1. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Year 2 - Chapter 16/Cisco 4 - Module 9 CCNA Certification Exam Review By Your Name

2. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual OSI Model

3. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Understanding the Physical Layer Hubs MAUs Repeaters Transceivers

4. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Layer 1 Versus Layer 2 Layer 1 –Cannot communicate with the upper-layer protocols –Cannot name or identify computers –Can describe only streams of bits –Cannot decide which computer will transmit data from a group that are all trying to transmit at the same time Layer 2 –Communicates with upper- layer protocols using Logical Link Control (LLC) –Provides an addressing (or naming) process –Uses framing to organize or group the bits –Uses a system called Media Access Control (MAC) Layer 2 to control transmissions Layer 2 deals with the limitations of Layer 1.

5. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Comparing LAN Standards

6. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual OSI Layer 1 and 2 Together Are the Access Protocols These are the delivery system protocols. Independent of: –Network OS –Upper-level protocols TCP/IP, IPX/SPX Sometimes called: –Access methods –Access protocols –Access technologies –Media access –LAN protocols –WAN protocols Ethernet, Fast Ethernet, Gigabit Ethernet, Token Ring, FDDI, Frame Relay, ATM, PPP, HDLC, and so on

7. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Creating Subnets How to Create a Subnet Subnet Planning

8. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual LAN Switching Full-Duplex and Half-Duplex Ethernet Operations Configuring Both Ends Configuring a Router Mismatch Between Two Switches

9. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual LANs and Devices

10. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual WANs and Devices

11. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Full-Duplex and Half-Duplex Half-Duplex Shared media Full-Duplex Separate media 10BaseT, 100BaseX, 1000BaseX

12. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Ethernet Frame The MAC Address Hub Operation The Switch Operation Microsegmentation of a Network Switches and Buffers A Flat Network LAN Segmentation Using Routers ARP Request/Reply

13. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual The Data Link Layer 802.2 Logical Link Control 802.3 Ethernet 802.5 Token Ring

14. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual MAC Addresses

15. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Token Ring Frame Format

16. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual FDDI Frame Format

17. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual OSI Versus Ethernet Standards

18. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Ethernet Family Tree

19. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Ethernet and IEEE 802.3 Frame Formats Type (Ethernet) Specifies the upper-layer protocol to receive the data after Ethernet processing. Length (IEEE 802.3) The number of bytes of data that follows this field. Data (Ethernet) Ethernet version 2 does not specify any padding. Data (IEEE 802.3) Upper-layer protocol, is defined (LLC) in the data portion of the frame. If data is insufficient to fill the frame to the minimum 64-byte size, padding bytes are added. Preamble — Alternating pattern of 1s and 0s (up to 31 pairs) tells receiving station that a data frame is coming.

20. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual TCP/IP Protocol Graph

21. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual TCP Segment Format

22. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual UDP Segment Format

23. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Port Numbers

24. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Switching Overview LAN Switch Latency Layer 2 and Layer 3 Switching How a LAN Switch Learns Addresses The Benefits of Switching Symmetric and Asymmetric Switching Memory Buffering Two Switching Methods VLANs

25. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Switching — The process of taking an incoming frame from one interface and delivering it out through another interface Layer 2 Switching –Switching based on MAC destination address. –Builds switching table by “learning” host addresses from source addresses of incoming packets. –Unknown destination addresses are flooded out other ports. –Broadcast packets are flooded out other ports. Layer 3 Switching –Switching based on network layer destination address. –Builds route table of networks from configured entries and routes shared by neighbor routers. –Unknown network packets are discarded (if no default entry). –Broadcast packets are discarded. Layer 2 and Layer 3 Switching

26. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Symmetric and Asymmetric Switching Cut-Through and Store-and-Forward LAN Switching The Benefits of Virtual LANs Why Use Port-Centric VLANs? Routing and VLANs VLAN Tagging

27. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Symmetric Switching

28. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Asymmetric Switching

29. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Memory Buffering Port-based memory buffering –Packets are stored in queues that are linked to specific incoming ports. –Possible for a single packet to block all other packets because its destination port is busy (even if the other packets could be delivered). Shared memory buffering –All packets use a common memory buffer. –Packets in the buffer are then linked (mapped) dynamically to the appropriate destination port. –Helps balance between 10 and 100 Mbps ports.

30. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Two Switching Methods Store-and-forward — Entire frame is checked before forwarding. –Highest latency –Highest error detection Cut-through — Only part of frame is checked before forwarding. –Fast-forward: checks only destination address Lowest latency No error detection –Fragment-free: checks destination and that size is at least 64 bytes Medium latency Catches (runts) — Collision fragments

31. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Switching Methods Compared

32. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Overview of Spanning-Tree Protocol

33. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Redundancy and Loops Newer switched networks include redundant links to increase reliability and reduce single points of failure. With that comes the potential for data loops.

34. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Spanning-Tree Protocol Multiple paths to a destination provide redundancy and make a network robust. STP uses spanning-tree algorithm (STA). STP is a switched Ethernet network solution to deal with potential for data loops introduced by multiple paths. –Routers can manage multiple paths to avoid loops. –Hub networks would stop immediately with multiple paths. STP detects potential loops and “blocks” one path. –Blocked path can be quickly activated if other link fails. –Uses Layer 2 BPDUs (bridge protocol data units) to communicate between switches and detect potential loops.

35. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Blocking –No frames forwarded, BPDUs heard Listening –No frames forwarded, listening for frames Learning –No frames forwarded, learning addresses Forwarding –Frames forwarded, learning addresses Disabled –No frames forwarded, no BPDUs heard Ports typically progress from Blocking > Listening > Learning > Forwarding. The Five Spanning-Tree Protocol States

36. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual LAN Segmentation

37. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Collision Domains

38. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual WAN Physical Layer Standards

39. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual WAN Data Link Layer Protocols

40. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual WAN Data Link Layer Protocols

41. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Connection-Oriented Service

42. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual WAN Encapsulation Formats (PPP)

43. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual WAN Encapsulation Formats (HDLC)

44. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual WAN Link Options

45. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Point-to-Point Links Dedicated Lines

46. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Point-to-Point Links Leased Lines

47. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Packet-Switched Connections

48. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Frame Relay

49. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Circuit-Switched Connections

50. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual Dial-on-Demand Routing

51. www.ciscopress.com Copyright 2002Cisco Press: CCNA Instructor’s Manual ISDN