Cisco 3850/3504/9120 can't get speeds over 1.2 gbps.

[ChristianSchmidtJosiassen]

Hi

Can't go over 1.2gbps in throughput, i'm testing with two AX Laptops, they are not connected to the same AP, then i try upload a video file to my server, i get 1.2gbps with one Laptop, but when i start to upload a file from the other Laptop, then both laptops goes down to 600mbps.

The 3504 is connected with 5gbit mgig to my 3850.

The two 9120's are connected at 2.5gbit mgig to my 3850, they are also both running at 160mhz.

Why is the throughput being limited to 1.2gbps?

KR Christian Josiassen

[ammahend]

there are many factor that go into effective speed between AP and client, refer to the mcs index, match your spacial stream, channel width etc. and see if your speed match this sheet (theoretically)

https://mcsindex.com

[Rasika Nayanajith]

Hi Christian,

I would say this is normal. Regarding the data rates you see, refer MCS Index

First thing is wireless medium is half duplex and when more than 1 clients in the cell, they have to share the medium. One device will not get 100% time for tx/rx. When single client in the cell, that is the best case scenario where you have no contention.

On another note with 160MHz, it will be OFDM and you can try set 80MHz channel width where both clients can use OFDMA & see if that makes overall benefit when 2 clients in the cell.

HTH
Rasika
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[ChristianSchmidtJosiassen]

Hi

The laptops are not connected to the same AP, so why can’t i get 1.2gbit on both AP’s?

KR Christian Josiassen

[ammahend]

Ideally, you should if both APs are on separate channel and channels are 40Mhz apart just to be overly carefully. In that case both AP should operate independently without interfering with each other. can you confirm channels APs are operating on ? if using channel bonding provide all channel info used in bonding.

[Rasika Nayanajith]

Even though you have 2 APs, since they are in 160MHz I am sure there is CCI (Co-Channel interference). This mean when one client communicate with its AP, other AP & client has to wait until that transmission is over.

Can you pls confirm which channels these 2 APs are operating?

HTH
Rasika
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[ChristianSchmidtJosiassen]

Hi Rasika

Changed to 80mhz

AP1 Channels: 64,60,52,56 

AP2 Channels: 36,40,44,48

But i get the same result.

KR Christian Josiassen

[Leo Laohoo]

I do not understand how anyone could accomplish pushing >1 Gbps on a 1Gbps uplink connection.  

[ChristianSchmidtJosiassen]

Hi Leo

The 3504 is connected at 5gbps mgig.

The 9120’s are connected at 2.5gbps mgig.

As described at the start of this topic.

KR Christian Josiassen

[Leo Laohoo]

And what is the wireless NIC of the laptop?

[ChristianSchmidtJosiassen]

Hi

They are intel ax201’s and they are updated to the newest driver

KR Christian Josiassen

[Leo Laohoo]

If I can get 800 Mbps on an AX laptop and 9130 I am happy. 

I believe you've hit the "limit" to what the laptop can do.  CPU, memory, number of antennas hamper the ability to go higher. 

Please post the complete output to the command "sh wireless client mac <MAC ADDRESS> detail".  (Remove personal identifiable info.)

[JPavonM]

So everytime you check upload speeds from different laptops (I assume they both have same wNIC and driver version), using different APs from same model (same IOS code), and both connected to C3850 via 2.5-Gbps mGig Eth port, WLC is also connected to same c3850 via one 5-Gbps mGig port, you mention that the download throughput from the 1st laptop drops to half when 2nd laptops start uploading the same file. Is it the server is on the same switch? Which Eth speed is the server port? have you tested server performance for simultaneous uploads over wire? Maybe the bottleneck could be on the server side, even the Eth connection or the disk I/O throughput, or the TCP/IP libs.

If the

[ChristianSchmidtJosiassen]

Hi

The server is connected at 10gbps, my workstation is connected at 10gbps, were i can transfer at 400mb/s

KR Christian Josiassen

[JPavonM]

If your wired machine can only transfer up to 400 Mbps then this is not a good indicator. Is there any way you can transfer multiple files from different wired machines at the same time to measure server capabilities?

Again, it seems to me the server is the bottleneck here, but as @Rasika Nayanajith told before, maybe RF coexistence is having something to do, not from your APs which are using different 80-MHz channels, but from neighbours. Remember RF is a shared medium and ALL devices in the vicinity must coexist and allow ongoing transmissions to end before transmitting (I think nowadays it's very difficul not to have ANY device in the neighbourhood that maybe using any channel you use, so impacting performance).

Also remember that if there are ANY device connected to those APs at the same time that are not WiFi6 capable, as all of them should coexist, performance maybe impacted.