Contributed by Tan Wee Kiong

1. Disclaimer This is slides taken from Cisco Certified Network Associate Lesson Slides. Please do not distribute this around. This is only meant for reference. Hope this helps some understand better. There are also some extra information for those interested to know more. Contributed by Tan Wee Kiong

2. No matter how you send your messages, no matter which physical medium you use, bandwidth is limited. This is due both to the laws of physics and to current technological advances.

3. Throughput usually refers to actual, measured, bandwidth, at a specific time of day, using specific internet routes, while downloading a specific file. Some of the factors that determine throughput and bandwidth include the following: •internetworking devices •type of data being transferred •topology •number of users •user's computer •server computer •power and weather-induced outages •and many other reasons.

4. An important part of networking involves making decisions about which medium to use. This often leads to questions regarding the bandwidths that the user's applications require. The graphic summarizes a simple formula that will help you with such decisions

5. Protocol • Protocol is a set of rules, or an agreement, that determines the format and transmission of data that make communication on a network more efficient.

6. 7 layers of the OSI reference model • Layer 7:Application • Layer 6:Presentation • Layer 5:Session • Layer 4:Transport • Layer 3:Network • Layer 2:Data Link • Layer 1:Physical • All People Seem To Need Data Processing

7. The physical layer • Transmission of an unstructured bit stream over a physical link between end systems. • Electrical, mechanical, procedural and functional specifications • Physical data rate • Distances • Physical connector

8. The data-link layer • Provides for the reliable transfer of data cross a physical link. • Frames • Physical address • Network topology • Line discipline • Synchronization • Error control • Flow control

9. The network layer • Provides connectivity and path selection between two host systems that may be located on geographically separated networks. • Packets • Virtual circuits • Route, routing table, routing protocol • Logical address • Fragmentation

10. The transport layer • Provides reliable, transparent transfer of data over networks. • Segments, data stream, datagram • Connection oriented and connectionless • End-to-end flow control • Error detection and recovery • Segmentation & reassembly

11. The session layer • Establishes, manages, and terminates sessions between two communicating hosts. • Sessions • Dialog • Conversations • Data exchange

12. The presentation layer • Ensures that the information that the application layer of one system sends out is readable by the application layer of another system. • Format of data • Data structure • Data conversion • Data compression • Data encryption

13. The application layer • Is the OSI layer that is closest to the user; it provides network services to the user’s applications. • File transfer • Electronic mail • Terminal access • Word processing • Intended communication partners

14. 4 layers of the TCP/IP model • Layer 4:Application • Layer 3:Transport • Layer 2:Internet • Layer 1:Network access It is important to note that some of the layers in the TCP/IP model have the same name as layers in the OSI model. Do not confuse the layers of the two models.

15. The network access layer • Concerned with all of the issues that an IP packet requires to actually make the physical link. All the details in the OSI physical and data link layers. • Electrical, mechanical, procedural and functional specifications. • Data rate, Distances, Physical connector. • Frames, physical addressing. • Synchronization, flow control, error control.

16. The internet layer • Send source packets from any network on the internetwork and have them arrive at the destination independent of the path and networks they took to get there. • Packets, Logical addressing. • Internet Protocol (IP). • Route , routing table, routing protocol.

17. The transport layer • The transport layer deals with the quality-of-service issues of reliability, flow control, and error correction. • Segments, data stream, datagram. • Connection oriented and connectionless. • Transmission control protocol (TCP). • User datagram protocol (UDP). • End-to-end flow control. • Error detection and recovery.

18. The application layer • Handles high-level protocols, issues of representation, encoding, and dialog control.  • The TCP/IP combines all application-related issues into one layer, and assures this data is properly packaged for the next layer. • FTP, HTTP, SMNP, DNS ... • Format of data, data structure, encode … • Dialog control, session management …

19. TCP/IP protocol stack

20. Comparing TCP/IP with OSI

21. Comparing TCP/IP with OSI (cont.) Similarities: • Both have layers. • Both have application layers, though they include very different services. • Both have comparable transport and network layers • Packet-switched technology is assumed. • Networking professionals need to know both.

