17023 Networking Basics

Networking Concepts Devices What is a Switch? A switch is used in a wired network to connect Ethernet cables from a number of devices together. The switch allows each device to talk to the others. Switches aren't used in networks with only wireless connections, since network devices such as routers and adapters communicate directly with one another, with nothing in between. Although you can use the ports on the back of a router or modem to connect a few Ethernet devices together, depending on the model, switches have a number of advantages:

Switches keep traffic between two devices from getting in the way of your other devices using the same network. Switches allow control of who has access to various parts of the network. Switches allow you to monitor usage. Switches allow communication (within your network) that's even faster than the Internet. High-end switches have pluggable modules to tailor them to network needs. Switches targeted for home uses, or for small businesses.

Hub A hub is a small rectangular box, often made of plastic, that receives its power from an ordinary wall outlet. A hub joins multiple computers (or other network devices) together to form a single network segment. On this network segment, all computers can communicate directly with each other. Ethernet hubs are by far the most common type, but hubs for other types of networks such as USB also exist. A hub includes a series of ports that each accept a network cable. Small hubs network four computers. They contain four or sometimes five ports, the fifth port being reserved

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Switches allow dozens of devices to connect.

for "uplink" connections to another hub or similar device. Larger hubs contain eight, 12, 16, and even 24 ports. three different types of hubs exist: passive active intelligent

Intelligent hubs add extra features to an active hub that are of particular importance to businesses. An intelligent hub typically is stackable (built in such a way that multiple units can be placed one on top of the other to conserve space). It also typically includes remote management capabilities via SNMP and virtual LAN (VLAN) support. Hubs remain a very popular device for small networks because of their low cost. Repeater A network device used to regenerate or replicate a signal. Repeaters are used in transmission systems to regenerate analog or digital signals distorted by transmission loss. Analog repeaters frequently can only amplify the signal while digital repeaters can reconstruct a signal to near its original quality. In a data network, a repeater can relay messages between subnetworks that use different protocols or cable types. Hubs can operate as repeaters by relaying messages to all connected computers. A repeater cannot do the intelligent routing performed by bridges and routers. Repeaters attempt to preserve signal integrity and extend the distance over which data can safely travel. Router Routers operate at the network layer OSI Model's layer 3. It is a device that forwards data packets along networks. A router is connected to at least two networks,

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Passive hubs do not amplify the electrical signal of incoming packets before broadcasting them out to the network. Active hubs, on the other hand, do perform this amplification, as does a different type of dedicated network device called a repeater. Some people use the terms concentrator when referring to a passive hub and multiport repeater when referring to an active hub.

commonly two LANs or WANs or a LAN and its ISP(s) network. Routers are located at gateways, the places where two or more networks connect. Routers use headers and forwarding tables to determine the best path for forwarding the packets, and they use protocols such as ICMP to communicate with each other and configure the best route between any two hosts. Very little filtering of data is done through routers. Many different types of routers have been developed so that the information coming over your broadband connection can be sent to a variety of different receivers including your computer, your phone, and others.

Modem, short for modulator-demodulator is an electronic device that converts a computer’s digital signals into specific frequencies to travel over telephone or cable television lines. At the destination, the receiving modem demodulates the frequencies back into digital data. Computers use modems to communicate with one another over a network. Modems are referred to as an asynchronous device, meaning that the device transmits data in an intermittent stream of small packets. Once received, the receiving system then takes the data in the packets and reassembles it into a form the computer can use. Below are the three available versions of a computer Modem that can be used in computers. Internal modem that connects to a PCI slot inside a newer desktop computer or ISA slot on an older computer. External modem is located within a box and is hooked up externally to the computer, usually the Serial Ports or USB port. Removable modem that is used with older laptops PCMCIA slot and is removed when you need the PCMCIA slot for another device, but are not planning on using the modem.

Bridge

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Modem

A bridge device filters data traffic at a network boundary. Bridges reduce the amount of traffic on a LAN by dividing it into two segments. In telecommunication networks, a bridge is a product that connects a local area network (LAN) to another local area network that uses the same protocol. Bridges operate at the data link layer (Layer 2) of the OSI model. Bridges inspect incoming traffic and decide whether to forward or discard it. An Ethernet bridge, for example, inspects each incoming Ethernet frame including the source and destination MAC addresses, and sometimes the frame size in making individual forwarding decisions. Bridges learn which addresses are on which network and develop a learning table so that subsequent messages can be forwarded to the right network.

