantial performance throughput; reverted back (wanted to keep standardized.
3. Removed the non-vlan-1 vlans (thought there might be some sort of per-vlan-antenna band limitation). Thought I may be losing bandwidth because the AP was dedicating a particular band to a particular vlan in the bridge:
This didn’t yield any substantial performance throughput; reverted back to “trunk configuration”
4. Optimized DFS - was missing one channel in the UNII-2-Ext Spectrum (Band3):
This is pretty important and actually allows the AP to get more chance for success when seeking a 40 Mhz channel. See the below link for the channel breakdown. In the other 5 Ghz bands, there isn’t much room for the 40 Mhz channel allocation. 40 Mhz (double-wide) channel is important for AP, as it allows more information to be sent at one time:
https://sites.google.com/site/802dot11study/ch06/notes
Even though this seemed important, it didn’t really increase my speed too much; I got about 10% bump, but this was probably from choosing a different channel for communication. I was not able to get 40 Mhz channel allocation – see below in conclusions.
5. Change beamfrom from OFDM to RSSI
This didn’t yield any substantial performance throughput. Left the same – OFDM
6. Enable WMM (world mode multi-domain): world-mode dot11d country-code US outdoor
This seemed to provide about 5 Mbps improvement. I thought this was the missing link to achieving remarkable speed gains as it seems to be needed for 802.11n. But it didn’t give me the big jump I was expecting. Nevertheless, I left it enabled. NOTE: there is a bug in the GUI config tool that doesn’t let me configure this so I did it via the command line.
7. Set guard Interval – long or short:
This is a bit odd as you can only configure GI=any or GI=long. There is no hardfixing it at GI=short. GI=short is supposedly best performing, but I couldn’t hardset that. This was default so I just left it at GI=any. I didn’t test speed drop with GI=long enabled, but suspect it would go down 5% at most based on numbers.
8. Enable or disable PSPF (Public Secure Packet Forwarding):
This didn’t yield any substantial performance throughput. Left the enabled – PSFP=yes
Conclusions: so after all this playing around, I only managed to go from about 60 Mpbs -> 70 Mbps in my real world transfer speeds, most of it from probably just setting up on a different channel. My AP shows I’m communicating at high MCS speeds. Use this command to verify. It has a lot of good output:
#AP1 sho controllers dot11Radio 1
My traffic is in these channel allocations: RATE m13-2, RATE m14-2, RATE m15-2, with m15-2 dominating by a factor of 10-20 over the lower rates.
According to this link:
http://www.cisco.com/c/en/us/products/collateral/wireless/aironet-1600-series/data_sheet_c78-715702.html
I should be getting ~137 Mbps (20 Mhz) or 285 Mbps (40 Mhz). If I halve this for the communication being half-duplex and wireless inefficiencies, I should be at about 67 & 142 Mbps respectively. My conclusion is that I’m just not getting the antennas to bond at 40 Mhz. So here I am: a bit stuck and cannot figure out why they are not bonding. I hope this helps others. And I hope someone can point out the missing link! I want to go to about 142 Mbps!
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