Explain various Networking Devices ? What is layer 3 switch ?

Some of the Common basic networking devices are:
* Gateway: device sitting at a network node for interfacing with another network that uses different protocols. Works on OSI layers 4 to 7.
* Router: a specialized network device that determines the next network point to which to forward a data packet toward its destination. Unlike a gateway, it cannot interface different protocols. Works on OSI layer 3.
* Bridge: a device that connects multiple network segments along the data link layer. Works on OSI layer 2.
* Switch: a device that allocates traffic from one network segment to certain lines (intended destination(s)) which connect the segment to another network segment. So unlike a hub a switch splits the network traffic and sends it to different destinations rather than to all systems on the network. Works on OSI layer 2.
* Hub: connects multiple Ethernet segments together making them act as a single segment. When using a hub, every attached device shares the same broadcast domain and the same collision domain. Therefore, only one computer connected to the hub is able to transmit at a time. Depending on the network topology, the hub provides a basic level 1 OSI model connection among the network objects (workstations, servers, etc). It provides bandwidth which is shared among all the objects, compared to switches, which provide a dedicated connection between individual nodes. Works on OSI layer 1.
* Repeater: device to amplify or regenerate digital signals received while setting them from one part of a network into another. Works on OSI layer 1.
Some hybrid network devices:
* Multilayer Switch: a switch which, in addition to switching on OSI layer 2, provides functionality at higher protocol layers.
* Protocol Converter: a hardware device that converts between two different types of transmissions, such as asynchronous and synchronous transmissions.
* Brouter: Combine router and bridge functionality and are therefore working on OSI layers 2 and 3.
* Digital media receiver: Connects a computer network to a home theatre
Hardware or software components that typically sit on the connection point of different networks, e.g. between an internal network and an external network:
* Proxy: computer network service which allows clients to make indirect network connections to other network services
* Firewall: a piece of hardware or software put on the network to prevent some communications forbidden by the network policy
Other hardware for establishing networks or dial-up connections:
* Multiplexer: device that combines several electrical signals into a single signal
* Network Card: a piece of computer hardware to allow the attached computer to communicate by network
* Modem: device that modulates an analog "carrier" signal (such as sound), to encode digital information, and that also demodulates such a carrier signal to decode the transmitted information, as a computer communicating with another computer over the telephone network
* ISDN terminal adapter (TA): a specialized gateway for ISDN
* Line Driver: a device to increase transmission distance by amplifying the signal. Base-band networks only.
Layer 3 Switch
Layer 3 switches work at layer 3(surprised???) and deals with IP's rather than with MAC address. I will try to find some more content on them and than write here. If you can find something than please post in comments.