1. Lecture 2 unit 1

2. Network components Connectors Transceivers Media converter Repeater
Network interface card
Hub
Router
Gateway
Switch

3. Connectors
Connectors are used to connect guided media to the computers.
Varieties of connectors are available for different types of cable.
Major categories of connectors are -
UTP cable connectors
Co-axial cable connectors
Fiber Optic cable connectors

4. UTP cable connectors.
Most commonly used connector for UTP cable is Registered Jack 45 (RJ 45).
The RJ 45 is a keyed connector i.e. they can be inserted in only one way.
For one data line, with programming resistor.
RJ-45 conductor data cable contains 4 pairs of wires each consists of a solid colored wire and a strip of the same color.
There are two wiring standards for RJ-45 wiring: T-568A and T-568B. Although there are 4 pairs of wires, 10BaseT/100BaseT Ethernet uses only 2 pairs: Orange and Green.
The other two colors (blue and brown) may be used for a second Ethernet line or for phone connections. The two wiring standards are used to create a cross-over cable (T-568A on one end, and T-568B on the other end), or a straight-through cable

5. RJ 45 Male
RJ 45 Female

6. Co-axial cable connectors
Co-axial cable connectors are also known as BNC connector.
BNC connector are used in cable TV’s, Ethernet network.
BNC connectors can branch out a cable for connection to a computer or other device.
Three different variations of BNC connectors are BNC connector, BNC-T and BNC terminator.

8. Fiber Optic cable connectors
Three different types of connectors are used for connecting Fiber Optic cable.
Those are –
Subscriber channel (SC) connector.
Straight tip (ST) connector.
MT-RJ connector.
SC connector are general purpose connectors. It has push pull type locking system.

9. ST connectors are most suited for networking device.
It is more reliable than SC connector.
ST connectors has bayonet type locking system.

10. MT RJ connector is similar to RJ 45 connector .
MT-RJ stands for Mechanical Transfer Registered Jack. MT-RJ is a fiber-optic Cable Connector that is very popular for small form factor devices due to its small size.
Housing two fibers and mating together with locating pins on the plug, the MT-RJ comes from the MT connector, which can contain up to 12 fibers. 
The MT-RJ is commonly used for networking applications. Its size is slightly smaller than a standard phone jack and just as easy to connect and disconnect. It's half the size of the SC Connector it was designed to replace. View all Fiber Optic Connectors.

12. Transceivers
Transceivers are the combination of transmitter and receiver.
Transceivers are also called as medium attachment unit (MAU).
Transceivers connects medium to the physical layer, hence they are medium dependent. It means that different media needs different types of transceivers, so that an appropriate signal for each type of medium can be generated.
Transceivers transmit and receive signal over the medium.
It also detects the collision.

13. Medium Dependent Interface
To Physical layer
Collision RX TX
transceiver
Medium Dependent Interface
Medium

14. Media converter
Media converter interconnect different cable types like twisted pair, fiber, and thin or thick co-axial cable within an existing network.
They are often used to connect newer 100-Mbps, gigabit Ethernet, or ATM equipment to existing networks, which are generally 10BASE-T, 100BASE-Tor a mixture of both.
Media converters offers an inexpensive alternative to repeater.
Media converters are typically protocol specific and are available to support a wide variety of network types and data rates. They are available as physical layer or Layer 2 switching devices, and media converters with Layer 2 switching capability provide rate-switching and other advanced features.

15. Repeater
Repeater is a device that receives a digital signal on an electromagnetic or optical transmission medium and regenerates the signal along the next leg of the medium.
It operates only in the physical layer.
Signal that carry information within a network can travel a fixed distance before attenuation endangers the integrity of data.
A repeater receives a signal and before it become too weak or corrupted, regenerates the original bit pattern. The repeater then sends the refreshed signal.

17. Network interface card
A network interface card (NIC) is a computer circuit board or card that is installed in a computer so that it can be connected to a network.
A network interface card NIC also known as a network interface controller, network adapter, LAN adapter.
Some NIC cards work with wired connections while others are wireless. Most NICs support either wired Ethernet or WiFi wireless standards.
When NIC transmit data on network, it convert data from parallel to serial then encodes and compress it.

18. When NIC receives data, it translates the electrical signal into equivalent binary data bits which can be accepted by computer.

19. Hub
Hub is a device for connecting multiple Ethernet devices together and making them act as a single network segment. It has multiple input/output (I/O) ports, in which a signal introduced at the input of any port appears at the output of every port except the original incoming.
Repeater hubs also participate in collision detection, forwarding a jam signal to all ports if it detects a collision.
There are three main types of hubs
Passive
Active
Intelligent