Forum

Anyone have a reasonable way of explaining to a client how the Hidden Node actually works?  I have tried and do not seem to be able to get him to understand.  I have a client that cannot conceive how this works.  He will not understand how if two clients, say two iPads that are connected to the same AP but cannot receive a signal from each other can cause a issue.  I set up a test and performed some sniffing of the traffic on a AP and I am working to filter on the two clients to show the data.  In the mean time any additional ideas would be appreaciated.

If you're trying to convince the client that the hidden node problem actually exists, it's documented in many 802.11 books, like the CWNP study guides and "802.11 Wireless Networks: The Definitive Guide" from O'Reilly.  I would suggest reviewing of these materials with the client, as they explain it pretty clearly.  If the client just doesn't get it, well, they hired you because you do get it :-)

--
@@ron

I'm feeling rather spunky today here is a link for ya ;)
http://bit.ly/RLLnMG

Thanks Sbyrum, while Google has many answers, I guess I should have specifically asked for real-world experiences since that is what I need.  I did not expect to be told to “Let Me Google That for You” and accept what Google decides I should look at for answers. I have read many references but obviously I need more information because this client still does not believe my answers.

I should probably expect the client to not believe facts, seeing as how he has residential APs deployed in a commercial or hospitality environment. And he expects it to work with 100% reliability.  My next steps are to perform some additional testing and sniffing to prove my point on-site.

 

It's difficult to demonstrate a hidden node problem because it can be intermittent and subtle.  The access point may mitigate the issue by using CTS-to-self when error rates are above a certain threshold.  The stations also might be using RTS-CTS, which mitigates hidden node problems.
Even without these measures, the stations will be able to communicate, but error rate will increase and performance will decrease.  If things don't explode in a dramatic fashion when there's a problem, it's sometimes difficult to prove that the problem exists.

It sounds to me like your client either needs a better understanding of the theoretical problem or needs to trust more in your judgement as a wireless professional.
--@@ron