Data Packets could not received due to low RSSI on 9130AXE and 9130AXI

[brian zhang1]

WLC 3504:8.10.151.0

AP C9130AXE-H, External antenna for AXE(enable port A+B): AIR-CAB002-D8-R=  + 2*AIR-ANT2524DW-R 

And AP C9130AXI-H(Enable All ports)

From the client side, RSSI is very strong(-20dBm), but the data packets send from Cisco AP is very low：

AXI：data packet -48dBm, Beacon -19dBm

AXE:data packet -63dBm,Beacon -25dBm

The result is, from the client, RSSI is very strong, but when moving client away from AP, even RSSI is still very strong from the display, because the TX power of data packets is so poor, client is not able to receive data packets. this can be easily obervered as well in air sniffer. and client roaming is not able to trigger due to RSSI is still strong(from Beacon)

The measurement was done by close the client with antenna and air sniffer.

How can we increase the TX power for data packets?(disable 11ax to use 11a see same issue)

This is a serious issue to deploy this serial APs to warehouse etc.

[Scott Fella]

Did you mean to state you have AP C9130AXI-E not an AP C9130AXI-H?  Signal is affected by mounting height also and choosing the right antenna to provide the correct down tilt to clients below.  You need to understand the rf propagation for the antenna you choose and this is done by using a tool like Ekahau or AirMagnet.  You will be able to tell where you signal is strong and weak, it doesn't mean that if your AP or antenna is 30 feet high that the signal below should be the same between the two different models of access point.  If the TX power is not what you want, you can always increase it as long as it is not already at max TX power.  You can find how to do this in the guide for the code you are using.

[brian zhang1]

Hi Scott, you did not understand my question, I have several 9130AXI-H and 9130AXE-H APs. I is internal antenna model and E is the external antenna model. when I did the test, sniffer, station and AP are zero meters. the issue here is station show rssi is great because it  will measure the RSSI through beacons sent from AP typical 100ms, but the real data packet like ICMP packets sent from AP is very low(-30dB to -40dB comparing beacon), which make the device think RSSI is quite good(The RSSI of beacon) and not trigger roaming when it move away from APs, but actually station already not able to receive any data packets, that is what I obeserved during deployment that's the reason I capture the sniffer. if you download the PNGs(not sure why it can not previewed) I attached and you will see what I was saying. Such performance of APs is totally no use for any user.

I am surprised that Cisco sells such quality APs to the market, note I have 3702s, 3802s, and also lots of old models, none of them see same issue before.

[Scott Fella]

The reason I asked is because if you look at the ap model you stated in your original post, you have AP C9130AXI-H and you have AP C9130AXI-I, both are I's.  I think you are testing too close to the AP, you should be testing further out.  I don't know how your configuration is also, so can't suggest anything there, but I have 9120's and 9130's and no issues at all.  I don't have an E's to test with.  My suggestion is to open a TAC case and let them take a look, that is your best bet.  You didn't mention how your ap's are setup, controller or EWC and or what code, so they can help you with that.

[brian zhang1]

Yes, I see the typo, corrected, thanks.

too close should not a issue, move to 1 meter or 2 meters, it's the same. significate different for the RSSI, WLC is 3504, version was also there(1st line), I already put into post. I suspect it may be only issue on H domain, as I have friend in US which is B domain, similar setup but his works well.

I was trying to see if anyone in the community see similar issue, otherwise yes, I need open TAC case.

[Scott Fella]

It could be the model like you said, but I too have only the B domain since I'm in the states.  Maybe I will give it a shot later this weekend since I have a few 9130's in a box, but B domain and will be connecting to a 9800-L.

[brian zhang1]

3504 is still ok actually, it is confirmed by Cisco.
BTW, I tried virtual wireless controller, same issue.

[Scott Fella]

3504 is fine... if you really want to test those ap's you should look at converting them to EWC or standup a 9800-CL.  This way you have additional data and can determine if there is a difference or not.

[brian zhang1]

It’s not related to WLC, as I said, I already tried physical controller and virtual controller with different IOS version, no difference, I could not accept EWC or 9800.
BTW, with same iOS version for 9800 or 3500, the downloaded firmware to AP is the same, such detailed TX power should be determined by AP only, Controller can only provide level like for 5G level 1 to 8. 1 is the highest. but for the packet power level of different MCS index, AP will load it and deside the final Tx power.

But there could not so big different TX power for different MCS or packet

[Scott Fella]

There always can be a difference with controller models and images, so don't compare it like its the same.  You can have a bug dependent on ap model but affects certain code and vice versa.  Everyone has seen this in the past and keep in mind the controller provides the image to the ap.  If you move an ap from a 3504 to a 9800, the ap will download and install the image, which means it is not the same, or else there would be no download and reboot. 

It's up to you how you want to test, but at least test with a few of the external ap's with various antennas if possible.  TX power is controller by the controller, the overall TX is decided by power, gain and loss.  If you have a bad antenna for example, is it the ap's fault or controller fault?  The controller tells the AP what power it should have and the AP sends that out on the antenna even if you have a booster or attenuator, the AP will not adjust for that.

Open up a TAC case since you should have support as the AP's are pretty new still.  Let them provide guidance on what you are seeing.

[Rich R]

Agreed TAC case is your only option at this point.

[patoberli]

I'm not sure if you are actually seeing TPC being in use here. I think for 802.11ac and ax clients this is mandatory. So the AP and client adjust on the fly the transmit power to reach the needed strength for a fast transmission, while only using as much power as is needed. The beacons on the other hand will be sent at full power configured for the radio. 

There are by now several variants, one of them Cisco proprietary (using CCX extensions): 

https://www.cisco.com/c/en/us/support/docs/wireless-mobility/80211/200069-Overview-on-802-11h-Transmit-Power-Cont.html

[brian zhang1]

No, 3702, 3802 works well with TPC disabled. TPC only decide the max TX power, I am working with TAC case, Cisco is still investigating

[ameliascotts80938]

The Cisco Catalyst 9130 Series Access Points, paired with the Cisco Digital Network Architecture (Cisco DNA), are enterprise-class products that will address both your current and future needs. They are the first step in updating your network to take better advantage of all of the features and benefits that Wi-Fi 6 provides.

https://www.cisco.com/c/en/us/support/docs/wireless-mobility/80211/200069-Overview-on-802-11h-Transmit-Power-Cont.html

[brian zhang1 · Accepted solution]

Get the TAC support that this is indeed a firmware issue in AP, have a temp firmware for test which does fix the issue, waitting the final AP release combined into WLC OS.