NETWORKING
Networks are everywhere—or so it seems. You can hardly do anything with data that does not involve a network.
Like the human networks that we are all part of, computer networks let us share information and resources. In business,the reliance on networks is even more pervasive than in homes or schools.
Networks help individuals and businesses alike save money, but they also help create income. Without a doubt, networking within the home will catch on overthe next few years as it has in business. Soon, nearly all individuals in even moderately developed nations will have networked components throughout their homes. Those that don’t will be netologically disadvantaged because they will not be able to learn or to function at the same level as those who are networked.
In this chapter, you’ll begin by relating networks to situations and concepts you already know. Once you have a basic understanding of what networks areand what they can do, it helps if you can actually begin working with them. Infact, it is so helpful to learn the ropes of networking through hands-on guided practice that that’s what is planned for you here. You will play the role of an employee in a fictional company, and you’ll have to learn on the job.
Human Networks
In its broadest sense, a network consists of two or more entities, or objects,sharing resources and information. Although this book is about computer networks, there are networks that don’t involve computers, and those networks are everywhere. You have grown accustomed to working with
them, possibly without even knowing it.
It may not matter to you that, in a basic sense, sharing (giving or getting)is a fundamental aspect of networking. You just know that you do it.
Family Network Most people belong to a family network in which related people share their resources and information. This sharing is bi-directional because even the youngest family members share information of some sort. As the family grows, so does the network.
Peer Network
Outside the family, there is a community that offers a wider array of resources than the typical family can provide.
Contact Network
Anyone who has looked for a job knows that one of the best ways to find a job is to network. That is, create a list of friends and associates who will help you find the perfect job. The more people you meet and get to know, the
better your chances of obtaining work.
Maintaining the Network
Purchasing similar equipment for use on the network meant that network maintenance costs were reduced because there were fewer dissimilar
components. Maintenance workers no longer had to attend numerous
training sessions on many different components, which meant they could
spend more time maintaining the actual components.
Backing Up Data
Along those same lines, a network minimizes the time spent backing up (saving extra copies, called backups) of necessary files. In the event of a hardware or software failure that causes information or applications to be lost, vital information and necessary applications can be restored if sufficient backups exist.
Internet Service
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The technologies used to connect to the internet are different than those used for connecting devices on local area network. Digital subscriber lines (DSL), cable modems, and fiber provide fixed broadband internet service, while WiMax and LTE additionally support mobile connectivity. In geographic areas where these high-speed options are unavailable, subscribers are forced to use older cellular services, satellite, or even dial-up internet instead.
Networking Glossary
- Connection: In networking, a connection refers to pieces of related information that are transfered through a network. This generally infers that a connection is built before the data transfer (by following the procedures laid out in a protocol) and then is deconstructed at the at the end of the data transfer.
- Packet: A packet is, generally speaking, the most basic unit that is transfered over a network. When communicating over a network, packets are the envelopes that carry your data (in pieces) from one end point to the other.
Packets have a header portion that contains information about the packet including the source and destination, timestamps, network hops, etc. The main portion of a packet contains the actual data being transfered. It is sometimes called the body or the payload.
- Network Interface: A network interface can refer to any kind of software interface to networking hardware. For instance, if you have two network cards in your computer, you can control and configure each network interface associated with them individually.
A network interface may be associated with a physical device, or it may be a representation of a virtual interface. The “loopback” device, which is a virtual interface to the local machine, is an example of this.
- LAN: LAN stands for “local area network”. It refers to a network or a portion of a network that is not publicly accessible to the greater internet. A home or office network is an example of a LAN.
- WAN: WAN stands for “wide area network”. It means a network that is much more extensive than a LAN. While WAN is the relevant term to use to describe large, dispersed networks in general, it is usually meant to mean the internet, as a whole.
If an interface is said to be connected to the WAN, it is generally assumed that it is reachable through the internet.
- Protocol: A protocol is a set of rules and standards that basically define a language that devices can use to communicate. There are a great number of protocols in use extensively in networking, and they are often implemented in different layers.
Some low level protocols are TCP, UDP, IP, and ICMP. Some familiar examples of application layer protocols, built on these lower protocols, are HTTP (for accessing web content), SSH, TLS/SSL, and FTP.
- Port: A port is an address on a single machine that can be tied to a specific piece of software. It is not a physical interface or location, but it allows your server to be able to communicate using more than one application.
- Firewall: A firewall is a program that decides whether traffic coming into a server or going out should be allowed. A firewall usually works by creating rules for which type of traffic is acceptable on which ports. Generally, firewalls block ports that are not used by a specific application on a server.
- NAT: NAT stands for network address translation. It is a way to translate requests that are incoming into a routing server to the relevant devices or servers that it knows about in the LAN. This is usually implemented in physical LANs as a way to route requests through one IP address to the necessary backend servers.
- VPN: VPN stands for virtual private network. It is a means of connecting separate LANs through the internet, while maintaining privacy. This is used as a means of connecting remote systems as if they were on a local network, often for security reasons.