154 CHAPTER 9: C ONFIGURING IP TELEPHONYIP On-the-FlyConfigurationThe NBX system must be configured differently in each of the following IPOn-the-Fly situations:■ All telephones and devices are on the same subnetwork as the CallProcessor.You do not need to use IP in this environment. Devices always useEthernet (Layer 2) communications, and the Call Processor neverneeds to give out an IP address.■ Some telephones are on separate subnetworks.If you use a DHCP server, verify that the server has enough IPaddresses to handle the number of telephones and devices in the NBXsystem. Optionally, you can configure the DHCP server to pass the IPaddress of the NCP to DHCP client devices. For an example, seeAppendix C, “Configuring Option 184 on a Windows 2000 DHCPServer,” in the NBX Administrator’s Guide.If you are not using DHCP, you must use the NBX NetSet utility toconfigure a block of IP addresses for use by IP On-the-Fly devices, andconfigure the NCP’s IP address into each telephone that will be locatedon a remote subnetwork.Devices on the same subnetwork as the NCP are given an IP addressonly if they need to communicate with a device that is on a differentsubnet. See “Configuring IP On-the-Fly” on page 156.3C10165D E1 and 3C10116D T1 Digital Line Cards do not support theNBX IP On-the Fly feature. If your system uses IP On-the-Fly, then youmust assign a static IP address to the card or use DHCP to assign an IPaddress to the card, even if the card will be installed on the same subnetas the NCP.Providing the NCP IPAddress to DevicesTo provide the IP address of the NCP to devices on other subnetworks,use one of these methods:■ Program the IP address of the NCP directly into each telephone usingthe telephone key pad. See Chapter 10, Troubleshooting, in the NBXAdministrator’s Guide for instructions on how to use the telephonesLocal User Interface (LUI) utility.■ Program a custom DHCP option on the DHCP server and configure theserver to pass the IP address of the NCP to remote devices through thestandard DHCP configuration process.
