Default gateway
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In computer networking, a gateway is a node (a router) on a TCP/IP network that serves as an access point to another network. A default gateway is the node on the computer network that the network software uses when an IP address does not match any other routes in the routing table.
In home computing configurations, an ISP often provides a physical device which both connects local hardware to the Internet and serves as a gateway. Such devices include DSL modems and cable modems.
In organizational systems a gateway is a node that routes the traffic from a workstation to another network segment. The default gateway commonly connects the internal networks and the outside network (Internet). In such a situation, the gateway node could also act as a proxy server and a firewall. The gateway is also associated with both a router, which uses headers and forwarding tables to determine where packets are sent, and a switch, which provides the actual path for the packet in and out of the gateway.
In other words, a default gateway provides an entry point and an exit point in a network. Contents [hide] * 1 Example1 * 2 Example2 * 3 See also * 4 External links |
[edit] Example1
An office network consists of six hosts and a router is given as:
Hosts addresses: * 192.168.4.3 * 192.168.4.4 * 192.168.4.5 * 192.168.4.6 * 192.168.4.7 * 192.168.4.8
Router (this side) address: * 192.168.4.1
The network has a subnet mask of: * 255.255.255.0 (/24 in CIDR notation)
Thus the usable network ranges from addresses 192.168.4.1 to 192.168.4.254. (TCP/IP defines the addresses 192.168.4.0 and 192.168.4.255 for special functions.)
The office's hosts will send packets addressed to IPs within this range directly, by resolving the destination IP address into a MAC address through an ARP sequence