Introduction to Computers Networking Hardware

Network Interfaces The first piece of hardware we’re going to talk about is the network interface card (NIC). Every computer on your network will have a NIC. This is the device that will take the binary data from the computer and turn it into signals the connection media can carry Motherboards will often have an integrated NIC, but we can replace that for one with faster connections or a different interface The interface needed will depend entirely on the connection media Every device on the network will need a network interface of some kind in order to translate the data, hosts as well as networking devices Every NIC will have a built-in physical address called a MAC address that uniquely identifies it

Connection Media - Bounded Media Connection media is the physical connective material between devices on a network We can separate media into two main categories - bounded and unbounded Bounded media means that the media is physically separated from the outside world Unbounded media means that the media transmits through the air A good rule of thumb is that bounded media is in a cable, unbounded is not For bounded media, we have two main types - Copper wiring - copper wiring moves signals through the network via electric impulses. There are two main forms of copper wiring used for networking - twisted pairs ending in an RJ45 connector (commonly called ethernet cables) and coaxial cable Fiber Optic Cabling - fiber optic cables move signals through the network via light pulses. This tends to be much faster than copper cabling

Connection Media - Unbounded Media There are two types of unbounded network media, though one is used much more than the other Radio waves - we can use wifi or bluetooth to propagate media throughout the network with radio waves. Wifi is longer range, and bandwidth is higher

Central Connecting Point While it is possible for devices to be directly connected to each other, we typically want to connect to multiple devices, and the easiest way to facilitate that is by using a central connecting point The abilities of a central connecting point can vary drastically, and will dictate how we can use the network

Hubs The first is called a hub. Hubs are the most basic type of central connecting device They offer very little functionality beyond connecting devices together, and do very little to manage the data flow Hubs store no information, so when a computer in the network sends data to the hub, the best it can do is repeat the message to the other ports on the hub. For this reason a hub is sometimes called a repeater Each computer connected to the hub then looks at the information. If it's addressed to it, then it processes it. If it's not, then the computer discards it This greatly limits the scalability of our network. The larger the network, the more message will be on the pipeline, and the more collisions there will be What physical topology would this be? What logical topology?

Switch Switches look very similar to hubs. However, they function very differently. Unlike hubs, switches know which host is connected to each port When information is sent to the hub from a computer, the switch looks at the data, reads the MAC address, and uses it to select a port to send the message down Switches allow networks to be much more scalable. Messages are only sent to the host that need to receive them, so there is no chance for collision. Switches eliminate the issues that hubs create

Duplex Mode Networks can operate in two different modes - half duplex and full duplex Half duplex mode devices can either send data or receive data but not both at the same time This is the mode that hub-based networks use Like its name suggests, half duplex mode cuts network bandwidth in half Full duplex mode devices can send and receive data both at the same time This is the mode that switch-based networks use This allows us to use the full bandwidth of our connections

Routers Hubs and switches connect hosts together into a network. Routers connect switches and hubs together to connect networks Unlike a switch, routers use the IP address of the data packet to figure out where to send the packet. We’ll see why later, but in general it is because IP addresses make it easier to define a range of hosts (like a network), and MAC addresses Routers will connect to switches and hubs in order to send data into networks, but they will also be connected to other routers. Routers will construct a routing table that will let it know what router to send a specific IP address to in order to get it closer to its destination network This is essentially how the Internet works. Multiple routers connect multiple networks together allowing communication among all the connected networks

Routers and Switches Routers and switches tend to work together. If the switch sees an unfamiliar MAC address it will be sent to the router, who will use the IP address to figure out where to send it When a router sees an IP address for a host on the switch’s network it will send the message to the switch which will use the message’s target MAC address to send the message to the specific computer that is the target

Bridges The final network connectivity device we’re looking at is a bridge A bridge combines two or more switches together to make a larger network Since it connects the switches into one big network, there is no longer a benefit to using IP addresses to determine ports. As such bridges use MAC addresses to decide what port to send messages on