Network Card Network Interface Card, a NIC is also commonly referred to as an Ethernet card and network adapter and is an expansion card that enables a computer to connect to a network such as a home network or the Internet using an Ethernet cable with a RJ-45 connector. The most common form of network card in current use is the Ethernet card. A network card commonly found in most desktop computers today that do not already have an integrated network on their motherboard. These days laptop computers do have a built-in wireless network interface card. Network Cables Network Cables are used to connect switches to computers and/or routers. They are produced in a variety of colors so they are easily distinguishable to identify their purpose. The most common types of network cables are: Ethernet, Cat5, Cat5e, and Cat6 cables. Ethernet Ethernet is a computer networking technology for local area networks (LANs) which has been used almost 30 years, largely replacing other competing LAN standards such as the token ring, FDDI, and ARCNET. It is the most commonly used network cable for Windows and Macs and necessary for network setup. This type of network cable defines a number of wiring and signaling standards for a physical layer, through

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Bridges serve a similar function as switches, that also operate at Layer 2. Traditional bridges, though, support one network boundary, whereas switches usually offer four or more hardware ports. Switches are sometimes called "multi-port bridges" for this reason. A bridge is sometimes combined with a router in a product called a brouter.

means of access at the Media Access Center (MAC)/DLL, and a common addressing format.

Cat5/Cat5e Category 5 Ethernet cables, or commonly known as Cat5s or “Cable and Telephone”, are twisted pairs of cables used for high signal networks. A regular Cat5 cable is identified as being unshielded and a Cat5e specification incorporates a shield. This general type of cable is used in structured cabling for computer networks such as Ethernet, and is also able to carry basic voice signals. Cat 5 Network Cable is the standard type of cable for networking your computers and other network devices such as printers, copiers, cameras, etc. These cables can support frequencies of up to 100 MHZ, It is most commonly used for 100 Mbit/s networks.

A Cat6 cable is a standard for Gigabit Ethernet as well as other network protocols that is also backward compatible with the Category 5/5e and Category 3 cable standards. A Cat-6 features even more stringent specifications than a Cat5e for crosstalk and system noise. It provides performance of up to 250 MHZ and is also suitable for 10 Gigabit Ethernet standards. Crossover Cable A crossover cable directly connects two network devices of the same type to each other over Ethernet. A crossover cable is also sometimes known as a null modem. Crossover cable is used to connect two like devices without the use of an uplink port. The crossover cable can be used to connect : - Switch to switch - Hub to hub - Host to host - Hub to switch - Router direct to host

Straight Through Cable:

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Cat6

A network cabling that connects a computer to a network device. For example, straight through cables are cables that connect a computer to a network hub, network switch, and network routers. Straight-through cable is also commonly referred to as patch cable. RollOver Cable: A rollover cable is a network cable that connects a computer terminal to a network router’s console port. It is normally flat and light blue so as to distinguish it from other network cable types. Rollover cables are also known as Yost cables or Yost Serial Device Wiring Standard connectors.

Network topology

Types Physical topology refers to the placement of the network's various components, including device location and cable installation. logical topology shows how data flows within a network, regardless of its physical design. Physical Topology Types: In the bus network topology, every workstation is connected to a main cable called the bus. Therefore, in effect, each workstation is directly connected to every other workstation in the network. In the star network topology, there is a central computer or server to which all the workstations are directly connected. Every workstation is indirectly connected to every other through the central computer. In the ring network topology, the workstations are connected in a closed loop configuration. Adjacent pairs of workstations are directly connected. Other pairs of workstations are indirectly connected, the data passing through one or more intermediate nodes. If a Token Ring protocol is used in a star or ring topology, the signal travels in only one direction, carried by a so-called token from node to node. In this all of the nodes

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Network topology is the arrangement of the various elements (links, nodes, etc.) of a computer. In communication networks, a topology is a usually schematic description of the arrangement of a network, including its nodes and connecting lines.

are connected in a closed loop. Messages travel around the ring, with each node reading those messages addressed to it. One main advantage to a ring network is that it can span larger distances than other types of networks, such as bus networks, because each node regenerates messages as they pass through it. The mesh network topology employs either of two schemes, called full mesh and partial mesh. In the full mesh topology, each workstation is connected directly to each of the others. In the partial mesh topology, some workstations are connected to all the others, and some are connected only to those other nodes with which they exchange the most data. The tree network topology uses two or more star networks connected together. The central computers of the star networks are connected to a main bus. Thus, a tree network is a bus network of star networks.

