What is a router ?

Definition: Routers are small physical devices that join multiple networks together. Technically, a router is a Layer 3  gateway  device, meaning that it connects two or more networks and that the router operates at the network layer of the OSI model.

What is a router ?

Home networks typically use a wireless or wired Internet Protocol (IP) router, IP being the most common OSI network layer protocol. An IP router such as a DSL or cable modembroadband router joins the home's local area network (LAN) to the wide-area network (WAN)of the Internet.

By maintaining configuration  information  in a piece of storage called the routing table, wired or wireless routers also have the ability to filter traffic, either incoming or outgoing, based on the IP addresses of senders and receivers. Some routers allow a network administrator to update the routing table from a Web browser interface. Broadband routers combine the functions of a router with those of a network switch and a firewall in a single unit.

 

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What Is a Default Gateway?

Question: What Is a Default Gateway?

You will sometimes see the term default gateway on network configuration screens in Microsoft Windows.

Answer: In computer networking, a default gateway is the device that passes traffic from the local subnet to devices on other subnets. The default gateway often connects a local network to the Internet, although internal gateways for local networks also exist.

What Is a Default Gateway?

  Internet default gateways are typically one of two types:

• On home or small business networks with a broadband router to share the Internet connection, the home router serves as the default gateway.
   
• On home or small business networks without a router, such as for residences with dialup Internet access, a router at the Internet Service Provider location serves as the default gateway.

Default network gateways can also be configured using an ordinary computer instead of a router. These gateways use two network adapters, one connected to the local subnet and one to the outside network. Either routers or gateway computers can be used to network local subnets such as those in larger businesses. In Microsoft Windows, the IP address of a computer's default gateway can be accessed in the ipconfig or 'winipcfg' utilities (see sidebar).

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broadband router

Definition: A broadband router combines the features of a traditional network switch, anetwork firewall, and a DHCP server. Broadband routers are designed for convenience in setting up home networks, particularly for homes with high-speed Internet service. Besides easier sharing of a home Internet connection, broadband routers also enable sharing of files, printers and other resources among home computers.

broadband router

A broadband router utilizes the Ethernet standard for wired connections. Traditional broadband routers required Ethernet cables be run between the router, the broadband modem, and each computer on the home network. Newer broadband routers also incorporate wireless networking capability utilizing the Wi-Fistandards.

Several manufacturers offer broadband router products to consumers. Features that differentiate broadband router products include the specific Wi-Fi and Ethernet standards supported along with additional performance and security features.

→ See also -  Before You Buy a Home Broadband Router 

Also Known As: residential gateway, home gateway

 

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Before You Buy a Home Broadband Router

Broadband routers are the central feature of many home networks. These routers support sharing of cable modem or DSL Internet connections. They also include various network security features like firewall capability. Before you buy a broadband router for your home, factor the following criteria into your decision.

Before You Buy a Home Broadband Router

Wired or Wireless

All major broadband router manufacturers offer both wired and wireless Ethernet products. Price differences between the two have shrunk considerably in the past year. However, to go wireless, each home computer requires special network adapters that are not cheap. If you do go wireless, keep in mind the popular 802.11b wireless Ethernet standard is being phased out in favor of 802.11g.

Network adapters

802.11b

802.11g

Port Configuration

Entry-level wired broadband routers feature four ports for connecting four home computers. Four ports may not be adequate to support larger families or neighborhood get-togethers like "LAN parties." Five-port models add an extra "uplink" port that allows you to expand your network later, and to support a mix wired and wireless computers. Eight-port routers are best if you need the extra capacity now.

Brand

The many brands of broadband routers vary greatly in their pricing, reputation for quality manufacturing, warranty terms, technical support, and aesthetic "look and feel." There is no one "killer brand" for home broadband routers. When choosing a product, factor in the opinions of friends and coworkers who already own a broadband router. Beware of false claims from strangers on the Internet.

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Network Firewall Security

Definition: A network firewall protects a computer network from unauthorized access. Network firewalls may be hardware devices, software programs, or a combination of the two.

Network Firewall Security 

Network firewalls guard an internal computer network (home, school, business intranet) against malicious access from the outside. Network firewalls may also be configured to limit access to the outside from internal users.

Network Firewalls and Broadband Routers

Many home network router products include built-in firewall support. The administrative interface of these routers include configuration options for the firewall. Router firewalls can be turned off (disabled), or they can be set to filter certain types of network traffic through so-called firewall rules.

Network Firewalls and Proxy Servers

Another common form of network firewall is a proxy server. Proxy servers act as an intermediary between internal computers and external networks by receiving and selectively blocking data packets at the network boundary. These network firewalls also provide an extra measure of safety by hiding internalLAN addresses from the outside Internet. In a proxy server firewall environment, network requests from multiple clients appear to the outsider as all coming from the same proxy server address.

Also Known As: proxy, gateway

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OSI Model - Open Systems Interconnection model

Definition: The OSI model defines internetworking in terms of a vertical stack of seven layers. The upper layers of the OSI model represent software that implements network services like encryption and connection management. The lower layers of the OSI model implement more primitive, hardware-oriented functions like routing, addressing, and flow control.

OSI Model - Open Systems Interconnection model

In the OSI model, data communication starts with the top layer at the sending side, travels down the OSI model stack to the bottom layer, then traveses the network connection to the bottom layer on the receiving side, and up its OSI model stack.

The OSI model was introduced in 1984. Although it was designed to be an abstract model, the OSI model remains a practical framework for today's key network technologies like Ethernet and protocols like IP.

Also Known As: Open Systems Interconnection (OSI) reference model, OSI seven layer model

Examples:

Internet Protocol (IP) corresponds to the Network layer of the OSI model, layer three. TCP and UDP correspond to OSI model layer four, the Transport layer. Lower layers of the OSI model are represented by technologies like Ethernet. Higher layers of the OSI model are represented by application protocols like TCP and UDP.

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Networking With A Router

A network router is a small electronic device that allows you build a home network simply. The home router serves as the core or "centerpiece" of the network to which computers, printers and other devices can be connected. Networking with a router helps you to (for example):

Networking With A Router

share files between computers

share an Internet connection between computers

share a printer

connect your game console or other home entertainment equipment to the Internet

Routers are not necessarily required to build a network. For example, you can connect two computers directly to each other with just a cable (or without wires in some cases). Home routers offer convenience and easier maintenance as your network grows.

Related - Connecting Two Home Computers

Choosing a Network Router

You can choose from among several different types of home network router products. The two most common types in popular usage are the 802.11b and 802.11g WiFi models. 802.11g is the newer technology, but 802.11b routers often can do the job for an even lower cost.

More - Choosing a Wireless Router

Gear - Top 802.11ac Wireless Routers

Gear - Top 802.11n Wireless Routers

Gear - Top 802.11g Wireless Routers

Installing a Network Router

Network routers receive their power from an ordinary home electrical socket. When powered on, lights (LEDs) signify the unit is operating.

Network routers must be carefully configured when they are first installed. Like computers and other devices on the home network, routers must be set up with IP addresses. Routers also offer optional (but strongly recommended) security features.

Routers contain built-in software to enable setup. You access this software through your Web browser on any computer connected to the router.

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