Cisco Cisco IP Phone 8841 Designanleitung
Cisco Wireless IP Phone 8821 and 8821-EX Wireless LAN Deployment Guide
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The DTIM period is a tradeoff between battery life and multicast performance.
Broadcast and multicast traffic will be queued until the DTIM period when there are power save enabled clients associated to
the access point, so DTIM will determine how quickly these packets can be delivered to the client. If using multicast
applications, a shorter DTIM period can be used.
When multiple multicast streams exist on the wireless LAN frequently, then it is recommended to set the DTIM period to 1.
Broadcast and multicast traffic will be queued until the DTIM period when there are power save enabled clients associated to
the access point, so DTIM will determine how quickly these packets can be delivered to the client. If using multicast
applications, a shorter DTIM period can be used.
When multiple multicast streams exist on the wireless LAN frequently, then it is recommended to set the DTIM period to 1.
Dynamic Transmit Power Control (DTPC)
To ensure packets are exchanged successfully between the Cisco Wireless IP Phone 8821 or 8821-EX and the access point,
Dynamic Transmit Power Control (DTPC) should be enabled.
DTPC prevents one-way audio when RF traffic is heard in one direction only.
If the access point does not support DTPC, then the Cisco Wireless IP Phone 8821 and 8821-EX will use the highest available
transmit power depending on the current channel and data rate.
The access point’s radio transmit power should not have a transmit power greater than what the Cisco Wireless IP Phone 8821
and 8821-EX can support.
Dynamic Transmit Power Control (DTPC) should be enabled.
DTPC prevents one-way audio when RF traffic is heard in one direction only.
If the access point does not support DTPC, then the Cisco Wireless IP Phone 8821 and 8821-EX will use the highest available
transmit power depending on the current channel and data rate.
The access point’s radio transmit power should not have a transmit power greater than what the Cisco Wireless IP Phone 8821
and 8821-EX can support.
Call Capacity
Design the network to accommodate the desired call capacity.
The Cisco Access Point can support up to 27 bi-directional voice streams for both 802.11a/n/ac and 802.11g/n at a data rate of
24 Mbps or higher. To achieve this capacity, there must be minimal wireless LAN background traffic and initial radio frequency
(RF) utilization.
The number of calls may vary depending on the data rate, initial channel utilization, and the environment.
The Cisco Access Point can support up to 27 bi-directional voice streams for both 802.11a/n/ac and 802.11g/n at a data rate of
24 Mbps or higher. To achieve this capacity, there must be minimal wireless LAN background traffic and initial radio frequency
(RF) utilization.
The number of calls may vary depending on the data rate, initial channel utilization, and the environment.
Audio Only Calls
Below lists the maximum number of audio only calls (single bi-directional voice stream) supported per access point / channel.
Max # of
Streams
Audio Codec
Audio
Bit Rate
802.11 Mode
Data Rate
13
G.722 / G.711 64 Kbps
802.11a/n or 802.11g/n +
Bluetooth Disabled
Bluetooth Disabled
6 Mbps
20
G.722 / G.711 64 Kbps
802.11a/n or 802.11g/n +
Bluetooth Disabled
Bluetooth Disabled
12 Mbps
27
G.722 / G.711 64 Kbps
802.11a/n/ac or 802.11g/n
+ Bluetooth Disabled
+ Bluetooth Disabled
24 Mbps or higher
Multicast
When enabling multicast in the wireless LAN, performance and capacity must be considered.
If there is an associated client that is in power save mode, then all multicast packets will be queued until the DTIM period.
The Cisco Wireless IP Phone 8821 and 8821-EX utilize active mode primarily, 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.
If there is an associated client that is in power save mode, then all multicast packets will be queued until the DTIM period.
The Cisco Wireless IP Phone 8821 and 8821-EX utilize active mode primarily, 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.