Network Cabling

Network Cabling: - Mainly use three types of cables.

Coaxial Cable: - This cable is used in early 90 for computer networking and the connector which is use in coaxial cable is BNC (Bennotte Navel Connector). Coaxial cable, also called coax, is used to transmit radio frequency (RF) signals. It has low emission losses and provides protection from electromagnetic interference, allowing signals with low power to be transmitted over longer distances. Coaxial cable is comprised of an inner core, insulator, shield, and outer cover. It is called coaxial because these sections all share the same axis. There are many different types of coaxial cable, each one with different physical and electronic properties designed for specific tasks. It is commonly used for carrying cable television signals along suburban streets and into homes.

Two types of cables: -

Thicket: - Support 500 meters.

Thinnet: - Support 200 meters.

The advantages of Coaxial cable are:

- They are cheap to make

- Cheap to install

- Easy to modify

- Good bandwidth

- Great channel capacity

- Noise immunity due to low error rate

The disadvantages of Coaxial cable are:

- Problems with the deployment architecture

- Bidirectional upgrade required

- Great noise

- High installation costs

- Susceptible to damage from lightning strikes

Twisted Pair: - This is most common and mostly used cable. Twisted pair is categories under in cat sections. This cable has 4 pair (Eight Wire). The connected which is used in twisted pair is RJ-45. Twisted-pair cable is a type of cabling that is used for telephone communications and most modern Ethernet networks. A pair of wires forms a circuit that can transmit data. The pairs are twisted to provide protection against crosstalk, the noise generated by adjacent pairs. When electrical current flows through a wire, it creates a small, circular magnetic field around the wire. When two wires in an electrical circuit are placed close together, their magnetic fields are the exact opposite of each other. Thus, the two magnetic fields cancel each other out. They also cancel out any outside magnetic fields. Twisting the wires can enhance this cancellation effect. Using cancellation together with twisting the wires, cable designers can effectively provide self-shielding for wire pairs within the network media.

·        (STP) Shelled Twisted Pair.

·        (UTP) Unshelled Twisted pair.

UTP cable is a medium that is composed of pairs of wires. UTP cable is used in a variety of networks. Each of the eight individual copper wires in UTP cable \is covered by an insulating material. In addition, the wires in each pair are twisted around each other.

UTP cable relies solely on the cancellation effect produced by the twisted wire pairs to limit signal degradation caused by electromagnetic interference (EMI) and radio frequency interference (RFI). To further reduce crosstalk between the pairs in UTP cable, the number of twists in the wire pairs varies. UTP cable must follow precise specifications governing how many twists or braids are permitted per meter (3.28 feet) of cable.

UTP cable often is installed using a Registered Jack 45 (RJ-45) connector. The RJ-45 is an eight-wire connector used commonly to connect computers onto a local-area network (LAN), especially Ethernets.

Shielded twisted-pair (STP) cable combines the techniques of shielding, cancellation, and wire twisting. Each pair of wires is wrapped in a metallic foil (see Figure 8-3). The four pairs of wires then are wrapped in an overall metallic braid or foil, usually 150-ohm cable. As specified for use in Ethernet network installations, STP reduces electrical noise both within the cable (pair-to-pair coupling, or crosstalk) and from outside the cable (EMI and RFI). STP usually is installed with STP data connector, which is created especially for the STP cable. However, STP cabling also can use the same RJ connectors that UTP uses.

Fiber Optics: - Fiber optic cable is the most secure cables. The connector which is use in fibers optics. In this cables an optical wire (glass) is used for data transfer.

Main two type of fiber optics cable:-

Single Mode: - Single Mode cable is a single stand (most applications use 2 fibers) of glass fiber with a diameter of 8.3 to 10 microns that has one mode of transmission.  Single Mode Fiber with a relatively narrow diameter, through which only one mode will propagate typically 1310 or 1550nm. Carries higher bandwidth than multimode fiber, but requires a light source with a narrow spectral width.

Single-mode fiber gives you a higher transmission rate and up to 50 times more distance than multimode, but it also costs more. Single-mode fiber has a much smaller core than multimode. The small core and single light-wave virtually eliminate any distortion that could result from overlapping light pulses, providing the least signal attenuation and the highest transmission speeds of any fiber cable type.

