onservative estimate of initial traffic level, then monitoring the traffic and adjusting capacity to levels consistent with acceptable utilization and growth plans. Backbone transport varies based on requirements and usually comes with significant and critical services attached. For example, the access facility is a dumb, point-to-point, TDM unchannelized facility. But routed networks include services such as routing and configuration protocols, IP address provision, service configuration and manage- ment that depend on processing functions resident in edge and core routers. It naturally follows that the owner of the core backbone equipment should provide these services. LOCAL AREA OR LOCAL AREA NETWORK CONNECTION LAN as used in this document means specific versions of IEEE 802.1, 802.3, and other standards applicable to network interfaces, refer- enced in a manufacturer's product documentation. Terms such as PRACTICAL IP AND TELECOM FOR BROADCAST ENGINEERING AND OPERATIONS 10BT, 10/100BT, Fast Ethernet, Gigabit Ethernet, and 1000BT are informal references. Where doubt exists, it is recommended that designers rely on direct personal knowledge of formal IEEE or other applicable standards and seek clarification of applicability to a particular manufacturer's products from a representative know- ledgeable about design details of the equipment. Each standard Ethernet interface is assigned a unique 48-bit identifi- cation code by the original equipment manufacturer pursuant to a registry agent defined in IEEE standards. This code is referred to as a MAC address (meaning Media Access Control). The MAC address is inserted into Ethernet packets and enables devices connected to the LAN to establish sessions and route packets around or outside the LAN. When packets are routed outside the LAN, it's likely the MAC address is translated to an IP address, which becomes the basis for IP network transport. MAC and IP addresses are the functional equiva- lent of telephone numbers. Ethernet interfaces enable user access, and conne