Troubleshooting Approach

Troubleshooting wireless–

1A: Look at the RF spectrum(layer 1) via any given spectrum analyzer software (in previous blogs i have compared some free and cheep versus more expensive ones)

1B: Take a look at how the spectrum looks like under each Access Point to give its view of the frequency

1C: Take a look at how the spectrum looks like where the general user-base is located + ‘areas of concern’

Stop & Ask :
After determining what each AP’s perspective of the spectrum looks like
– can I quickly gauge why the environment could be experiencing a poor wireless experience?
– any CCI?
– any non-802.11 RF?
– how does CU look like under each AP compared to where the ‘areas of concern’ are
– anything incorrect with the placement of the APs?

2A: Use Airtools (@adriangranados) or Omnipeek(when I want to see more than 1 channel) to look at what the Layer 2

2B: Again capture traffic under each(few) Access Points (I take 2-5 minute captures) + ‘areas of concern’

Stop & Ask:
Open up over-the-air captures and analyze.
– can I quickly gauge why the environment could be experiencing a poor wireless experience?
– how does retransmissions look like under each AP?
—- yes yes.. you’ll always have some % of retry
– what does % of packets that can be seen by your capture laptop show corrupted frames/CRC versus good(FCS checked out) versus total number of packets/frames captured during the period

screen-shot-2016-09-10-at-10-02-59-am                                       NETWORK WITH ISSUES

3: Run over-the-air capture through Eye P.A

Stop & Ask:
– how is the 802.11 medium being shared among the clients?
– any one client abusing access?
– what does the data rate percentages
for the clients accessing the network look like?

4A: Software configuration review

Stop & ask myself:
– what are the TxPower settings of the APs (compare analysis with 1A-4?
– too many BSSID(compare to 3A)?
– do the logs on the systems provide any hints
– QoS applied on WLANs?
– debug..debug..debug …sometimes as good as over-the-air captures on what could be possible issues

 

screen-shot-2016-09-10-at-10-03-27-am
NETWORK WITHOUT ISSUES

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