3Com 3C10200 NBX Installation Guide - Page 180

180 CHAPTER 10: CONFIGURING IP TELEPHONY IP Telephony Overview You can integrate the NBX system into any network infrastructure because it can operate at either Layer 2 (Ethernet) or Layer 3 (IP). For information on configuring an NBS system to run SIP mode, see the NBX Administrator's Guide. If all the telephones in your office connect to the same Local Area Network (LAN) and you do not have your LAN segmented into subnetworks, there is little reason to implement IP telephony. Even if your network includes a few subnetworks, you can configure the routers to pass NBX Ethernet frames and avoid the need for IP operation. In a more widely distributed setting with several subnetworks or with a part of the network distributed over a Wide Area Network (WAN), IP telephony may be required. This section covers these topics: ■ Implementing IP ■ Standard IP Configuration ■ IP On-the-Fly Configuration ■ Providing the NCP IP Address to Devices Implementing IP You can implement IP in one of two ways: ■ Standard IP All devices receive an IP address, either from a Dynamic Host Configuration Protocol (DHCP) server or through manual assignment. ■ IP On-the-Fly Telephones and other devices on the same subnet as the NCP communicate with other devices on that subnet using Ethernet frames so they do not need IP addresses. Devices receive an IP address only when they need to communicate with a device on a different subnet. The system administrator specifies a list of IP addresses using the NBX NetSet utility. When a local device needs an IP address, the system assigns one from the list. Remote devices receive their IP addresses either through a DHCP server or through manual assignment.