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ryanfd

A couple of Wireless questions

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Hi people!

 

I had a couple of questions. I'm studying at the moment for my CCNP wireless. I don't have too much practical experience with site surveys. I've watched Cisco live videos, read the CWNA book and several Cisco books... as well as design guides. but I think there are a lot of things which can only be known through experience... or at least I can find any info on them.. so maybe someone round here can help with these questions:

 

1) For a post deployment survey containing voice, data, video and location. Should the post validation be a multi-survey for each of these technologies... or would doing a post validation for just voice for example be enough as this covers the requirements for the other technologies (such as cell edge... although i suppose it doesn't account for triangulation for location).

 

2) Maximum hops for a CLIENT in mesh networks. I know outdoor mesh backhaul hops and recommended indoor hops for mesh networks... but cant find any info on specific requirements for Clients in the mesh network with regards to maximum/recommended hops..

 

Thanks in advance for any help!

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#1

 

In a perfect world, you would test for each on independently. The reality is that voice is so demanding on your network, and the cell edge so specific (-67dBm w/ 25dB SNR) that if your cell can handle voice, it can handle data without an issue, as data will pass even at -75dBm cell edge with garbage SNR.

 

You're going to have to test at least twice, once for voice, once for location. Location is all about being able to hear at least 3 APs at -72dBm, but in a perfect world being able to get inside a quadrant of 4 at -75 dBm. That's so much different than voice. However, if your network can do location, it can do data. Make sense?

 

 

 

#2

Then you aren't reading the right books. It's spelled out crystal clear in IUWMS. Maximum hops is 1200 feet (give or take) and 4 hops. Each hop halves the throughput. And even in a best case scenario of a wave 1 outdoor AP with all 3 ss streams hitting and a full 30 dB SNR between two mesh APs, your backhaul is 450 Mbps. That's like "perfect" lab specs. Half that each hop.

 

The reality is that even current guides are hoping for a best case of 54 Mbps from MAP to rap, and then maybe that rap to rap. You do the math. Your functional throughput is 5.5 Mbps second with four hops.

 

Never go over four. If you have to, then find a way to get more RAPs or deploy a ptp / ptm wireless bridge to give you "wired" access. Then hang a switch off your wired remote wireless bridge, add a CUWN AP and have it serve clients.

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