Designing The Wireless Lan; Planning Channel Usage; Ghz (802.11A/N/Ac) - Cisco 8800 Series Deployment Manual

The Cisco IP Phone 8861 primarily utilizes active mode, but if there is an associated client that is in power save mode, then all
multicast packets will be queued until the DTIM period.
With multicast, there is no guarantee that the packet will be received the by the client.
The multicast traffic will be sent at the highest mandatory / basic data rate enabled on the access point, so will want to ensure
that only the lowest enabled rate is configured as the only mandatory / basic rate.
The client will send the IGMP join request to receive that multicast stream. The client will send the IGMP leave when the
session is to be ended.
The Cisco IP Phone 8800 Series supports the IGMP query feature, which can be used to reduce the amount of multicast traffic
on the wireless LAN when not necessary.
Ensure that IGMP snooping is also enabled on all switches.
It is recommended to enable Multicast Direct in the Cisco Unified Wireless LAN Controller.
Note: If using Coexistence where 802.11b/g/n and Bluetooth are being used simultaneously, then multicast voice is not
supported.

Designing the Wireless LAN

The following network design guidelines must be followed in order to accommodate for adequate coverage, call capacity and
seamless roaming for the Cisco IP Phone 8800 Series.

Planning Channel Usage

Use the following guidelines to plan channel usage for these wireless environments.

5 GHz (802.11a/n/ac)

5 GHz is the recommended frequency band to utilize for operation of the Cisco IP Phone 8800 Series.
The Cisco IP Phone 8800 Series supports Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC) from
802.11h, which are required when using channels operating at 5.260 - 5.720 GHz, which are 15 of the 24 possible channels.
DFS dynamically instructs a transmitter to switch to another channel whenever radar signal is detected. If the access point
detects radar, the radio on the access point goes on hold for at least 60 seconds while the access point passively scans for
another usable channel.
TPC allows the client and access point to exchange information, so that the client can dynamically adjust the transmit power.
The client uses only enough energy to maintain association to the access point at a given data rate. As a result, the client
contributes less to adjacent cell interference, which allows for more densely deployed, high-performance wireless LANs.
5 GHz channels overlap their adjacent channel, so there should be at least 1 channel of separation for adjacent access points.
Need to ensure there is at least 20 percent overlap with adjacent channels when deploying the Cisco IP Phone 8800 Series in the
802.11a/n/ac environment, which allows for seamless roaming. For critical areas, it is recommended to increase the overlap
(30% or more) to ensure that there can be at least 2 access points available with -67 dBm or better, while the Cisco IP Phone
8800 Series also meets the access point's receiver sensitivity (required signal level for the current data rate).
Cisco IP Phone 8800 Series Wireless LAN Deployment Guide
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