1. 1 Large-scale (Campus) Lan design (Part II)  VLANs  Hierarchical LAN design

2. 2 Virtual LANs (VLANs)  VLANs consist of end systems that are members of a single logical broadcast domain.  A VLAN has no physical proximity constraints for the broadcast domain  A VLAN can span various pieces of network equipment that support VLAN trunking protocols between them  Without a router, hosts in 1 VLAN can’t communicate with hosts in another VLAN

3. 3 Single-switch VLANs

4. 4 VLAN Benefits  VLANs break networks into smaller broadcast domains  VLANs provide security  Easier network management  Well-behaved VLANs usually follow 80/20 network design rule

5. 5 VLAN Example

6. 6 VLAN Trunking  Trunk – high-speed connection between internetworking devices  Switches use Trunking protocol to exchange information about VLAN configuration (e.g. IEEE 802.1Q, Cisco’s ISL)  With trunking, tags are added to all the frames traveling on the trunk

7. 7 VLANs are shared through trunks

8. 8 VLAN Implementation  By port – each port must belong to only 1 VLAN  By protocol – single port can support more than 1 VLAN  By a user-defined value – e.g. MAC address

9. Single switch VLANs 9

10. Multi-switch VLANs 10

11. 11 Backbone  Traditional  Collapsed

12. 12 Redundancy in the Backbone

13. 13 Distributed backbone (multiple collapse points)

14. 14 Distributed backbone (multiple collapse points)

15. 15 Hierarchical Design  Access  Distribution  Core

16. 16 Hierarchical Design

17. 17 Central Routing

18. 18 Distributed Routing

19. 19 Small campus

20. 20 Medium campus

21. 21 Large campus