Homework

Homework of:

Computer networks.

Present by:

Alejandra Moreno Gonzales

Leiry Daniela Beitia Horta

Daniela Marin Marin

Melissa Mejia Gomez

Instructor:

Andrés Mauricio Clavijo.

Grade:

10

Juan de Dios Girón

Educational Institution.

La Unión Valle.

4-november-2015

Content:

1. Computer network2. Properties3. Network packet4. Network topology5. Network links 6. Wired technology6.1 coaxial cable6.2 ITU – TG6.3 Twisted pair wire6.4 An optical fiber7 Wireless technology

7.1 Terrestrial microwave

7.2 Communications satellites

7.3 Cellular and pcs systems

7.4 Radio and spread spectrum technology

7.5 Free space optical communication

8. Exotic technologies

9. IP

10. Network nodes

11. Repeaters and hubs

12. Bridges

13. Routers

14. Firewalls

15. Network structure

16. Common layouts

16.1. A bus network

16.2. A star network

16.3. A ring network

16.4. A mesh network

16.5. A fully connected network

17. Basic components of the network

18. Functional relationship

19. By technology

19.1. Point to point network

19.2. Broadcasting network

19.3. Multipoint network

20. PAN network

21. WPAN network

22. LAN network

23. WLAN network

24. CAN network

25. MAN network

26. WAN network

27. SAN network

28. VLAN network

Introduction:

The next job is to publicize the computer networks and everything about them. Information you need to know to be part of the mode of institution.

Computer networks.

A computer network or data network is a telecommunications network which allows computers to exchange data. In computer networks, networked computing devices exchange data with each other along network links (data connections). The connections between nodes are established using either cable media or wireless media. Network computer devices that originate, route and terminate the data are called network nodes. Nodes can include hosts such as personal computers, phones, servers as well as networking hardware.

Computer networks differ in the transmission media used to carry their signals, the communications protocols to organize network traffic, the network's size, topology and organizational intent. In most cases, communications protocols are layered on (ie work using) other more specific or more general communications protocols, except for the physical layer that directly deals with the transmission media.

properties

Computer networking may be considered a branch of electrical engineering, telecommunications, computer science, information technology or computer engineering, since it relies upon the theoretical and practical application of the related disciplines.

A computer network facilitates interpersonal communications allowing people to communicate efficiently and easily via email, instant messaging, chat rooms, telephone, video telephone calls, and video conferencing. Providing access to information on shared storage devices is an important feature of many networks. A network allows sharing of files, data, and other types of information giving authorized users the ability to access information stored on other computers on the network. A network allows sharing of network and computing resources. Users may access and use resources provided by devices on the network, such as printing a document on a shared network printer. Distributed computing uses computing resources across a network to accomplish tasks. A computer network may be used by computer crackers to deploy computer viruses or computer worms on devices connected to the network, or to prevent these devices from accessing the network via a denial of service attack.

Network packet.

Computer communication links that do not support packets, such as traditional point-to-point telecommunication links, simply transmit data as a bit stream. However, most information in computer networks is carried in packets. A network packet is a formatted

unit of data (a list of bits or bytes, usually a few tens of bytes to a few kilobytes long) carried by a packet-switched network.

In packet networks, the data is formatted into packets that are sent through the network to their destination. Once the packets arrive they are reassembled into their original message. With packets, the bandwidth of the transmission medium can be better shared among users than if the network were circuit switched. When one user is not sending packets, the link can be filled with packets from others users, and so the cost can be shared, with relatively little interference, provided the link isn't overused. Packets consist of two kinds of data: control information and user data (also known as payload). The control information provides data the network needs to deliver the user data, for example: source and destination network addresses, error detection codes, and sequencing information. Typically, control information is found in packet headers and trailers, with payload data in between. Often the route a packet needs to take through a network is not immediately available. In that case the packet is queued and waits until a link is free.

Network topology.

