COMPUTER NETWORK – Two or more computers or peripheral devices that are connected together by a series of communication links. Networks exist to share resources such as computer hardware or data and to provide various means of communication.
- NODE : In networks, a processing location.
- A node can be a computer or some other device, such as a printer.
- Every node has a unique network address, sometimes called a Media Access Control (MAC) address
TECHNOLOGIES
- COMMON NETWORKING COMPONENTS
- Network Interface Card (NIC) – the expansion card placed inside the computer to communicate with other devices on a network
- Some NICs are built in. NICs can support wired or wireless connections.
- PC Card (PCMCIA) network adapters (wired and wireless)
- Bluetooth adapters
- Built-in wired or wireless adapters for items such as network storage hard drives
Devices designed to connect various segments of a network or networks together
- Hubs
- Switches
- Routers
Router
Cabling
- Twisted Pair
- Shielded Coaxial
- Fiber Optic
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| Cabling |
NETWORK ARCHITECTURES
- Networks can be broadly classified into groups by architecture
- Peer-to-Peer
- Client/Server
- Open Standard
- Proprietary
1-What is a Peer-To-Peer network?
Consist of hardware that is directly connected to each other for the purpose of sharing files and resources, such as two computers directly connected NIC to NIC.
- PEER-TO-PEER File Sharing Networks
- Peer-to-peer file sharing networks were made popular in the recent years by file sharing networks like Kazaa, Napster, Morpheus, and others.
- How is this different from normal file downloading?
- Peer-to-peer file sharing networks have a high distribution of viruses, Trojan programs, and other malware.
- If a user within a business network environment allows a peer-to-peer connection to their computer, it may subvert security and lead to a network incident.
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| Peer-To-Peer Network |
2-Client/Server networks
Typically rely on a number of client workstations that connect to a more powerful computer known as a server that is setup for the specific purpose of sharing resources.
3-What are open standard networks vs. proprietary networks?
- Open standard networks:
- Allow the system to be connected to other devices and software from a variety of manufacturers. This hardware and software configuration conforms to industry standards.
- Proprietary networks:
- Use hardware, software, and network protocols that are not industry standards. These can be difficult to integrate with other networks.
BROADBAND TECHNOLOGIES
Broadband - refers to the ability for pipelines to carry multiple streams of data at one time.
- ISDN – 128 Kbps – 1.47 Mbps
- xDSL – 1 Mbps downstream
- T-1 (DS1) – 1.544 Mbps
- Cable – 2 to 4 Mbps
- T-3 (DS3) – 43 Mbps
Kbps = Kilobits per second
Mbps = Megabits per second
Gbps = Gigabits per second
OC = Optical Carrier (Fiber Optic Networks)
Fiber Optics
- OC-1 – 51.85 Mbps
- OC-3 – 155.52 Mbps
- OC-12 – 622.08 Mbps
- OC-24 – 1.244 Gbps
- OC-48 – 2.488 Gbps
- OC-192 – 9.952 Gbps
- OC-255 – 13.21 Gbps
LOCAL AREA NETWORK (LAN) :
A local area network is defined as a computer network that spans a relatively small area.
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| Local Area Network |
Wide Area Network (WAN)
- A computer network that spans a relatively large geographical area.
- A WAN is nothing more than two or more LANs connected together.
- WANs are usually connected using some form of public media such as the Internet or commercial telephone equipment.
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| Wide Area Network (WAN) |
What is the largest WAN in the world?
The largest WAN is the Internet itself…
How Networks Work?
Step One: Hardware Infrastructure
Step Two:
- How does data get from one device (NIC) to another?
- How does one NIC recognize another one?
Network Interface Card
MAC ADDRESS
- is a 48-bit binary number.
- is represented in hexadecimal format so that it can be easily read.
- is represented as six groups of two hex digits, as in this example: 00-0D-56-EB-D0-9E
- Each MAC Address can be split in half when read.
- The first half is called the Organizationally Unique Identifier (OUI), and is unique to a given manufacturer.
- The second half of the address is unique to a specific card. ( 00-0D-56 / EB-D0-9E )
- You can easily discover the MAC Address of your network card from a command line by typing:
- In Windows:
- ipconfig /all
- In Unix/Linux:
- ifconfig –a
- To look up MAC address vendor codes, go to
- http://standards.ieee.org/regauth/oui/oui.txt
- or enter “mac address vendor codes” in
- Google.
Network Information arp -a
- To obtain information about your network:
- Type: Start,
- Run
- CMD
- and then type “arp –a”
