Nortel Networks NN43001-504 - Manual (Page 64)

64 Planning
To gain this type of predictability, engineer the maximum calls per AP based
on 1 Mb/2 Mb rate selections in the handsets, configure that number as the
call limit on the WLAN IP Telephony Manager 2245, and then configure the
actual rate of the handsets (on the WLAN IP Telephony Manager 2245) to
Automatic. That way, the WLAN is engineered for the worst case, but in
optimal conditions, more throughput is left over for other devices to use,
because the handsets use higher data rates.
To summarize, do not use the 1 Mb/2 Mb option, even if the network is
engineered to that type of coverage.
Gateway and timing function
WLAN IP Telephony Managers 2245 provide both the connection or
gateway to the Call Server for the wireless handsets, and the timing function
for active calls. This gateway function is distributed across the WLAN IP
Telephony Manager 2245 group.
The number of active WLAN IP Telephony Managers 2245 is determined
dynamically. Whenever a WLAN IP Telephony Manager 2245 is added to or
removed from the system, the distribution of timing function for active calls,
as well as the gateway function, is affected.
Roaming and handover
Roaming is the ability of the wireless handset to go anywhere in the WLAN
Extended Service Set RF signal coverage area, and to make and receive
calls. Handover is the ability of the wireless handset to maintain an active
call without interruption while moving within a WLAN Extended Service Set
(ESS) RF signal coverage area of a WLAN. This means that the wireless
handset hands over the WLAN RF signal from AP to AP without interrupting
the data stream.
Access points on the same subnet
The handset can perform handover and roaming across SVP-compliant
APs that reside on the same subnet as the wireless handset and WLAN
IP Telephony Manager 2245 group.
Mobility across different subnets when using DHCP
If a WSS is not in use and the wireless handset IP address is acquired
through DHCP, the wireless handset must be powered down and powered
up when entering a new subnet. This enables functionality of the wireless
handset when entering the WLAN RF signal coverage area of a different
WLAN IP Telephony Manager 2245 group on a different subnet. After the
wireless handset establishes communication within the Extended Service
Set Identifier (ESSID) of the new WLAN, obtains another IP address from
the DHCP server, and checks in with the group master, normal functionality
Nortel Communication Server 1000
WLAN IP Telephony Installation and Commissioning
NN43001-504 01.02 Standard
Release 5.0 15 June 2007
Copyright © 2004-2007, Nortel Networks
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