to be like telephone switches, with whose technology they are currently converging and may some day replace, while small routers have become a typical household item.

An edge router is a router that connects clients to the Internet. A core router serves only to transmit data between other routers, e.g. inside the network of an Internet service provider.

Typically, a router is used to connect a minimum of two networks, but a special variety of router is the one-armed router, used to route packets in a virtual LAN environment. In the case of a one-armed router, the numerous attachments to different networks are all over the same physical link.

In mobile ad-hoc networks each host performs routing and forwarding on it's own, while in wired networks, there usually is only one router for a whole broadcast domain.

Recently, many routing functions have been added to LAN switches (a marketing term for high-speed bridges), making "Layer 2/3 Switches" which route traffic at almost wire speed.

Now routers are also being used as Internet gateways, mostly for small networks like the ones used in homes and small offices. This application is mainly where the Internet connection is an always-on broadband connection like cable modem or DSL. These are truly routers because they connect two networks together - the WAN and the LAN - and have a routing table. Many times these small routers support the RIP protocol, even though in a home application the routing function does not have much purpose since there are only two ways to go - the WAN and the LAN. Also, these routers usually supply DHCP, NAT, DMZ and Firewall services. Occasionally these routers can provide content filtering and VPN. Most times they are used in conjuction with either a cable modem or DSL modem, but that can also be a built-in function.