LAN - Local Area Network WLAN - Wireless Local Area Network WAN - Wide Area Network MAN - Metropolitan Area Network SAN - Storage Area Network, System Area Network, Server Area Network, or sometimes Small Area Network CAN - Campus Area Network, Controller Area Network, or sometimes Cluster Area Network PAN - Personal Area Network DAN - Desk Area Network

Explaining the various Networks: LAN - Local Area Network A LAN connects network devices over a relatively short distance. A networked office building, school, or home usually contains a single LAN, though sometimes one building will contain a few small LANs (perhaps one per room), and occasionally a

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Types of Networks:

LAN will span a group of nearby buildings. In TCP/IP networking, a LAN is often but not always implemented as a single IP subnet. In addition to operating in a limited space, LANs are also typically owned, controlled, and managed by a single person or organization. They also tend to use certain connectivity technologies, primarily Ethernet and Token Ring. WAN - Wide Area Network As the term implies, a WAN spans a large physical distance. The Internet is the largest WAN, spanning the Earth.

A WAN differs from a LAN in several important ways. Most WANs (like the Internet) are not owned by any one organization but rather exist under collective or distributed ownership and management. WANs tend to use technology like ATM, Frame Relay and X.25 for connectivity over the longer distances. LAN and WAN are by far the most popular network types. Wireless Local Area Network - a LAN based on WiFi wireless network technology Metropolitan Area Network - a network spanning a physical area larger than a LAN but smaller than a WAN, such as a city. A MAN is typically owned an operated by a single entity such as a government body or large corporation. Campus Area Network - a network spanning multiple LANs but smaller than a MAN, such as on a university or local business campus. Storage Area Network - connects servers to data storage devices through a technology like Fibre Channel. System Area Network - links high-performance computers with high-speed connections in a cluster configuration. Also known as Cluster Area Network.

IP Every computer that communicates over the Internet is assigned an IP address that uniquely identifies the device and distinguishes it from other computers on the

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A WAN is a geographically-dispersed collection of LANs. A network device called a router connects LANs to a WAN. In IP networking, the router maintains both a LAN address and a WAN address.

Internet. An IP address consists of 32 bits, often shown as 4 octets of numbers from 0-255 represented in decimal form instead of binary form. IP is an address of a computer or other network device on a network using IP or TCP/IP. For example, the number "166.70.10.23" is an example of such an address. These addresses are similar to an addresses used on a house and is what allows data to reach the appropriate destination on a network and the Internet. There are five classes of available IP ranges: Class A, Class B, Class C, Class D and Class E, while only A, B, and C are commonly used. Each class allows for a range of valid IP addresses.

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Below is a listing of these addresses.

IEEE 802.11 WLAN Standards IEEE 802.11 is a set of standards for wireless network to provide wireless devices with a communication in the 2.4, 3.6 and 5 GHz frequency bands. They are originally developed and maintained by the IEEE (Institute of Electrical and Electronics Engineers) LAN/MAN Standards Committee (LMSC).

The first standard was created by IEEE in 1997 and had been named as 802.11. It uses unregulated radio signaling frequency (2.4 GHz) but only supported up to 2 Mbps maximum network bandwidth. Specific physical layers that enabled three faster radio layers had been defined by subsequent amendments of IEEE 802.11:

802.11b

802.11b was created based on the specification of original 802.11 in July 1999, and it support network bandwidth up to 11 Mbps.

Pros of 802.11b – cost is cheapest; signal range is very good and not easily to be obstructed. Cons of 802.11b – maximum speed is still slower; home appliances may interfere on the unregulated frequency band. 802.11a A second extension to the original 802.11 standard was created and called 802.11a. Due to its higher cost, 802.11a is usually found on business networks whereas 802.11b better serves the home market. 802.11a supports up to 54 Mbps network bandwidth and provides 8 radio channels in the 5 GHz frequency band. Because of this higher frequency, the range of 802.11a networks is also shortened. In addition, the higher frequency also makes the signal of 802.11a to have more difficulty in penetrating walls and other obstacles. Pros of 802.11a – faster maximum speed; regulated frequencies can get rid of signal interference from other home appliances. Cons of 802.11a – expensive in cost; shorter range signal and more easily to be obstructed. 802.11g 802.11g was created to combine the best of both 802.11a and 802.11b and supports network bandwidth up to 54 Mbps. It uses the 2.4 GHz frequency for wider range. 802.11g is backwards compatible with 802.11b, which means the access point of

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802.11b uses unregulated radio signaling frequency (2.4 GHz) as same as the original 802.11 standard. It provides 3 radio channels. By using this frequency, the manufacturing costs could be lower down. Because of unregulated signal, 802.11b could incur interference from other appliances using the same 2.4 GHz range, such as microwave ovens, cordless phones. However, the interferences can be avoided by installing 802.11b a reasonable distance from other appliances.

