Exam 300-425 topic 1 question 25 discussion

I think C & D is correct, 15 % is for High density deployment. Chapter 5 "Applying Wireless Design Requirements" page 355 in CCNP Enterprise Wireless Design ENWLSD 300-425 and Implementation ENWLSI 300-430 Official Cert Guide 2nd Edition

D. Set the cell boundary to –67 dBm This ensures that clients hand off before throughput falls below what’s needed for a reliable voice call. E. Set the cell overlap to ~15% Enough overlap for seamless roaming without excessive co-channel interference. Together, planning for a –67 dBm cell edge with about 15% overlap gives you both coverage and the clean hand-off margins required for VoWLAN.

D and E are correct but C is half correct, we should always consider 5Ghz band, but considering 24 channels in 5Ghz means using UNII-2 and UNII-2e channels and enabling DFS which we can not do that everywhere

D & E is correct. A is incorrect coz this is not in best practice and the same channel is not recommended. B is incorrect coz using 40 MHz will limit the # of channels available. C is also incorrect since 24 non-overlapping channels on 5 GHz will require using UNII-2 and UNII-2e channels w/c require absence of radar. (see pp 3-6) https://www.cisco.com/en/US/docs/solutions/Enterprise/Mobility/emob30dg/Voice.pdf Best practice for voice is -67 dBm cell edge, 25 dB SNR, 15-20% overlap, etc. https://www.cisco.com/c/en/us/td/docs/wireless/technology/vowlan/troubleshooting/vowlan_troubleshoot/8_Site_Survey_RF_Design_Valid.html#wp1053033

DE is correct

The best-practice guidelines for designing any AP cell recommend setting the cell boundary at –67 dBm,

the available 24 channels make this answer invalid, because of the DFS requirements While 15% of overlap is a recommendation from Cisco No reommendation for 40 MHz Correct answer D + E

Chapter 5 "Applying Wireless Design Requirements" Designing a Wireless Network for Voice and Video "As you plan the band and channel assignment for each AP, try to leverage the 5GHz band as much as possible. There are more non-overlapping channels there and much less chance of interference from non-Wi-Fi devices than in 2.4GHz. A common practice is to use the U-NII-1 and U-NII-3 channels, while avoiding U-NII-2 and U-NII-2 Extended channels because of DFS requirements."

I agree it's C and D

Is is D and E 40Mhz is useless for voice and it is limiting the number of channels available. There is 25 channels available in 5Ghz but UNII-2 is under DFS regulation so unusable for voice deployment.

To reduce channel utilization in the 2.4 GHz band, Cisco recommends moving clients to 5 GHz. https://www.cisco.com/c/en/us/td/docs/wireless/controller/8-1/Enterprise-Mobility-8-1-Design-Guide/Enterprise_Mobility_8-1_Deployment_Guide/Chapter-9.html

Def D&Ehttps://www.cisco.com/en/US/docs/solutions/Enterprise/Mobility/emob30dg/Voice.pdf

-67 dBm cell boundary is a requirement for Voice. Channel-bonding is a site-dependent capability and should at least be considered. ------- - 19 dBm is incorrect. dBm is a compared value. As it is the separation between 2 AP's, it should have been stated as 19 dBm. And in most deployments this is not achievable. The number of non-overlapping channels is regulatory domain dependent. The cell overlap should be 20% instead of 15%

Both D and E are explain here : https://www.cisco.com/en/US/docs/solutions/Enterprise/Mobility/emob30dg/Voice.pdf

Cisco will not provide answers that involve regulatory domain, so it is not option C. B is not an option because using 20MHz is enough for any voice deployment. Option D and E are correct because both are specified in the Cisco PDF here: https://www.cisco.com/en/US/docs/solutions/Enterprise/Mobility/emob30dg/Voice.pdf

According to Cisco ENWLSD Course, it is B and D. 20 MHz BW recommended for only voice use cases (24/25 channels)

Arent there 25 channels in 5Ghz?