The physical layout of a network is usually less important than the topology that connects network nodes. Most diagrams that describe a physical network are therefore topological, rather than geographic. The symbols on these diagrams usually denote network links and network nodes.

Network links.

The transmission media (often referred to in the literature as the physical media) used to link devices to form a computer network include electrical cable (Ethernet, Home PNA, power line communication, G.hn), optical fiber (fiber-optic communication), and radio waves (wireless networking). In the OSI model, these are defined at layers 1 and 2 — the physical layer and the data link layer.

A widely adopted family of transmission media used in local area network (LAN) technology is collectively known as Ethernet. The media and protocol standards that enable communication between networked devices over Ethernet are defined by IEEE 802.3. Ethernet transmits data over both copper and fiber cables. Wireless LAN standards (eg those defined by IEEE 802.11) use radio waves, or others use infrared signals as a transmission medium. Power line communication uses a building's power cabling to transmit data.

Wired technologies.

Coaxial cable: is widely used for cable television systems, office buildings, and other work-sites for local area networks. The cables consist of copper or aluminum wire surrounded by an insulating layer (typically a flexible material with a high dielectric constant), which itself is surrounded by a conductive layer.

ITU-TG.hn technology uses existing home wiring (coaxial cable, phone lines and power lines) to create a high-speed (up to 1 Gigabit/s) local area network.

Twisted pair wire: is the most widely used medium for all telecommunication. Twisted-pair cabling consist of copper wires that are twisted into pairs.

An optical fiber: is a glass fiber. It carries pulses of light that represent data. Some advantages of optical fibers over metal wires are very low transmission loss and immunity from electrical interference.

Wireless technologies.

Terrestrial microwave – Terrestrial microwave communication uses Earth-based transmitters and receivers resembling satellite dishes.

Communications satellites – Satellites communicate via microwave radio waves, which are not deflected by the Earth's atmosphere. The satellites are stationed in space, typically in geosynchronous orbit 35,400 km (22,000 mi) above the equator.

Cellular and PCS systems use several radio communications technologies. Each area has a low-power transmitter or radio relay antenna device to relay calls from one area to the next area.

Radio and spread spectrum technologies – Wireless local area networks use a high-frequency radio technology similar to digital cellular and a low-frequency radio technology.

Free-space optical communication uses visible or invisible light for communications.

Exotic technologies.

There have been various attempts at transporting data over exotic media:

IP over Avian Carriers was a humorous April fool's Request for Comments, issued as RFC 1149. It was implemented in real life in 2001.

Extending the Internet to interplanetary dimensions via radio waves.

Both cases have a large round-trip delay time, which gives slow two-way communication, but doesn't prevent sending large amounts of information.

Network nodes.

Apart from any physical transmission medium there may be, networks comprise additional basic system building blocks, such as network interface controller (NICs), repeaters, hubs, bridges, switches, routers, modems, and firewalls.

Network interfaces.

A network interface controller (NIC) is computer hardware that provides a computer with the ability to access the transmission media, and has the ability to process low-level network information. For example, the NIC may have a connector for accepting a cable, or an aerial for wireless transmission and reception, and the associated circuitry.

The NIC responds to traffic addressed to a network address for either the NIC or the computer as a whole.

In Ethernet networks, each network interface controller has a unique Media Access Control (MAC) address—usually stored in the controller's permanent memory. To avoid address conflicts between network devices, the Institute of Electrical and Electronics Engineers (IEEE) maintains and administers MAC address uniqueness. The size of an Ethernet MAC address is six octets.

The three most significant octets are reserved to identify NIC manufacturers. These manufacturers, using only their assigned prefixes, uniquely assign the three least-significant octets of every Ethernet interface they produce.

Repeaters and hubs.

A repeater is an electronic device that receives a network signal, cleans it of unnecessary noise and regenerates it. The signal is retransmitted at a higher power level, or to the other side of an obstruction, so that the signal can cover longer distances without degradation. In most twisted pair Ethernet configurations, repeaters are required for cable that runs longer than 100 meters. With fiber optics, repeaters can be tens or even hundreds of kilometers apart.

