1. Introduction to Network-2-

2. Network types Local Area Network (LAN) High speed, low error data networks that covers small geographic area. There are different types of LAN networks: 1.Ethernet networks 2.Token-Ring Network 3.FDDI

3. Transmission Types There are two types: Baseband Transmission: Uses digital signals sent over a cable without modulation Sends binary values (0s and 1s) as pulses of different voltage levels Entire bandwidth of the cable is used to transmit a single data signal Signal flow can be bi-directional Data transmission in computer Broadband Transmission: An analog transmission technique which may use multiple communication channels simultaneously Each data channel is represented by modulation on a particular frequency band, for which sending or receiving equipment must be tuned Signal flow is one-way only; two channels are necessary for computers to send/receive data TV and Radio transmission

4. 1-Ethernet Networks is the most widely used LAN technology first implemented by the DIX (Digital, Intel, Xerox) group Ethernet Networks are based on CSMA/CD (Carrier SENSE Multiple ACCESS/ Collision Detect) Process. Most popular network world wide. Many variation within Ethernet networks depending upon: Topology Type of cable used

5. 1-Ethernet Networks All of them use Baseband transmission

6. 1-Ethernet Networks Gigabit Ethernet Provides a greatly increased speed and operates over different media. Mostly used for high speed LAN backbone server connectivity Gigabit Interface Converter (GBIC) Input/output device Plugs into a Gigabit Ethernet port (slot) Links the port with the physical media used by the network

7. 2-Token Ring Networks Was developed By IBM. The most highly used network implementation; token Ring is now only second to Ethernet. Two standards of Token Ring networks are: IBM Token Ring IEEE The tow standards are almost identical and are compatible to each other.

8. 2-Token Ring Networks There are a few specification adjustment as under: IBM Token Ring IEEE TopologyStar/RingNo spec/Ring MediaTwisted pair No spec

9. 3-FDDI Networks Fiber Distributed Data interface is a 100 Mbps Token Ring Network based on Dual Ring Topology. Uses a Dual Ring architecture with counter rotation between each ring. The dual ring consist of a primary and a secondary ring. The primary ring used for data transmission, and the secondary ring remain idle.

10. Ethernet Frames Data when transmitted from one system to another is divided into segments. Further information is added to the segment and this process is called encapsulation. Filed added before the data called header and the fields added after the data called trailer. Heeare+Data+Trailer= Frame. The frames for Ethernet and IEEE 802.3 are almost identical. But they have some diifrent.

11. destinationsource addr length data FCS IEEE 802.3: Ethernet Encapsulation : data FCS 46-1500 bytes 7 6 2 4 8 4 46-1500 Preamble: tells receiving station that a frame is coming SOF( start of Frame): indicates the beginning of the frame. Destination add: network /node address of destination device Source add: network /node address of sending device Length: number of bytes of data that follow this filed. Type: specifies the upper-layer protocol to receive the data after Ethernet processing is complete. Data: packet of information FCS (Frame check sequence): is a cyclic redundancy check (CRC) SOFPreamble 16 addr Type 2 Preamble destinationsource addr 66

12. Connection-Oriented/Connectionless Protocols Connection Oriented Protocol Provides flow control and reliable data delivery services. This protocols is achieved by the following techniques: Acknowledgment Retransmission Sequencing Flow control Slow compared to connectionless protocol. In TCP/IP protocol suite, the connection oriented protocol is TCP. Examples of applications which use TCP are FTP, HTTP, …….ect SR frame sent Acknowledgment

13. Connection-Oriented/Connectionless Protocols Connectionless Protocols Provides minimal service and dose not guarantee for delivery of packets. So it is unreliable. In TCP/IP protocol suite, the connectionless protocol is UDP( User Datagram Protocol). UDP works faster than TCP but is unreliable. If the datagrams arrive at the destination computer out of sequence, UDP will drop the packets. Examples of applications which use UDP are TFTP, SNMP, …….ect

14. Carrier Sense Multiple Access/ Collision Detect (CSMA/CD) Ethernet LANs manage the signals on a network by a process called CSMA/CD. Before sending data, computer listen to the network: If it already in use, computer wait. If it not in use, computer sends its data. A collision might occur when two stations listen for network traffic, hear none, and transmit simultaneously. In this case, both transmissions are damaged, and the data is lost. And the computers retransmit at some later time. CSMA/CD stations must be able to detect collision, so that they know when they must retransmit. Signal is referred to as carrier. NIC senses the carrier and then restrains itself from broadcasting a signal. CSMA/CD is a contention based tecnique.

15. LAN/ WAN Devices Repeaters Regenerate and propagate signals from one another. They don’t change any information being transmitted, and they cannot filter any information. Help to extend the distances of networks

16. LAN/ WAN Devices Repeaters

17. LAN/ WAN Devices Hubs Hubs Serves as the center of a star topology network. Sometimes referred to as a multiport repeater. Or in Ethernet, a concentrator. Provides no forwarding intelligence Amplifies signals. Propagates signals through the network. Dose not filter data packets based on destination. No path determination or switching. Used as network concentration point.

18. LAN/ WAN Devices Hubs

19. LAN/ WAN Devices Bridges/ Switches Bridges/ Switches Both do the same job Connect LAN segments. Reduce traffic. Use a table of MAC address to determine the segment on which a frame needs to be transmitted. Switches are also referred as multiport bridges. BridgeSwitch Max number of ports-16Max number of ports- No limit Uses software for switchingUses Hardware –ASIC (Application Specific Interface Circuit) Slow Faster Low port density High port density at a lower cost

20. LAN/ WAN Devices Switches Switches Enable dedicated access Eliminate collisions and increses capacity. Supports multiple conversation at the same time. Function of a switch: Address learning Forward/ filter decision. Loop avoidance Build and maintain MAC address tables called as content addressable Memory (CAM) automatically.

21. LAN/ WAN Devices Switches

22. How Switches Operate.

23. LAN/ WAN Devices Collision Domain When computers are connected to a hub, if any tow computers send frames at the same time, they collide and data destroyed. All computers connected to hub are said to be in the same collision domain. Switches/Bridges segment collision domain.

24. LAN/ WAN Devices Broadcast Domain When a broadcast is sent by a computer to a switch or a hub, it forwarded to all ports. Switch or Hub do not filter broadcast traffic Routers segment Broadcast Traffic

25. LAN/ WAN Devices Routers Routers used for: Routing: IS the process of determining the best path to a destination. Switching: Once the best path is determined, the packets are forwarded from the source to destination port. Segmenting networks into subnets to reduce broadcast. Interconnecting WANs links. Interconnecting different types of networks. Interconnecting different types of Media. Filtering traffic using access link.

26. LAN/ WAN Devices Routers

27. Multicast/ Unicast/ Broadcast Unicast: Point to point communication between two computers within a network. The destination address will be the IP Address/ MAC Address. Unicast process The source addresses the packet with the destination address The packet is sent into the network The network delivers the packet to the destination.

28. Multicast/ Unicast/ Broadcast Multicast A single data packet is copied and sent to specific destination on the network Multicast Process The source addresses the packet using a multicast address. The packet is sent into the network. The network copies the packet. A copy is delivered to each destination that is included in the multicast address.

29. Multicast/ Unicast/ Broadcast Broadcast A single data packet is copied and sent from a source to all destinations on the network. Routers don’t allow Broadcast Traffic (Flooding). Broadcast Process: The source addresses the packet with the broadcast address. The packet is sent into the network. The network copies the packet. The packet copies are delivered to all destinations on the network