Nortel Networks M3310 - Manual (Page 65)

Digital Telephone IP Adapter Installation and Administration Guide 65
January 2005 Planning for installation
It is possible, when using a Digital Telephone IP Adapter unit behind a NAT
device, that prolonged periods of silence cause the NAT translation table entries
to clear and drop the audio path. An example of this is a remote user listening to
a conference call with the user’s digital telephone set on mute. After five
minutes (the default NAT translation table timer on many NAT routers) the
router drops the voice path. The remote user is no longer able to hear the
conference. To restore the NAT table entry and recover the audio path, the
remote user can go off mute and speak into the digital telephone set.
To prevent the NAT translation table from dropping the audio path:
!
configure the translation tables on the NAT router with a large timer value
(for example, two hours)
!
configure a static translation table entry for UDP port 20480
IP deployment
Before deploying your Digital Telephone IP Adapter unit, ensure that you
engineer the IP network properly. You can configure a permanent (Model 1) or
on-demand (Model 2) IP connection. The following guidelines describe
requirements, conditions, and characteristics of each supported IP deployment
option:
Model 1: IP permanent
If using DSL or a cable modem, configure an IP permanent connection.
!
The Digital Telephone IP Adapter unit re-establishes its TCP/IP signaling
session to the RLC once per minute.
!
The Digital Telephone IP Adapter unit supports both static IP and, through
DHCP, dynamic IP addressing
!
Do not configure a remote IP address on the RLC.
!
One virtual private network (VPN) supports multiple Digital Telephone IP
Adapter units.
!
One Network Address Translation (NAT) router supports only one Digital
Telephone IP Adapter unit.
!
One Port number and Network Address Translation (PNAT) router supports
multiple Digital Telephone IP Adapter units.