A repeater with multiple ports is known as a hub. Repeaters work on the physical layer of the OSI model. Repeaters require a small amount of time to regenerate the signal. This can cause a propagation delay that affects network performance. As a result, many network architectures limit the number of repeaters that can be used in a row, eg, the Ethernet 5-4-3 rule.

Hubs have been mostly obsoleted by modern switches; but repeaters are used for long distance links, notably undersea cabling.

Bridges.

A network bridge connects and filters traffic between two network segments at the data link layer (layer 2) of the OSI model to form a single network. This breaks the network's collision domain but maintains a unified broadcast domain. Network segmentation breaks down a large, congested network into an aggregation of smaller, more efficient networks.

Bridges come in three basic types:

Local bridges: Directly connect LANs. Remote bridges: Can be used to create a wide area network (WAN) link between

LANs. Wireless bridges: Can be used to join LANs or connect remote devices to LANs.

Routers.

A router is an internetworking device that forwards packets between networks by processing the routing information included in the packet or datagram (Internet protocol information from layer 3). The routing information is often processed in conjunction with

the routing table (or forwarding table). A router uses its routing table to determine where to forward packets.

Firewalls.

A firewall is a network device for controlling network security and access rules. Firewalls are typically configured to reject access requests from unrecognized sources while allowing actions from recognized ones. The vital role firewalls play in network security grows in parallel with the constant increase in cyber-attacks.

Network structure.

Network topology is the layout or organizational hierarchy of interconnected nodes of a computer network. Different network topologies can affect throughput, but reliability is often more critical. With many technologies, such as bus networks, a single failure can cause the network to fail entirely. In general, the more interconnections there are, the more robust the network is; but the more expensive it is to install.

Common layouts.

Common layouts are:

A bus network: all nodes are connected to a common medium along this medium. This was the layout used in the original Ethernet, called 10BASE5 and 10BASE2.

A star network: all nodes are connected to a special central node. This is the typical layout found in a Wireless LAN, where each wireless client connects to the central Wireless access point.

A ring network: each node is connected to its left and right neighbor node, such that all nodes are connected and that each node can reach each other node by traversing nodes left- or rightwards.

A mesh network: each node is connected to an arbitrary number of neighbors in such a way that there is at least one traversal from any node to any other.

A fully connected network: each node is connected to every other node in the network.

A tree network: nodes are arranged hierarchically.

Basic components of the networks:

Hardware, software and protocols: to form a network elements are required. The physical elements are classified into two groups: end-user devices (hosts) and network devices. The end-user devices include computers, printers, scanners, and other elements that provide services directly to the user and the latter are those that connect to end-user devices, allowing intercommunication.

The purpose of a network is to interconnect the hardware components of a network, and therefore mainly individual computers, also called hosts, teams that make services on the network, servers, using the wiring or wireless technology supported by the electronic network and linked by cable or radio frequency. In all cases the network card can be considered the main item; it is part of a computer, a switch, a printer, etc. and be it technology (Ethernet, Wi-Fi, Bluetooth, etc.)

functional relationship

• Client-server architecture is that basically consists of a client making requests to another program (the server) that gives answer.

• Peer-to-peer network or peer computer network is one in which all or some aspects work without fixed customers or servers, but a series of nodes that behave as equal.

By technology

• point to point network is one in which there is a multitude of connections between individual pairs of machines. This type of network requires, in some cases, intermediate systems establish routes for data packets can be transmitted. The usual electronic means for interconnection is the switch or switch.

• Broadcasting Network (broadcast) is characterized by transmitting data over a single communication channel shared by all machines on the network. In this case, the packet sent is received by all machines on the network but only the recipient can process. The teams joined by a hub, forming networks of this kind.

• multipoint network, has a line or media whose use is shared by all terminals in the network. Information flows bidirectional. The terminals can be geographically separated.

