Term of the Moment
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Redirected from: network router
Definition: router
A device that forwards data from one network to another. Based on an internal routing table and the address of the destination network in the incoming packet, the router determines whether to send the packet out or keep it within the network. The traffic traversing a router is formatted in a routable protocol, the global standard being TCP/IP, or simply IP (see TCP/IP and routable protocol).
At Home
In the home or small office, a "wireless router" or "wireless gateway" is used to manage Internet traffic. The "router" contains a built-in Ethernet switch and Wi-Fi access point, but requires a modem to connect to the ISP (see wireless router). The wireless "gateway" includes the modem (see cable/DSL gateway). The Ethernet switch in the wireless router typically has four Ethernet ports for wired computers and printers.
In a Company
Routers in a company are dedicated to packet forwarding only and connect to stand-alone modems wired to Internet providers and one or more Wi-Fi access points for employees. They are also connected to multiple Ethernet switches that can reach any number of number of computers and printers. See Ethernet switch and access point.
Routers in the Core
Within a large enterprise, routers separate local area networks (LANs) into subnetworks (subnets) to balance traffic within workgroups and to filter traffic for security purposes and policy management. They also forward packets between the company's LANs, private external networks (WANs) and the Internet. Factors such as traffic load, external line costs and congestion may be taken into consideration to determine which port to forward to. See LAN and WAN.
A Huge Range of Prices
Routers range from $50 to tens of thousands. Home wireless routers from companies such as D-Link, NETGEAR and Grandstream are the least expensive, while enterprise and Internet core routers from companies such as Cisco, Brocade and Huawei are the most costly. See packet switching, Ethernet, SONET, edge router and collapsed backbone.
A Windows PC Can Be a Router
Routers are normally dedicated communications devices; however, a Windows PC can be turned into a router with NAT32 software.
Router Terminology
Routers used to be called "gateways," which is why the term "default gateway" means the router in the network (see default gateway). For more details on the routable protocol layer, see OSI model and TCP/IP abc's. See layer 3 switch, route server, router cluster and routing protocol.
Route Forwarding
Cisco Routers
At Home
In the home or small office, a "wireless router" or "wireless gateway" is used to manage Internet traffic. The "router" contains a built-in Ethernet switch and Wi-Fi access point, but requires a modem to connect to the ISP (see wireless router). The wireless "gateway" includes the modem (see cable/DSL gateway). The Ethernet switch in the wireless router typically has four Ethernet ports for wired computers and printers.
In a Company
Routers in a company are dedicated to packet forwarding only and connect to stand-alone modems wired to Internet providers and one or more Wi-Fi access points for employees. They are also connected to multiple Ethernet switches that can reach any number of number of computers and printers. See Ethernet switch and access point.
Routers in the Core
Within a large enterprise, routers separate local area networks (LANs) into subnetworks (subnets) to balance traffic within workgroups and to filter traffic for security purposes and policy management. They also forward packets between the company's LANs, private external networks (WANs) and the Internet. Factors such as traffic load, external line costs and congestion may be taken into consideration to determine which port to forward to. See LAN and WAN.
A Huge Range of Prices
Routers range from $50 to tens of thousands. Home wireless routers from companies such as D-Link, NETGEAR and Grandstream are the least expensive, while enterprise and Internet core routers from companies such as Cisco, Brocade and Huawei are the most costly. See packet switching, Ethernet, SONET, edge router and collapsed backbone.
A Windows PC Can Be a Router
Routers are normally dedicated communications devices; however, a Windows PC can be turned into a router with NAT32 software.
Router Terminology
Routers used to be called "gateways," which is why the term "default gateway" means the router in the network (see default gateway). For more details on the routable protocol layer, see OSI model and TCP/IP abc's. See layer 3 switch, route server, router cluster and routing protocol.
Routing tables hold the data for making forwarding decisions. Although this is a simple example, routing tables become very complex. Static routing uses fixed tables, but dynamic routing uses routing protocols that let routers exchange data with each other.
For years, Cisco has been the leading router vendor, and these high-end, carrier-grade models process many millions of packets per second (pps). (Image courtesy of Cisco Systems, Inc.)