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Computer network gateway
Thursday, 31 August 2006

A gateway is a combination of hardware and software that translates between two different protocols and acts as the connection point to the Internet. The Internet is a global network of computer networks. Computers attached to the Internet can communicate by sending messages to each other via the Internet. Computer interconnection and communications systems are generally referred to as networks. Networks are typically classified according to their geographical extent as local area networks (LANs), metropolitan area networks (MANs) and wide area networks (WANs). In a LAN, the computers or devices are typically connected together within a "local" area such as a home, office, or group of offices. In a WAN, the computers or devices are typically separated by a greater distance and are often connected via telephone/communication lines, radio waves, or other suitable means of connection. The Internet gateway server for the LAN is typically assigned manually by a user or administrator of the LAN. The Internet gateway server is usually used as the primary and only computing device for connecting the LAN to the Internet.

A computer network is a collection of interconnected computing devices that can exchange data and share resources. A network's protocol specifies a common set of rules and/or signals, such as Ethernet or Token Ring, which the networked devices use to communicate with each other. Each network must have associated with it a well defined language or protocol to enable the respective computers on the network to be able to communicate. Different networks, however, often use different protocols such that computers on one network may not be able to communicate with computers on another network without the assistance of a device or process to translate between the two protocols. A gateway is such a machine that performs the translation between two disparate protocols. Gateways perform code and protocol conversion to facilitate traffic between data highways of differing network architecture. At present, the gateway location protocol (GLP) as a method for linking the plurality of address translating servers has been started to be examined. The GLP is a protocol used to reduce a load on a server and exchanges address information so that a plurality of servers holds the same information. A VTOA packet voice gateway (PVG) is a gateway system that interconnects circuit switched network components to an ATM core network.

The internet is a communications system that routes packets based on internet addresses. In a typical internet communication, a user exchanges internet packets with an internet gateway over a local telephone line or local area network. The computing devices communicate data by dividing the data into small blocks called packets, which are individually routed across the network from a source device to a destination device. The destination device extracts the data from the packets and assembles the data into its original form. Gateways route packets to other gateways until they can be delivered to the final destination directly across one physical network. The internet gateway transfers the packets to the internet where internet routers forward the packets based on the internet address. The packets matriculate through a series of routers until they reach a destination server or another internet gateway. A wireless gateway manages various networks and devices to make them practicably accessible to a subscribing wireless device, as well as making available network content such as images, video and audio files from content sources such as the Internet, an intranet, search engine services, etc.

Recently, as communication equipment and techniques are being progressed, the voice communication and the data communication are made through a single communication network. Gateways are the indispensable components in order to achieve multimedia communications between terminals connected to heterogeneous networks that use different protocols and have different network characteristics. Gateways are key components in every IP telephony infrastructure. IP telephony uses the Internet for real-time audio communications where two or more participants can carry a conversation. The IP telephony is governed by the data network communications standard, known as the Internet protocol, that allows voice to ride on the data network. Gateways offer the advantage of IP telephony by bridging between the traditional telephone network and the Internet. For real-time communications through the Internet, gateways provide audio conversion and perform call setup and termination. The gateway encodes, compresses and packages the voice information originating and transmits these packets on the Internet and vice versa. In addition to this, these gateways exchange control information across the Internet. The control information contains information to set up the actual end-to-end call.

A network gateway act as a firewall is that filters packets and separates a proprietary corporate network, such as an Intranet, from a public network, such as the Internet. Network firewalls provide important safeguards for any network connected to the Internet. Firewalls are configured and managed to realize an important security policy for the particular needs of a given company or entity. To protect a local network, a gateway is usually used to connect the local network to a public network. Through the use of network address translation (NAT) techniques, a gateway provides security as a firewall while enabling machines with local IP addresses to access the internet through the unique global address of the gateway. The gateway will receive the packet from the local machine, and substitute its external globally-unique IP address and a new port address into the source fields of the IP and UDP headers. Data packets, which are entering and/or exiting a local network, are screened or filtered in a firewall. In addition to filtering data packets a gateway element may secure data packets transmitted between, for example, certain local networks. In this case the gateway is both a firewall and a VPN (virtual private network) gateway.

A gateway may be installed on a stand-alone device for interfacing devices near the gateway to remote, centralized services. A gateway acts as the interface between proximity local area protocols and wide area protocols, such as TCP/IP (Transmission Control Protocol/Internet Protocol) on the Internet. A gateway also manages its client devices, aggregates their data, and performs other related tasks. Through gateway devices or routers Internet Service Providers (ISPs) or enterprise network providers can permit a wide variety of users access to their networks and to other online services. In the ISP selection type IP network, a gateway apparatus called an LAC (L2TP access concentrator) is installed at a connection point between the regional IP network as an access network and user terminals, and a gateway apparatus called an LNS (L2TP network server) is installed at a connection point between the regional IP network and each of ISP networks. Unlike conventional dial-up internet access, however, gateway devices permit remote users to access various computer networks and on-line services without having a prior service contract or an ongoing relationship with the service provider.

A gateway may consist of devices such as protocol translators, rate converters, impedance matching devices, fault isolators, or signal translators as necessary to provide system interoperability. A gateway is often associated with both a router, which directs the packets of data that arrive at the gateway, and a switch, which furnishes the path in and out of the gateway for a given packet. A home gateway system has a transceiver that is capable of establishing a wireless local loop connection. A voice processing system is coupled to the transceiver. The voice processing system is capable of storing a message from an incoming call. A caller identification processing system is coupled to the transceiver.