PAN network (personal area network)

Personal area network (PAN) is a computer network used for communication between devices in computer information technologies and different about a person. BREAD represents the concept of people-centered networks, and that allow these people to communicate with their personal devices (eg, PDAs, electronic boards of navigation, PDAs, laptops) so as to enable a wireless connection to the world external. Some examples of devices that are used in a PAN are personal computers, printers, fax machines, phones, PDAs, scanners and video game consoles.

The PAN may include wired and wireless devices.

The reach of a PAN typically extends to 10 meters.

A wired PAN is usually constructed with USB and Fire wire connections while technologies such as Bluetooth and infrared communication typically form a wireless PAN.

Keywords: personal area network (PAN), PAN personal area networks, identifying common threats to wireless security, bread personal area network, computer network bread, bread scope of the network, which is the scope of a pan network.

WPAN network

Wireless Personal Area Network (WPAN), Wireless Personal Area Network or Wireless Personal Area Network is a computer network for communication between different devices (computers, internet access points, cell phones, PDAs, audio devices, printers) close to the access point.

These networks are typically a few meters and for personal use.

The basis of the concept of network for personal space came from ideas that emerged in 1995 from the Massachusetts Institute of Technology (MIT) come to use electrical signals or electrical impulses from the human body, so we can communicate the same with attached devices. This was accepted first by IBM Research Labs and then had many variations developed by the various institutions and research companies. PAN different solutions include:

• Project Oxygen (MIT);

• Pico-radius;

• Infrared Data Association (IrDA);

• Bluetooth;

The concept of Bluetooth, originally developed to replace cables, is being accepted worldwide, and some of these ideas are incorporated into the IEEE 802.15 standard related to the NAPs.

LAN network.It is a group of computers that belong to the same organization and are linked within a small geographic area through a network, usually with the same technology (the most he used to be Ethernet).

A local area network is a network in its simplest form. The speed of data transfer in a local area network can reach 10 Mbps (for example, an Ethernet network) and 1 Gbps (for example, FDDI, or Gigabit Ethernet). A local area network may contain 100 or even 1000, users.

By extending the definition of a LAN to the services provided, you can define two different operating modes:

• In a network "peer to peer" (abbreviated P2P) communication takes place from one computer to another without a central computer and each team has the same function.

• In an environment "client / server", a central computer provides network services to users.

WLAN network

A Wireless LAN, also known as WLAN (wireless local area network of), is a flexible wireless communication, widely used as an alternative to wired LANs, or as an extension thereof. Using radio frequency technology that allows greater mobility to users by minimizing wired connections. These networks are gaining importance in many fields, such as warehouses or manufacturing, where the information in real time to a central terminal is transmitted. They are also very popular in nightclubs to share Internet access among multiple computers.

Wi-Fi access point.

Performance:

Radio waves are used to carry information from one point to another without physical media guide. Speaking of radio waves we usually refer to radio carriers, on which the information is going, and which function to bring energy to a remote receiver. Data to be transmitted are superimposed on the radio carrier and thus can be accurately extracted at the receiver end.

This process is called modulation of the carrier by the information being transmitted. If the waves are transmitted at different radio frequencies, several carriers can exist in the same time and space without interfering with each other. To extract the data receiver is at a given frequency, carrier frequency, ignoring the rest. In a typical configuration of LAN (wired) access points (transceiver) connect the wired network from a fixed location using standard cabling. The access point receives the information, stores and transmits between the WLAN and the wired LAN. A single access point can support a small group of users and can function in a range of at least thirty meters up to several hundred. The access point (or antenna connected to the access point) is normally placed in high but could be placed anywhere in the desired radio coverage is obtained. The end user accesses the network via WLAN adapters. They provide an interface between the operating system client network (NOS: Network Operating System) and waves through an antenna.

The nature of the wireless connection is transparent to the client layer.

CAN network:

A campus network (CAN) is a computer network that connects LANs via a limited geographical area such as a campus universitario, or a military base. It can be considered as a metropolitan area network that specifically applies to a university environment. Therefore, a campus network is larger than a local area network but smaller than a wide area network.

