Cisco Systems 71642 Network Router User Manual


 
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If the telephony server is available, initiate a call with a stationary device to the badge.
Continually check voice quality while you traverse the total wireless coverage area. If the
voice quality is insufficient, perform these tasks:
Listen for all unacceptable changes in voice quality and take note of the location and radio
values on your laptop and CQ values from the badge.
Watch and listen for the badge to roam to the next access point.
Note the other available access points in the site survey to check coverage and interference.
Make adjustments to access point placement and settings to fine−tune the WLAN, and perform these
checks to ensure voice quality:
Use the site survey tools and verify that there is no more than one access point per channel
with an RSSI value greater than 35 in any given location. Ideally, all other access points on
the same channel should have RSSI values as low as possible (preferably less than 20). At the
border of the coverage area where the RSSI is 35, the RSSI for all other access points on the
same channel should ideally be less than 20.
Use the site survey tools to verify that there are at least two access points (total, on separate
channels) visible in all location with sufficient signal strength.
Check that the access points in a given roaming area are all on a Layer 2 network.
Common Roaming Issues
These roaming issues can occur:
The badge does not roam when placed directly under the access point.
The badge is most likely not reaching the roaming differential thresholds for the received signal
strength indicator (RSSI) and channel utilization (CU). Adjust the Transmit Power Threshold form the
WLC.
The badge does not receive beacons or probe responses from the access point.
The badge roams too slowly.
The Badge Loses Connection to the Network or Voice Service is Lost
when Roaming
Check authentication for a possible WEP mismatch.
The badge does not send out IGMP joins or the network sends IGMP queries during a roam.
Therefore, the Vocera broadcast function fails during a Layer 2/Layer 3 roam.
The badge is capable of seamless Layer 2 roaming only (unless a Layer 3 mobility mechanism is
configured). Ensure that the new WLC is not serving a different IP subnet.
Verify that the associated access point/controller has IP connectivity to the Vocera Communication
Server.
Check the RF signal strength and badge CQ values.
Badge Loses Voice Quality while Roaming
Check for low RSSI on the destination access point.
Channel overlap might be insufficient. The badge must have time to hand off the call smoothly before
it loses its signal with the original access point.
The signal from the original access point might be lost.