Modern local network must perform the following tasks:
- To provide the advanced telecommunications services to employees of different companies, organizations, departments, and so on;
- To meet the growing needs of a variety of information services that require high-speed data transmission channels;
- To integration the existing subnets communication (including telephone) and optimization of the process of technological constraints;
- To minimizing the cost of construction and maintenance of their systems;
- To provide increasing demands for quality information and telecommunication services, including the availability of information resources;
- To meet the requirements for ensuring information security and privacy of transmitted data.
/> These points rise up a question about the construction of networks on the basis of one technology - data networks with integrated services and multiservice networks. Clients of the network should be able to at any time or request a particular service, or abandon it by going to a more economical and convenient for the customer type of service and its mode.
The network designing process includes the following steps:
Selection of optimal network access technology;
Local network mapping;
Selection of the necessary equipment;
Selection of software.
On the current stage of telecommunication systems development the wireless technology are becoming more and more common. Although wireless technology is still inferior in speed wired transmission system, it has several advantages such as the absence of spatial constraints nodes and expensive cables.
Wireless local area networks (WLAN) have the following advantages over cable networks (LAN):
- They provide the possibility of unlimited movement in the coverage area of WLAN, preserving access to corporate information resources;
- The possibility of WLAN installation where a conventional installation cabling is difficult or impossible (in a historical building or the open countryside);
- The ability to create mobile mobile LAN;
- High speed WLAN deploy;
- Close to zero cost of ownership WLAN.
When designing a LAN (WLAN) it is necessary to consider the features of the wireless technologies protocols, the mobile nodes behavior, protection, communication quality (QoS) and applications used by wireless clients (Olifer et. al 2006).
The most optimal solution when choosing a wireless standard is the use of network equipment 802.11n standard. This standard is one of the most advanced, high bandwidth, noise immunity and protected.
An important component of this network will be the introduction to its VoIP service. VoIP or IP-telephony is a technology that allows using the Internet or any other IP-based network for conducting calls and send faxes in real time. The IP-telephony gateway provides voice communication on IP-networks. The general principle of telephone gateways (IP-telephony) is that on the one hand the gateway is connected to the phone lines and thus can connect to any phone in the world and on the other hand the gateway is connected to an IP-network which allows communicating with any computer in the world. The gateway receives the telephone signal, digitizes it (if it is not initially digital) substantially compresses divides into packets and sends them via IP-based network to the destination using the protocol IP.
Another important component of the network is access to the Internet (WAN). Typically, this function goes to the router, a device for communication between different networks¸ which includes a gateway to access the WAN.
LAN equipment is divided into active and passive (Korowajczuk 2011). The active equipment components are:
Wireless Access Point
gateway access to the WAN;
Passive equipment includes:
network cables (copper, fiber optic);
The above given information allows us to build LAN structures shown on Fig.1.
The main element of this network is a wireless router WLAN0. It serves as the gateway to the WAN network, mobile subscribers access point (Laptop 0-2) and the router, which is connected to the switch Switch0. To switch is connected to personal computers (PC 0-2), IP-telephones (IP-phone 0-1) and the VoIP device, which in its turn is connected to the analog telephone. The passive equipment used in the network are direct connection cables 7 10base-T-type, one cable 10base-T-type for cross connection (crossover) and one telephone cable.
It is recommended to use a LAN technology VLAN (Virtual LAN) to ensure the optimum network performance. This is a group of devices having the opportunity to interact directly with each other at the link layer, although physically they can be connected to different network switches.
The next step of network designing is building a network installation and configuration software. In this case, you need to configure the wireless router, the user node network and to configure a separate IP-telephony network.
When properly configured, the router simply connects the user equipment to the network and the setting will be done automatically.
For the design of IP-telephony network is necessary:
- To choose the server IP-telephony and arrange to be connected to an existing local area network;
- To choose telephone operator and arrange wired telephone lines;
- To select the operator of Internet telephony and connect to it through the existing network;
- To configure the internal phone numbers of employees on the IP-telephony server;
- To connect your phone to your office network;
- To analyze, select and configure the softphone software;
- To organize main and backup power supply selected products.
Korowajczuk, L. (2011). LTE, WIMAX, and WLAN network design, optimization and performance analysis. Chichester, West Sussex, U.K.: Wiley.
Olifer, N., & Olifer, V. (2006). Computer networks: Principles, technologies, and protocols for network design. Chichester, England: John Wiley & Sons.