In a CAN, university buildings are connected using the same type of computer and network technologies that would be used on a LAN. Moreover, all components, including switches, routers, wiring, and others belong to the same organization.

A CAN is a geographically dispersed collection of LANs within a campus (university, government offices, or marquise’s industries) belonging to the same entity in a defined area in kilometers.

A CAN commonly used technologies such as FDDI and Gigabit Ethernet connectivity through media such as fiber optics and spread spectrum.

MAN network.

A metropolitan area network (MAN, English acronym Metropolitan Area Network) is a network of high-speed (broadband) that covers a large geographic area, providing ability to integrate multiple services by transmitting data, voice and Video on transmission media such as fiber optic and twisted pair (MAN LOOP), the copper pair technology is positioned as the world's largest network an excellent alternative to the creation of metropolitan networks, low latency (between 1 and 50 ms), high stability and lack of radio interference LOOP MAN networks offer speeds of 10 Mbit / s or 20 Mbit / s over copper pairs and 100 Mbit / s, 1 Gbit / s and 10 Gbit / s by optical fiber.

Networks MAN loop Bonding technologies are based on so that the links are formed by multiple pairs of copper in order to provide the required bandwidth.

Furthermore, this technology guarantees 99.999 SLASH'S, thanks to the links are formed by multiple pairs of copper and is materially impossible for 4, 8 or 16 threads simultaneously they break down.

The metropolitan area networks have many and varied applications, the main ones:

• Deployment of VoIP (Voice over IP), in the metropolitan area, allowing remove "obsolete" traditional analog lines or ISDN telephony, eliminating the current expenditure of these lines.

• interconnection of local area networks (LAN).

• Deployment of Wi-Fi Zones without wireless backhaul (Femtocell) releasing all wireless channels to access, in practice this is more than 60% improvement in connecting wireless users.

• Interconnection computer to computer.

• municipal video surveillance systems.

• Transmission CAD / CAM.

• Gateways for wide area networks (WAN).

They also allow the transmission of voice traffic, data and video with high latency guarantees, reasons why the installation of a metropolitan area network at the corporate level, for corporations with multiple offices in the capital area is necessary.

WAN network:

A broad network, or WAN area (Wide Area Network), is a computer network that spans multiple physical locations, providing service to a region, a country, even several continents. It is any network that connects multiple local networks, LAN calls, so that its members are not all in the same physical location. Many WANs are built by organizations or companies for private use, others are installed by Internet service providers (ISP) to provide connection to its customers.

Today, the Internet provides high-speed connections, so that a high percentage of WAN networks are based in that environment, reducing the need for private networks WAN while virtual private networks using encryption and other techniques to generate a dedicated communications network on the Internet, continuously increase.

 Characteristics:

• It has engaged in the execution of user programs (hosts) machines.

• A subnet, which connect multiple hosts.

• Division between transmission lines and switching elements (routers).

• A system of interconnection of geographically dispersed computers, which may be even on different continents. The connection system for these networks to public networks typically involves transmission of data.

WAN Types

Several types of WAN, and three of them are grouped under the classification of switched network (physical, switching consists in changing the destiny of a signal or an electric current)

Circuit for communication, this type of WAN requires that a call is made and the connection only when each user has made a direct link.

By message:

Its switches are usually computers that meet the task to accept traffic from each terminal that is connected to them. These teams evaluate the address listed in the header of the message and can store it for later use. It is worth mentioning that you can delete, redirect messages and respond automatically.

Packet:

Every message sent by users is fractionated and transformed into a number of small parts called packets, which are reassembled once they arrive at the destination computer to reconstruct the initial data. These packets move through the network independently, and this has a positive effect on traffic and facilitates error correction, because in case of failure only affected parties should forward.

SAN network:

A storage area network, English Storage Area Network (SAN) is a complete storage network. It is a complete architecture that groups together the following elements:

• A network of high-speed Fiber Channel or iSCSI.

