1. Chabot College ET 99.09 Cisco Semester 3 Chapter 3 VLANs M. McGregor, Los Medanos College, Pittsburg, CA

2. Chabot College Introduction to VLANs

3. Chabot College What is a VLAN?

4. Chabot College Why create VLANs?

5. Chabot College Switches are the core of VLANs

6. Chabot College VLAN Switching and Filtering Each switch has the intelligence to make filtering and forwarding decisions by frame, based on VLAN metrics defined by network managers, and to communicate this information to other switches and routers within the network.

7. Chabot College Frame filtering and tagging The most common approaches for logically grouping users into distinct VLANs are: frame filtering frame tagging

8. Chabot College Frame Filtering

9. Chabot College Tradeoffs with frame filtering Filter-based VLANs do not scale well because each frame has to be referenced to a lookup table. The IEEE 802 committee has adopted frame tagging as the standard because it is more scalable.

10. Chabot College IEEE 802 VLAN Standardization

11. Chabot College Frame Tagging

12. Chabot College VLAN Flexibility

13. Chabot College Problems with broadcasts

14. Chabot College Problems with broadcasts When no routers are placed between switches, broadcasts (Layer 2 transmissions) are sent to every switched port. This is commonly referred to as a “flat” network where there is one broadcast domain across the entire network

15. Chabot College VLANs can control broadcasts

16. Chabot College VLANs can provide security

17. Chabot College VLANs provide flexibility

18. Chabot College Where are the routers? Layer 3 communication, either embedded in the switch or provided externally, is an integral part of any high-performance switching architecture.

19. Chabot College What are hubs good for?

20. Chabot College Leveraging your investment

21. Chabot College Port-Centric VLANs

22. Chabot College Port-centric VLANs VLAN Membership by port maximizes forwarding performance because:  Users are assigned by port.  VLANs are easily administered  Maximizes security between VLANs  Packets do not “leak” into other domains  VLANs and membership are easily controlled across network

23. Chabot College Static VLANs

24. Chabot College Dynamic VLANs Dynamic VLANs are ports on a switch that can automatically determine their VLAN assignments.

25. Chabot College VLANs across backbones

26. Chabot College VLANs across backbones Fast Ethernet - ISL (Inter-Switch Link) FDDI - IEEE 802.10 ATM - LAN Emulation (LANE)

27. Chabot College VTP - VLAN Trunk Protocol VTP Domain VTP Configuration revision number VLAN IDs (ISL) Emulated LAN names (ATM) 802.10 SAID values (FDDI) MTU Frame format VLAN configuration