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Realtime throughput 802.11ac

rahul nair
Beginner
Beginner

Hi all ,

I have been doing some testing with a 802.11ac (Wave 1) AP - recently configured and installed at my workplace .

Now theoretically i understand that Wave 1 is supposed to give me 1.3 Gbps aggregated throughput .

What would a realistic figure ? 

Below is my iperf throughput summary,  and to my surprise the throughput being recorded it "too" low for 802.11ac standards .

[ 5] 0.00-22.02 sec 86.2 MBytes 32.8 Mbits/sec receiver. 

I have an 80 MHz channel bonding configured . My laptop adapter is also .11ac compliant, with a 2x2 mimo capability /

I have no idea what is restricting the overall throughput .  Am i missing something here ?

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Accepted Solutions

Leo Laohoo
VIP Community Legend VIP Community Legend
VIP Community Legend

Will .11n clients connecting to the same BSS affect the .11ac throughput ?  

( Similar to .11b/g and .11n coexistence issue ? )

Co-exist?  They can.  

Download with real 802.11ac wave 1, wave 2 speed?  Not with 2 x 2 MIMO they won't.  

Let me spell this out, 802.11ac wave 1 & wave 2 is going to be difficult for everyone.  Wireless clients don't have the necessary grunt to do data transfer past 900 Mbps because there is not enough CPU and battery life to do it. 

802.11ac wave 2 is a very, very, very EXPENSIVE network.  The APs will need to be able to have multiple gigabitEthernet ports PLUS the network must be able to handle >10 Gbps traffic.  

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13 Replies 13

Leo Laohoo
VIP Community Legend VIP Community Legend
VIP Community Legend

My laptop adapter is also .11ac compliant, with a 2x2 mimo capability

2x2 MIMO only?  

Let's say you're on the surface of the moon and you are the only person there.  With 80 Mhz channel-bond and 802.11ac, wave 1 enabled then the speed achievable with an 802.11ac wave 1 FULLY complaint wireless card is about 900 Mbps. 

Hi Leo ,

Thanks for your reply :)

The sad part though is -  this means in my environment the throughput offered by an 802.11n client/AP and 802.11ac Client/AP  is the same ! 

Will .11n clients connecting to the same BSS affect the .11ac throughput ?  

( Similar to .11b/g and .11n coexistence issue ? )

Leo Laohoo
VIP Community Legend VIP Community Legend
VIP Community Legend

Will .11n clients connecting to the same BSS affect the .11ac throughput ?  

( Similar to .11b/g and .11n coexistence issue ? )

Co-exist?  They can.  

Download with real 802.11ac wave 1, wave 2 speed?  Not with 2 x 2 MIMO they won't.  

Let me spell this out, 802.11ac wave 1 & wave 2 is going to be difficult for everyone.  Wireless clients don't have the necessary grunt to do data transfer past 900 Mbps because there is not enough CPU and battery life to do it. 

802.11ac wave 2 is a very, very, very EXPENSIVE network.  The APs will need to be able to have multiple gigabitEthernet ports PLUS the network must be able to handle >10 Gbps traffic.  

Thanks Leo . 

This was really an eye-opener . 

I always have a tough time with our users/stakeholders expecting Gigabit throughput from .11ac network.

Hence thought of clearing this up with you and others here :)

Thanks ,

Rahul.

We're seeing low throughput for our AC clients, the same speeds as our 802.11n clients. Haven't been able to figure it out. We get about 250-300Mb tops when we should be seeing twice that.

Leo Laohoo
VIP Community Legend VIP Community Legend
VIP Community Legend

We're seeing low throughput for our AC clients

Hi Ben, 

1.  What is the exact make and model of the wireless NIC? 

2.  What is the exact driver versions are these wireless NIC running on?

We're using Intel 7265 and 8250 clients. Running driver version 19.20, 19.40.

Thanks

Ben

I was getting around 48 MB/s last time I checked on an Intel 8265-AC with Intel 19.40 drivers and an Cisco 2802i running an 80 MHz channel. A few other clients were connected (but mostly mobile phones in standby) and the test was done in a building with a lot of wireless APs and clients. So I'm quite happy with the trough put of the 867 Mbit/s connection speed shown in Windows 10.

The 50% loss of the brutto transfer rate still seems to apply ;)

Run and iperf test between wireless and wired and then wireless to wireless.  That's  how I test actual throughput to see if things are working fine.  What you see in the Windows wireless tray for speed, divide that in half and that would be the theoretical max throughput you can see. If there is a lot of other wireless RF noise from adjacent neighbors, well it would then be hard to achieve that theoretical max throughput.

We see varied throughput in our sites depending where the site is, the NIC used to test and the radio band the laptop associated on.

-Scott 

*** Please rate helpful posts *** 

-Scott
*** Please rate helpful posts ***

Leo Laohoo
VIP Community Legend VIP Community Legend
VIP Community Legend

We get about 250-300Mb tops when we should be seeing twice that.

Do a run of the LAN infrastructure first.  Check and make sure there are no line errors, like speed and/or duplex mismatch, on the ports.

If we change the AP from local to flexconnect the speed doubles. See below screenshots, I'm not sure where the issue lies, wlc config, qos somewhere? It's the only change, there's no traffic today, no students/staff.

local

flexconnect

Not sure if it's QoS, but the WLC can mark your traffic with the "silver" QoS in default SSID settings, if enabled.

If you use local mode, the whole wifi traffic is sent from the AP to the WLC. From the WLC it will get into the LAN into the configured configured VLAN. So the same traffic flows twice over the interface to the WLC. There could be the culprit.

It's possible that the channel assignment isn't anymore the same after changing the AP mode, which could also cause a different performance.

Regardless of this, the client drivers play a huge role (Intel just released updated drivers with several bug fixes for the 1800, 2800, 3800 AP series with the 19.40 package) and Cisco released the new 8.2.151.0 WLC code which also fixes a lot of issues with the x800 AP series.

emily00001
Beginner
Beginner

As Leo stated it's pretty difficult to max out wave 1 and wave 2 ac but on a sidenote the AP3800 has a multigigabit port although in most deployments the main limitation, at least if you want to max out wave 2 is that there are only two 160 MHz channels.

What TX rate does your client report? What's the channel utilization on the AP?

I'd say your result of32.8 Mbits/sec is far below what you should expect. Under what conditions did you perform the test? Lab, high load environment?

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