Multi-Mode cable: - Multi-Mode cable has a little bit bigger diameter, with a common diameters in the 50-to-100 micron range for the light carry component (in the US the most common size is 62.5um). Most applications in which Multi-mode fiber is used, 2 fibers are used (WDM is not normally used on multi-mode fiber).  POF is a newer plastic-based cable which promises performance similar to glass cable on very short runs, but at a lower cost.

Multimode fiber gives you high bandwidth at high speeds (10 to 100MBS - Gigabit to 275m to 2km) over medium distances. Light waves are dispersed into numerous paths, or modes, as they travel through the cable's core typically 850 or 1300nm. Typical multimode fiber core diameters are 50, 62.5, and 100 micrometers. However, in long cable runs (greater than 3000 feet [914.4 meters), multiple paths of light can cause signal distortion at the receiving end, resulting in an unclear and incomplete data transmission so designers now call for single mode fiber in new applications using Gigabit and beyond. 

The connector which are use in fiber optics are:-

Software Required For Practical Of Cisco

Packet Tracer:-

Packet tracer is software which is made by Cisco system. It is used for all the practical of Cisco. This software gives a graphical interface of each and every device.

Microsoft Virtual PC:-

Microsoft virtual Pc is application software created by Microsoft for installation of multiple operating systems. Microsoft virtual pc has two key components.

·        Console: - Console is dialogue box in which OS retreating setting.

·         HDD:- It is a virtual HDD with having maximum space of 16 GB and this HDD covers all the data file of the OS.

COMMUNICATION MEDIA

COMMUNICATION MEDIA:-

• Half Duplexing: - Means when a particular system sends data that time and can can’t receive any type of data.

• Full Duplexing: - Means when a system send data on that time and that system is also able to receive data.
  
  
  
• Broadcasting: - Means sending a data to all the systems.
  
   
• Multicasting: - It means sending a data to multiple systems.
  
  
  
• Unicasting: - It means sending of data to single system.

           

OSI LAYER MODEL

The International Standards Organization (ISO) developed the Open Systems Interconnection (OSI) Reference Model to define functional communications standards. This reference model is widely used by equipment manufacturers to assure their products will interoperate with products from other vendors. The OSI model describes the functions that are performed in data communications. The model architecture is seven layers those are listed below with each layer defining specific functions.

APPLICATION LAYER: - Provide interface with the network and define a format. Any user application that requires network communication accesses the communication resources through this layer. This layer also is responsible for finding and determining the availability of communication partners. Typical applications in the TCP/IP protocols are Simple Mail Transfer Protocol (SMTP), Telnet, and File Transfer Protocol (FTP).

PRESENTATION LAYER: - Provide encryption and processing work. The Presentation layer is responsible for encoding and decoding data that is passed from the application layer to another station on the internet work. This layer is responsible for encoding data in a format that the receiving station can interpret and for decoding data received from other stations. Data compression and encryption are accomplished at this layer. Typical coding schemes include ASCII, EBCDIC, MPEG, GIF, and JPEG.

SESSION LAYER: - Distribute session, creating, marinating and termination a session.  The session layer is responsible for creating, managing and termination sessions that are used by entities at the presentation layer. The session layer is responsible for coordinating the service requests and responses generated and received by a station when it is communication with other entities on the internet work.

TRANSPORT LAYER: - Provide data transmission, error correction, segmentation, and sequencing.    The Transport layer implements reliable internet work data transport services that are transparent to upper-layer protocols. The services include flow control, multiplexing, and error checking and recovery. If virtual circuits are needed for the communication to be accomplished, they are built and maintained at this layer. Flow control is responsible for making sure that a sending station does not transmit data faster than the receiving station can process it. Multiplexing allows multiple applications to share a common network interface. Error checking is implemented to discover errors on transmission and to provide a recovery mechanism when errors are found. Typical error recovery includes retransmission of the data.

NETWORK LAYER: - Provide logical addressing and routing. The Network layer defines routing services that allow multiple data links to be combined into an internet work. The Network layer defines network-addressing schemes that logically identify network devices. The logical network addresses are different from the physical addresses defined at the MAC layer, and are used by routing protocols running at this level to transfer packets from one network to another. The most common network addressing protocols are IP, IPX, and AppleTalk. Typical routing protocols that run at this level are RIP, OSPF, IGRP, and NLSP.

