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4600 Series IP Telephones
Issue 2.2 April 2005 35
WAN Considerations
QoS is harder on a WAN than a LAN. A LAN assumes no bandwidth concerns. A WAN
assumes a finite amount of bandwidth. Therefore, QoS considerations are more significant
when the IP telephony environment includes a WAN. In addition, there are administrative and
hardware compatibility issues unique to WANs. WAN administration is beyond the scope of this
document.
DHCP and File Servers
The DHCP server provides the following information to the 4600 Series IP Telephone:
● IP Address of the 4600 Series IP Telephone
● IP Address of the Gatekeeper board on the Avaya media server
● IP Address of the TFTP server if applicable, otherwise the HTTP server
● The subnet mask
● IP Address of the router
● DNS Server IP Address
Administer the LAN so each IP telephone can access a DHCP server containing the IP
Addresses and subnet mask listed.
The IP telephone cannot function without an IP Address. The failure of a DHCP server at boot
time leaves all the affected voice terminals unusable. A user can manually assign an IP Address
to an IP telephone. This can cause a problem when the DHCP server finally returns because
the telephone never looks for a DHCP server unless the static IP data is unassigned manually.
In addition, manual entry of IP data is an error-prone process. We therefore strongly
recommend that a DHCP server be available when the IP telephone reboots. If a DHCP server
is not available at remote sites during WAN failures, the IP telephone is not available after a
reboot.
A minimum of two DHCP servers are recommended for reliability. We strongly recommend
that a DHCP server be available at remote sites if WAN failures isolate IP telephones from the
central site DHCP server(s).
The file server provides the 4600 Series IP Telephone with a script file and, if appropriate, new
or updated application software. See Step 3: Telephone and File Server
on page 36 under
Initialization Process
. In addition, you can edit an associated settings file to customize
telephone parameters for your specific environment. See Administering Options for the 4600
Series IP Telephones on page 80.