Cisco Cisco Cius 4G Guide De Conception
Cisco Cius Wireless Deployment Guide
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Roaming
CCKM is the recommended deployment model for all environment types where frequent roaming occurs.
802.1x authentication is required in order to utilize CCKM.
802.1x without CCKM can introduce delay during roaming due to its requirement for full re-authentication. WPA and WPA2
introduce additional transient keys and can lengthen roaming time.
When CCKM is utilized, roaming times can be reduced from 400-500 ms to less than 100 ms, where that transition time from
one access point to another will not be audible to the user.
Cisco Cius supports CCKM with WPA2 (AES or TKIP) or WPA (TKIP or AES).
802.1x authentication is required in order to utilize CCKM.
802.1x without CCKM can introduce delay during roaming due to its requirement for full re-authentication. WPA and WPA2
introduce additional transient keys and can lengthen roaming time.
When CCKM is utilized, roaming times can be reduced from 400-500 ms to less than 100 ms, where that transition time from
one access point to another will not be audible to the user.
Cisco Cius supports CCKM with WPA2 (AES or TKIP) or WPA (TKIP or AES).
Authentication
Roaming Time
WPA/WPA2 Personal
150 ms
WPA/WPA2 Enterprise 300 ms
CCKM
< 100 ms
Cisco Cius manages the scanning and roaming events; Client Roaming parameters in the Cisco Unified Wireless LAN
Controller are not utilized.
Controller are not utilized.
Roaming can be triggered for either of the following reasons.
• RSSI Differential
• Max Tx Retransmissions (not receiving 802.11 acknowledgements from the access point)
• Missed Beacons
• Max Tx Retransmissions (not receiving 802.11 acknowledgements from the access point)
• Missed Beacons
The roaming trigger for the majority of roams should be due to meeting the required RSSI differential based on the current
RSSI, which results in seamless roaming (no voice or video interruptions).
Unexpected roams are triggered either by missing contiguous 802.11 acknowledgements (Max Tx retransmissions) or beacons
from the access point.
For seamless roaming to occur, Cisco Cius must be associated to an access point for at least 3 seconds, otherwise roams can
occur based on packet loss (max tx retransmissions or missed beacons).
Roaming based on RSSI may not occur if the current signal has met the strong RSSI threshold.
RSSI, which results in seamless roaming (no voice or video interruptions).
Unexpected roams are triggered either by missing contiguous 802.11 acknowledgements (Max Tx retransmissions) or beacons
from the access point.
For seamless roaming to occur, Cisco Cius must be associated to an access point for at least 3 seconds, otherwise roams can
occur based on packet loss (max tx retransmissions or missed beacons).
Roaming based on RSSI may not occur if the current signal has met the strong RSSI threshold.
Note: Cisco Cius does not utilize the RF parameters in the Client Roaming section of the Cisco Unified Wireless LAN
Controller as scanning and roaming is managed independently by the phone itself.
Controller as scanning and roaming is managed independently by the phone itself.
Interband Roaming
Cisco Cius defaults to Auto for frequency band mode, which enables interband roaming and gives preference to the strongest
signal. Typically this will give preference to 2.4 GHz over 5 GHz due to 2.4 GHz having a stronger signal in general assuming
the power levels are the same.
At power on, Cisco Cius will scan all 2.4 GHz and 5 GHz channels when in Auto band mode, then attempt to associate to an
access point using the locally configured network settings. In Auto mode, Cisco Cius scans both bands simultaneously
regardless of call state to allow for seamless interband roaming. Cisco Cius will list the neighbors by the current signal strength
where the frequency band is not a factor.
signal. Typically this will give preference to 2.4 GHz over 5 GHz due to 2.4 GHz having a stronger signal in general assuming
the power levels are the same.
At power on, Cisco Cius will scan all 2.4 GHz and 5 GHz channels when in Auto band mode, then attempt to associate to an
access point using the locally configured network settings. In Auto mode, Cisco Cius scans both bands simultaneously
regardless of call state to allow for seamless interband roaming. Cisco Cius will list the neighbors by the current signal strength
where the frequency band is not a factor.
If configured for 5 GHz only or 2.4 GHz only mode, then just those channels are scanned.