Cisco Cisco Prime Network Control System Appliance White Paper

Page 4 of 7

Faster Streaming Video

Video streaming using multicast is improved when legacy data rates are removed because multicast traffic is sent

at the slowest mandatory data rate. Legacy 802.11 clients require a mandatory data rate no faster than 2 Mbps,

and 802.11b clients require a mandatory data rate no faster than 11 Mbps.

Another Cisco recommended feature is media stream multicast direct. If legacy data rates cannot be removed and

your network has multicast applications, configuring multicast direct will transform the multicast data rate packets

into unicast packets that are sent at data rates specific to the client capabilities and range. With multicast direct

configured, an 802.11n smartphone or tablet can receive video streams at 144 Mbps instead of 2 Mbps.

Using Media Session Snooping with SIP CAC with Cius

Media session snooping should be enabled for the Cisco Cius WLAN. The initial release of Cisco Cius supports

802.11e packet marking for voice and video packets but does not make use of TSPEC for Call Admission Control

(CAC). Enabling the Media Session Snooping option makes it possible to have SIP voice and video CAC logic

manage channel bandwidth subscription. CAC for voice and CAC for video work to keep the Wi-Fi channel from

being oversubscribed with client requests for bandwidth. CAC encourages a client that is not granted bandwidth

requests to seek a channel that has adequate bandwidth. Cisco Wireless LAN Controller (WLC) Software Version

7.0 .98.0 or later is recommended for SIP Video CAC.

How to Test Wi-Fi Coverage for Cius

To evaluate your current network coverage suitability for Cisco Cius, it is recommended that you do a walk around

the site with a live call on a similar device, such as an 802.11n-capable smartphone. Smartphones and tablets
have a single antenna support. You don’t want to test with a multiple-input multiple-output (MIMO) client because

the transmit range will be better.

The test should be done with a WLAN/service set identifier (SSID) that is not used for daily operations. This way
the WLAN can be enabled for either 2.4 GHz or 5 GHz. It is important to find the phone’s coverage performance for

both bands. With a test WLAN, the coverage of the site should be checked with only the 2.4-GHz band enabled.

Then repeat the test with only 5-GHz enabled. Cisco ClientLink should be enabled for the tests.

The link quality to the access point is most important. On the Cisco WLC client statistics page, you can check the
strength of the phone’s signal to the access point. The signal strength is reported in dBm in the received signal

strength indicator (RSSI) field. An RSSI value of -67 dBm on the access point indicates that the phone is at the

edge of coverage where you can expect a good mean opinion score (MOS) value. A value of -67 dBm is equally

applicable for 802.11n devices. There still are bandwidth and jitter considerations that will reduce the MOS value,

but from a signal perspective, -67 dBm is the design goal.

A live call to a Cisco desk phone is the best way to evaluate mobile call quality. The desk phone has a real- time

MOS value, packet lost and jitter reporting which can be accessed by looking up the Call Statistics under Device

Settings. A person at the desk phone can hear the call quality and at the same time monitor the statistics on the

desk phone and the Wi-Fi statistics, including RSSI reported on the WLC. In addition, the person at the desk phone

can make notes on a floor plan if there are areas of poor performance.