Network Structures

To understand a minimal network structure must understand that basically there are two basic models of networks, peer network and client / server network.

Peer Network
The peer network (Figure 1) works in a basic way, all PCs are connected to a hub or a switch (both will be discussed later on) with their network cards configured in the same range of IP addresses. Those systems possess shared resources (folders, printers, scanners, etc. ...). This network model is suitable for networks of few users and that does not require network services more accurate.

networks
Figure 1 - model of peer network

Client / Server Network
The model of Client / Server network (Figure 2) is a way of organizing a network of computer servers that will have the responsibility to provide some type of service in the network. For example, in a medium sized company (up to 100 computers) could have a firewall to control Internet links, navigation, and to analyze the network, another server for e-mail company, a server to serve files and printers and so on.

networks
Figure 2 - Model of client / server network

 

Some definitions of computer networks
To get a better understanding in our day to day, the sequence will be explaining about elements, terms, applications and processes in a computer network.

Networking Hardware
In this section we discuss some physical elements of a network (there are many, what we are addressing here is just the basics for a layman).

Server
Hardware or computer system that provides services to a network of computers. Services may be numerous, some basic examples:
             - Routing networks;
             - Firewall;
             - Control network usage and navigation control;
             - E-mails;
             - FTP;
             - Sites;
             - Messenger (instant messaging);
             - Fileserver - Server for archives;
             - SoftServe - server specific software (eg ERP).

HUB / SWITCH
The hub acts as a signal extender, as an extension of electrical outlets. He divides the signal to all computers connected to it. If he receives an amount of data, it sends all the data for all connections at the same time.
The switch works a little different, but within the same principles, the main difference is that in the case of Switch, it separates the data by sending an organized data for active connections, and one at a time. Noting that although to have a connection at a time, the velocity relative to the hub is greater because if the hub is a great loss of data, because there are a lot of traffic, causing the computer needs to resend the lost data during the path.

Terms / Applications

IP

The IP address, in a general way can be considered as a set of numbers representing the location of a particular piece of equipment (usually computers) in a private or public network.

MAC (Media Access Control): It is a physical address, present in all the network adapters, it is composed of 6 (six) fields, with two (2) alphanumeric characters each. For code example, is a MAC address: 0F-T7-66-AS-FG-70, and the first three fields (0F-T7-66), linked to the manufacturer, ie the first three fields, we can define what the manufacturer board, and the last three (AS-FG-70), a serial number of manufacture, making it impossible for there are more than one network card with the same physical address. This information is of vital importance to identify the DHCP computer on your network.

DHCP

DHCP is a service that provides information for network computers. This service contains the information the computer needs to operate within a network, ie, define who is who in a network. Through DHCP, your computer gets an IP address, which the gateway through which traffic will pass, DNS servers for name resolution and netmask.

Operation Dhcp
The computer, when turned on and the network started, sends a signal called Broadcast, this signal is sent to all network elements. The DHCP server sees this signal, identifies the network card (MAC) and responds, then the computer says it needs the information such as IP, netmask, gateway, nameservers. The DHCP server sends this information to the MAC address you request, the computer receives data, applies the network card, freeing up the browsing and the internal network.

DNS

DNS is a service that makes the translation of a name (www.msitec.com.br) in an IP address (200.xxx). As noted earlier, the IP address used to computers / servers "see" each other within a network, but how would not be easy to memorize so many IP addresses, then were set up DNS servers.

Operation Dns
It works like typing the address of a site in your browser, the browser uses the settings of your network and sends the information to your DNS server, pre-defined by DHCP and Gateway. Your DNS server checks if the name exists in the database, there is not, it forwards the data to a larger server, a server named Bastion Host (which are a total of eight servers on the planet) that contains all the information names of the world. If he gets the IP information, it returns this information IP pra origin, and then the browser search the site. This procedure happens in a very fast (less than a second on average).