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, referenced in a manufacturer’s product documentation. Terms such as 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 knowledgeable about design details of the equipment.

Each standard Ethernet interface is assigned a unique 48-bit identification 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 equivalent of telephone numbers.

Ethernet interfaces enable user access, and connectivity between system components and peer platforms. The minimum required configuration is a simple Ethernet LAN segment. In more complex arrangements, the LAN segment provides access to MAN and WAN network facilities and services. If the network facilities are designed and implemented properly, use of any application on the system by any user with network access and user privileges is possible.

Most operating systems including LAN interface drivers permit manual or automatic, so-called plug-and-play configuration of the network interface. Microsoft Windows 2000 Workstation and Server and Windows XP Professional workstation include real-time communications client software. If the NIC is capable of being configured for QOS, then end-to-end real-time content transport is possible if it is configured. This is the first step in gaining end-to-end real-time content transport across the network between server platforms.

LAN Telephony

Local access network (LAN) telephony (sometimes called TeLANophy) use LAN systems to transport voice communications. LAN telephone technology is an evolution of voice over IP (VoIP) and the rapid acceptance of virtual private networks (VPN’s) as an alternative to leased line private networks. The ability to share data networks with voice systems offers significant cost reduction for telephone services.

Figure 1 shows a LAN telephony system. This diagram shows that a LAN telephone system consists of LAN telephones, a data network, a LAN call processing system, and a voice gateway to the PSTN. LAN telephones convert audio into digitized packets that are transferred on the LAN to the call processing computer (CTI system). Each LAN telephone has its own network data address. The call processing system communicates with LAN telephones over the same high-speed LAN data network that communicates with computers. When calls are received from the PSTN, the call processing system looks in the database to find the associated LAN telephone address (data address) and this address is used to alert the LAN telephone of an incoming call. When calls are originated from the LAN telephone, the dialed telephone number is passed to the call processing system. This system determines if the call is routed within the data network or if the voice gateway must be used to connect the call to the PSTN.


Figure 1: LAN Telephony