802.11g will just work fine with all the wireless network adapters of 802.11b, and vice versa. Pros of 802.11g – fast maximum speed; signal range is very good and not easily to be obstructed. Cons of 802.11g – cost is higher than 802.11b; other appliances may interfere on the unregulated.

802.11n is the newest IEEE standard in the 802.11 family. It improves on 802.11g in the amount of bandwidth by using multiple wireless signals and antennas instead of one. This is a technology called MIMO (multiple-input multiple-output). It will also operate on the 2.4 GHz band. Presently the development of this standard is still in progress. But when this standard is finalized, 802.11n connections will be able to support data rates up to 100 Mbps. 802.11n also offers better range over earlier 802.11 standards due to its increased signal intensity.

Pros of 802.11g –best signal range and fastest in maximum speed; more ability to resist signal interference from other sources. Cons of 802.11g –cost is higher than 802.11g; the use of multiple signals may massively be interfered by nearby 802.11b or 802.11g based networks. IEEE Lan IEEE 802.3 Ethernet (CSMA/CD) A method called Carrier Sense Multiple Access with Collision Detection (CSMA/CD) was used to send data over shared single co-axial cable connected to all computers on a network. In this method, the computer terminals (also called as stations) transmits the data over cable whenever the cable is idle, If more than one station transmit at same time and if they collide, the transmission will be stopped by such stations. They will wait for some random time and restart transmission. The concept of sharing single cable or wire between multiple stations was used for first time in Hawaiian Islands. It was called ALOHA systems; built to allow radio communication between machines located at different places in Hawaiian Islands. Later Xerox PARC built a 2.94 mbps CSMA/CD system to connect multiple personal computers on a single cable. It was named as Ethernet.

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802.11n

Ethernet or IEEE802.3 standards only define MAC (Data link) and Physical layer of standard OSI model. Ports Ports are classified into 3 main categories.. 

Well Known Ports (Port numbers 0 - 1023)

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Registered Ports (Port numbers1024 - 49151)

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Private or Dynamic Ports (Port numbers 49152 - 65535)

Registered Ports The registered port numbers range from 1024-49151. Such ports are used by programs run by users in the system. Private/Dynamic Ports Private ports are not assigned for any specific purpose. its range are from range 49152–65535 Iportant Port Numbers Under TCP and UDP 21

TCP

FTP (File Transfer Protocol)

22

TCP/UDP SSH (ssh,scp copy or sftp)

23

TCP/UDP Telnet

25

TCP/UDP

SMTP (for sending outgoing emails)

53

TCP/UDP

DNS Server (Domain name service for DNS requests)

67 68

UDP TCP

DHCP Server DHCP Client

110 TCP

POP3 (for receiving email)

443 TCP

Secure HTTP over SSL (https)

465 TCP

Secure SMTP (email) using SSL

990 TCP/UDP Secure FTP using SSL 993 TCP

Secure IMAP protocol over SSL (for emails)

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Well Known Ports Well known ports are used by system or processes run by root or with specific previleges. The port numbers range from 0 to 1023.

1433 TCP/UDP Microsoft SQL server port 3306 TCP/UDP MySQL Database Server 8080 TCP

HTTP port (alternative one for port 80)

OSI : Open Systems Interconnection Three are Sever Layers of OSI Model : 7) Application Layer : The application layer provider different services to the application. Example of services provided by this layer are file transfer, electronic messaging e-mail, virtual terminal access and network management. 6) Presentation Layer : The Presentation layer is responsible for protocol conversion, date encryption/decryption, Expanding graphics command and the date compression. This layer makes the

5) Session Layer : This layer is responsible for establishing the process-to-process communication between the host in the network. This layer is responsible for establishing and ending the sessions across the network. The interactive login is an example of services provided by this layer in which the connective are re-connected in care of any interruption. 4) Transport Layer : This layer is responsible for end-to-end delivers of messages between the networked hosts. It first divides the streams of data into chunks or packets before transmission and then the receiving computer re-assembles the packets. It also guarantee error free data delivery without loss or duplications. 3) Network Layer : This layer is responsible for translating the logical network address and names into their physical address ( MAC address). This layer is also responsible for addressing, determining routes for sending and managing network problems such as packet switching, data congestion and routines. 2) Data Link Layer : Data link layer is responsible for controlling the error between adjacent nodes and transfer the frames to other computer via physical layer. Data link layer is used by hubs and switches for their operation. 1) Physical Layer : Physical Layer is responsible for transmitting row bit stream over the physical cable. The physical layer defines the hardware items such as cables, cards, voltages etc.

Thanks You

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communications between two host possible.