Term of the Moment
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Definition: router
A device that forwards data between networks. Based on an internal routing table and the destination address, the router either keeps the data within the network or sends the data to the Internet or to another network.
At Home
In a home or small office, a "wireless router" is the primary network device. It contains the routing component, an Ethernet switch for a small number of wired devices (generally three or four) and a Wi-Fi access point that creates a wireless hotspot.
In a Company
Routers in a large company are often dedicated to only forwarding packets to another part of the company. They may connect to one or more Wi-Fi access points for employee hotspots, and they connect to multiple Ethernet switches wired to dozens of computers and printers. See Ethernet switch and access point.
Large Routers
Within large enterprises, 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 forward packets between the company's local networks (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.
Within the Internet
Very large-scale routers do all the packet switching between the national and regional backbones and are typically connected via optical fibers. Measured in millions of packets per second, large routers handle enormous amounts of Internet traffic (see PPS).
A Huge Price Range
Home wireless routers range from $50 to a few hundred dollars, while routers for a large enterprise or an Internet exchange point (IXP) can cost tens of thousands (see IXP). See packet switching, Ethernet, SONET, edge router and collapsed backbone.
Computers Can Be Routers
Routers are normally dedicated devices; however, with the appropriate software, Windows, Mac and Linux PCs can be turned into routers.
Route Forwarding
Cisco Routers
At Home
In a home or small office, a "wireless router" is the primary network device. It contains the routing component, an Ethernet switch for a small number of wired devices (generally three or four) and a Wi-Fi access point that creates a wireless hotspot.
In a Company
Routers in a large company are often dedicated to only forwarding packets to another part of the company. They may connect to one or more Wi-Fi access points for employee hotspots, and they connect to multiple Ethernet switches wired to dozens of computers and printers. See Ethernet switch and access point.
Large Routers
Within large enterprises, 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 forward packets between the company's local networks (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.
Within the Internet
Very large-scale routers do all the packet switching between the national and regional backbones and are typically connected via optical fibers. Measured in millions of packets per second, large routers handle enormous amounts of Internet traffic (see PPS).
A Huge Price Range
Home wireless routers range from $50 to a few hundred dollars, while routers for a large enterprise or an Internet exchange point (IXP) can cost tens of thousands (see IXP). See packet switching, Ethernet, SONET, edge router and collapsed backbone.
Computers Can Be Routers
Routers are normally dedicated devices; however, with the appropriate software, Windows, Mac and Linux PCs can be turned into routers.
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.)