DATA LINK LAYER: - Provide physical addressing, framing, send acknowledgment and logic link control. The Data Link layer provides reliable transit of data across a physical network link. The Data Link layer also defines the physical network-addressing scheme, such as the MAC Address on network interface cards in a workstation connected to a LAN. The Data Link layer also defines the topology of the network (bus, star, dual ring, and so on). Flow control at the Data Link layer is defined to ensure receiving stations are not overrun with data before they can process data already received. The Institute of Electrical and Electronics Engineers (IEEE) has redefined the Data Link layer into two sublayers. The sublayers are the Logical Link Control (LLC) layer and the Media Access Control (MAC) layer. The LLC and MAC sublayers are defined in the IEEE 802.2 standards. The LLC manages communications between devices over a single link of a network. The MAC sublayer manages access to the physical medium from multiple upper-level protocols. The MAC layer also defines the MAC address, which uniquely identifies devices at the Data Link layer.

PHYSICAL LAYER: - Covers data into bit and all devices, connector, cables come under this layer. The Physical layer defines the parameters necessary to build, maintain, and break the physical link connections. It defines the characteristics of the connectors, data transmission rates and distances, and the interface voltages.

NOTE: - First of all TCP/IP base on these layer and made OSI Model.

1.      Application.

2.      Host to Host.

3.      Internet

4.      Network Access layer

Then to understanding TCP/IP need to design OSI Model.

Application Layer Presentation Layer Session Layer

Application

Transport Layer

Host to Host

Network Layer Data Link Layer

Internet

Physical Layer

Network Access Layer



Networking Topology

Topology: - Networking topology means designing of network according to physical and logical aspects. Physical means actual structure of any network and logical means the data transfers between the networks.

                        

1. BUS: - In a bus topology all the systems are connected to a single back bone cable.
   
   
   
   
   
   
   
2. STAR: - This topology is the best and mostly used in the current environment. In this topology all the system are directly connected with the centralized devices i.e. switch or hub.
   
   
   
   
   
3. RING:- Ring topology is created by IBM. In this topology all the system are connected in the ring format. A device which is use in ring topology (MAU) Multi station unit.
   
   
   
   
   
   
4. MESH: - Mesh topology is most uncommon topologies. In this topology all the systems are connected with the other system multiple path names.
   
   
   
   
   
   
   
5. HYBRID: - When we mix two topologies that topology is called hybrid.

6. TREE: - When we combined multiples stars in a network will be called tree topology.

Note:-

• CSMA/CD: - Carrier sense multiple access /collision domain, Short for Carrier Sense Multiple Access / Collision Detection, a set of rules determining how network devices respond when two devices attempt to use a data channel simultaneously (called a collision). Standard Ethernet networks use CSMA/CD to physically monitor the traffic on the line at participating stations. If no transmission is taking place at the time, the particular station can transmit. If two stations attempt to transmit simultaneously, this causes a collision, which is detected by all participating stations. After a random time interval, the stations that collided attempt to transmit again. If another collision occurs, the time intervals from which the random waiting time is selected are increased step by step. This is known as exponential back off.

• CSMA/CA:- Carrier sense multiple access /collision avoidance, Short for Carrier Sense Multiple Access/Collision Avoidance, a network contention protocol that listens to a network in order to avoid collisions, unlike CSMA/CD that deals with network transmissions once collisions have been detected. CSMA/CA contributes to network traffic because, before any real data is transmitted, it has to broadcast a signal onto the network in order to listen for collision scenarios and to tell other devices not to broadcast.

Networking Model

Networking: - Networking means simple data transfer between two computer, devices, and equipments.

Networking has main four models:-

• LAN: - Local area network means a small group of computer which can communicate with each other. Eg: - Small office network, building, and can be extended up to two building.
  
  

• MAN: - Metropolitan area network is that network when more than one lan exists when network covers city that network will be called Man.
  
  
  
  
  
  • WAN:- Wide Area Network, when the network spreads to country and routing starts then that network will be call Wan.
    
    
    
    
    
  • PAN:- Private Area Network, when in a wan private line (Leased line) are involved that network will be called Pan.