Voice over Wireless LAN Solution Guide v1.0 December 2005
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the proper signaling server. This can of course get cumbersome if there are a large number of
users who travel.
3.3 DNS server
Another way that a DAP that is separated from a WSS 2300 by a router can find a WSS 2300 is
DNS. If the DAP does not receive a DHCP option 43 containing the IP address of a WSS 2300,
then the AP will attempt to resolve through DNS the hostname wlan-switch.domain.com, where
domain.com is the option 15 string provided by the DHCP server. So the DHCP server provides
the domain name and wlan-switch is appended to the domain name.
As mentioned previously, DHCP can return a hostname, in which case the AP will attempt to
resolve the specified hostname.domain.com through DNS. The returned IP address will
correspond with a WSS 2300 so that the AP can learn the IP address of its proper WSS 2300.
3.4 TFTP server
Each WLAN Handset 2210/11/12 and WTM 2245 installation requires a TFTP server. It is used to
provide updated firmware and configuration files to the handsets and WTM 2245. You only need
one TFTP server in the network, and it does not have to be collocated with handsets or WTM
2245. Some of the tested TFTP servers include:
3COM TFTP
TFTP32
PumpKIN TFTP
SolarWinds TFTP
TFTPD32
Note that there is a client-dependent aspect to how the handsets function with the TFTP server.
This means that how well a server works with the handsets may vary between code versions on
the handset.
Handsets can be configured to not contact the TFTP server upon boot up by configuring
255.255.255.255 as the IP address for the TFTP server (either directly in the handset or through
the DHCP option). The WTM 2245 can be configured to not contact the TFTP server by changing
the TFTP server address to “none” in the configuration.