4. Internwtoerking devices

Internetworking devices which include Repeaters, Hubs, Routers, Switches, and Bridges. We started by defining each device followed by the various types and lastly how they work. Links were also provided for more information about each device. 

Like any type of technology, LANs have certain limitations. These limitations include the geographical distances that they cover, the number of nodes that can be connected, or the need to run more than one protocol. The devices within a network and the functions they support make a significant impact on the limitations of the network. Various types of hardware devices can be used to extend LAN functionality, each offering a specific function in exchange for added cost and complexity.

There are a variety of devices used to extend LANs, from a simple Network Interface Card (NIC) that allows you to connect to a network to a sophisticated router that can move information across the Internet. However, each device performs a specific function that, when combined with the functions of others, enables the LAN to transfer information from Point A to Point B.

•  Network Interface Cards (NICs)

The Network Interface Card (NIC) is a circuit board that is physically installed within an active network node, such as a computer, server, or printer. The NIC is an adapter that controls the exchange of information between the network and the user.  

Repeaters/Hubs

A repeater extends the length of a network cabling system by amplifying the signal and then re-transmitting it. Repeaters operate at Physical Layer 1. As a result, they do not look at the data at all. Any information coming into one port is simply repeated out all other ports.

A hub is another Layer 1 device that is typically used as a central point for connecting segments in a LAN. While passive hubs simply pass packets from one port to another, the signal may be regenerated in active hubs called multi-port repeaters. Hubs are becoming increasingly intelligent, enabling them to support network management and minimal path selection functions.

Bridges

As networks grow larger, they are often divided into smaller LANs to reduce traffic drain on the network. A bridge is a Data Link Layer 2 device that provides a connection between separate LAN segments. The bridge monitors packets as they move between segments, keeping track of the MAC addresses that are associated with various ports. As they gain more knowledge of the nodes connected to each network, they are better able to manage traffic flow.

Switches

Switches are becoming a more common way to connect networks together because they are simply faster and more intelligent than bridges. Advances in technology spawned a new generation of networking devices known as LAN switches, which included bridging as one of several functions. Switches have replaced bridges for two reasons: superior performance and lower price per port.

Routers

Routers were originally invented to solve some of the problems that weren't addressed by bridges. Like bridges, routers are used to segment a LAN in order to reduce excess broadcast traffic and latency. In addition, routers make internetworking possible by interconnecting both local and wide area networks.

The function of a router is to direct data along the most efficient and economical route to the destination device. Routers operate at Network Layer 3, which means they examine the logical network address (for example, 191.29.21.100) and not the physical hardware address (MAC). 

Routers are smarter than bridges because they know about routing protocols, different address schemes, different frame sizes and different data rates in order to make the best decision on which path to choose. The best path is determined by using routing tables and algorithms.