• A dedicated interconnection equipment (switches, bridges, etc.).

• Network storage elements (hard drives).

A SAN is a network dedicated to storage that is connected to the communication networks of a company. In addition to traditional network interfaces, computers with access to the SAN have a specific network interface that connects to the SAN.

SAN performance is directly related to the type of network used. In the case of a Fiber Channel network, the bandwidth is approximately 100 megabytes / second (1,000 megabits / second) and can be extended by increasing the amount of access connections.

SAN capacity can be extended almost limitlessly and can reach hundreds and even thousands of terabytes.

A SAN can share data among multiple computers on the network without affecting performance because SAN traffic is completely separate from user traffic. Are application

servers that act as an interface between the data network (usually fiber channel) and the user network (at general Ethernet).

Moreover, a SAN is much more expensive than a network-attached storage (NAS) because the first is a complete architecture that uses technology that is still very expensive. Normally, when a company estimates the total cost of ownership (TCO) compared to the cost per byte, the cost can be justified more easily.

It is also a designed to connect servers, matrices (arrays) disks and network support libraries. It is mainly based on fiber channel technology and more recently in iSCSI. Its function is to connect quickly, securely and reliably the different elements that comprise manner.

SAN uses different access protocols such as Fiber Channel and Gigabit Ethernet. On the opposite side is the Network-Attached Storage (NAS), where applications make data requests to the file systems remotely using Server Message Block protocols (CIFS) Network File System (NFS).

Esquema. DAS vs. NAS vs. SAN.

VLAN network:

A VLAN stands for Virtual LAN (virtual local area network) is a method for creating independent logical networks within a single network física.1 Several VLANs can coexist on a single physical switch or on a single physical network. They are useful to reduce the size of the broadcast domain and help in network administration by separating logical segments of a local area network (departments of a company, for example) that should not exchange data using the local network (although they could make it through a router or a switch layer 3 and 4).

A VLAN consists of two or more networks of computers that behave as if connected to the same PCI, even if they are physically connected to different segments of a local area network (LAN). Network administrators configure VLANs through software rather than hardware, which make them extremely strong.

Classification:

But the most common are the port-based VLAN (level 1), the virtual local area networks can be classified into four types depending on the level of the OSI hierarchy in which they operate:

• Level 1 VLAN (per port). Also known as "port switching". Why switch ports belong to the specified VLAN, VLAN members that are connecting to these ports. It does not allow user mobility; we should reconfigure the VLAN if the user physically moves. It is the most common and explained in detail in this article.

• VLAN Layer 2 MAC addresses. Hosts assigned to a VLAN based on their MAC address. It has the advantage that there is no need to reconfigure the switching device if the user changes their location, is connected to another port of the same or another device. The main disadvantage is that if there are hundreds of users would have to appoint the members one by one.

• VLAN level 2 protocol type. The VLAN is determined by the contents of the protocol type field of the MAC frame. For example, you would associate the IPv4 protocol VLAN 1, VLAN 2 to IPv6, VLAN 3 to AppleTalk, IPX VLAN 4 to...

• Level 3 VLAN subnet addresses (virtual subnet). The head of level 3 is used to map the VLAN to which it belongs. In this type of VLAN packets are, not the stations, who belong to the VLAN. Stations with multiple network protocols (level 3) will be in multiple VLAN.

VLAN higher levels. VLAN is created for each application: FTP, streaming media, email ... Belonging to a VLAN can be based on a combination of factors such as ports, MAC address, subnet, time of day, form of access, security conditions equipment.

VLAN designs:

Early network designers used to configure VLANs in order to reduce the size of a collision domain Ethernet segment and improve performance. When the switches accomplished this, because each port is a collision domain, its priority was to reduce the size of the broadcast domain. Because, if the number of terminals increases traffic distribution and consumption of CPU processing unwanted broadcast traffic. One of the most efficient ways to achieve reducing the broadcast domain is the division of a large network in multiple VLANs.