22. Comparing TCP/IP with OSI (cont.) Differences: • TCP/IP combines the presentation and session layer issues into its application layer. • TCP/IP combines the OSI data link and physical layers into one layer. • TCP/IP appears simpler because it has fewer layers. • Typically networks aren't built on the OSI protocol, even though the OSI model is used as a guide.

23. Physical Topologies Extended Star Bus Ring Hierarchical Star Mesh

24. Physical & Logical Topologies • Physical topologies • Define the actual layout of the wire (media) • Logical topologies • Define how the media is accessed by the hosts

25. Physical Topologies Extended Star Bus Ring Hierarchical Star Mesh

26. Physical Topology: Bus • Single backbone • All hosts directly connected to backbone • Each end of the bus must be properly terminated

27. Physical Topology: Ring • No backbone • A host is directly connected to each of its neighbors

28. Physical Topology: Star • All devices connected to a central point • Center of star is usually a hub or a switch

29. Physical Topology: Extended Star • Connects individual star topologies together. • At the center of the star is a hub or a switch. • Extends the length and size of the network.

30. Physical Topology: Hierarchical • Like the extended star except a computer controls traffic (not a hub or a switch).

31. Physical Topology: Mesh • Each host has its own connection to every other host. • Used in situations where communication must not be interrupted.

32. Technology: Token Ring Token Ring Token Passing

33. Technology: FDDI FDDI Token Passing

34. Technology: Ethernet Ethernet Broadcast

35. Noise (cont.)

36. Noise (cont.) • Too much noise can corrupt a bit, thus destroying the message. • Noise is unavoidable. • Kinds of noise: • Thermal Noise. • Near end cross talk. • AC Power/Reference Ground Noise. • Electromagnetic Interference (EMI). • Radio Frequency Interference (RFI).

37. Signal modulation • AM (amplitude modulation): the amplitude, or height, of a carrier sine wave is varied to carry the message. • FM (frequency modulation): the frequency of the carrier wave is varied to carry the message. • PM (phase modulation): the phase, or beginning and ending points of a given cycle, of the wave is varied to carry the message.

38. Binary encoding • TTL: Transistor-Transistor logic • NRZ-L: Non-Return to Zero-Level • NRZI: Non-Return to Zero-Inverted • NRZ-M: Non-Return to Zero-Mark • Manchester Tx (Transmit) • MLT3: Multi-Level Threshold-3

39. Binary encoding: TTL

40. Binary encoding: NRZ-L, I

41. Binary encoding: Manchester

42. Binary encoding: MLT3

43. Binary encoding: Used • Ethernet: • Manchester Tx+, Tx- • Token-ring: • Differential Manchester • Fast Ethernet: • MLT-3

44. OSI and various LAN standard

45. IEEE • The Institute of Electrical and Electronic Engineers. • LAN standards: • 802.1d: Spanning tree. • 802.2: LLC. • 802.3: MAC ~ Ethernet. • 802.5: MAC ~ Token ring. • 802.11: Wireless LAN.

46. IEEE LAN Standard • Logical Link Control (LLC): Transitions up to the network layer. • Media Access Control (MAC): Transitions down to media.

47. Two Sub-layers WHY ? • LLC serves to communicate upward to Network layer, independent of the specific LAN technology used and Upper layer. • MAC serves to access and communicate downward to the technology-specific Physical layer.

48. MAC address format The remaining six hexadecimal digits comprise the interface serial number. The first six hexadecimal digits, which are administered by the IEEE, identify the manufacturer or vendor.

49. Characteristics • Fiber Distributed Data Interface. • FDDI is popular as a campus backbone technology. • 100 Mbps • Token passing • Dual-ring • Fiber Optic Cable • Total fiber length of 200Km • Station distances up to 2Km

50. FDDI dual-ring (PR and SR)