1. Sybex CCNA 640-802 Chapter 8: Layer-2 Switching Instructor & Todd Lammle

2. Chapter 8 Objectives The CCNA Topics Covered in this chapter include: What is layer-2 switching Switching services Bridges vs. LAN switching Three switch functions MAC table Switching loops Spanning-Tree Protocol (STP) 2

3. Layer 2 Switching Purposes for using switching –Breaks up collision domains –Cost-effective, resilient internetwork Purpose for Spanning-Tree Protocol (STP) –Stops loops in layer 2 switched networks

4. Before Layer 2 Switching

5. Switched LANs

6. Typical Switched Designs

7. One link to the server!

8. Switching Services Layer 2 switching provides: –Hardware-based bridging (ASIC) –Wire speed –Low latency –Low cost

9. Limitations of Layer 2 Switching Must break up the collision domains correctly. Make sure that users spend 80 percent of their time on the local segment. Switches do not break up broadcast domains by default.

10. Bridging vs. LAN switching

11. Three Switch Functions at Layer-2

12. Empty MAC table

13. How Switches Learn Hosts’ Locations

14. Switching Loops

15. Switching Loop Problems

16. Spanning-Tree Protocol (STP) Solves Switching loops at layer 2 STP Root Bridge BPDU Bridge ID Nonroot Bridge Root port Designated port Port cost Nondesignated port Forwarding port Block port

17. Spanning-Tree Operations Selecting the root bridge Selecting the designated port

18. Switching Loops

19. Spanning-Tree Port States Blocking Listening Forwarding Disabled

20. Spanning-Tree Example

21. Written Labs and Review Questions –Open your books and go through all the written labs and the review questions. –Review the answers in class. 21