1. Instructor & Todd Lammle Sybex CCNA 640-802 Chapter 9: VLAN’s 1

2. Chapter 9 Objectives The CCNA Topics Covered in this chapter include: What is a VLAN? VLAN Memberships VLAN links Frame tagging VTP Trunking Configuring VLANs Inter-VLAN Communication Configuration examples 2 2

3. Virtual LANs (VLANs) VLAN - Definition: –A logical grouping of network users and resources –connected to –administratively defined ports on a switch. –gives you: –Smaller “broadcast domains” –Organized by: –Location (e.g., the 4 th floor) –Function e.g., IT techs, or a group with high security needs) –Department (e.g., the accounting department) –Application or protocol (e.g., everyone running AppleTalk – maybe in the Graphics dept.) 3

4. Switches 4

5. Features of VLANs Simplify network management: –You control each port in a VLAN, and each switch can contain a number of VLANs, so you can no longer just cable into a switch and see all of the traffic on that switch. –Also, a VLAN can be configured with a number of reporting functions, for example, report any attempt at unauthorized access Provides a level of security over a flat network: –“Flat” as in a network that is one, large broadcast domain –Security: see ff Flexibility and Scalability: –With the old hub & switch networks, you could run out of space on a switch or in an office, but with VLANs, you just add a new user to an existing VLAN and go. Book, pp 555 ff, 5

6. Features: Broadcast Control Broadcasts occur in every protocol –but how often they occur depends upon 3 things: The type of protocol (some are worse than others) The application(s) running on the internetwork (ditto) How these services are used 6

7. Flat Network Structure 7

8. Security Flat network problems –A flat internetwork’s security used to be tackled by connecting hubs and switches together with routers. –So it was the router’s job to maintain security. This was pretty ineffective for several reasons. First, anyone connecting to the physical network could access the network resources on that physical LAN. Second, all anyone had to do to observe any and all traffic in that network was to plug a network analyzer into the hub VLANs –If you create multiple broadcast groups, you have total control over each port and user! –So the days when anyone could just plug their workstations into any switch port and gain access to network resources are history because now you get to control each port, plus whatever resources that port can access. 8

9. Flexibility & Scalability Layer-2 switches only read frames –Can cause a switch to forward all broadcasts VLANs –Essentially create broadcast domains Greatly reduces broadcast traffic Ability to add wanted users to a VLAN regardless of their physical location Additional VLANs can be created when network growth consumes more bandwidth 9

10. Switched Network 10

11. Physical LANs Connected To A Router 11

12. VLANs Remove Physical Boundary 12

13. VLAN Memberships Static VLANs –Typical method of creating VLANs –Most secure A switch port assigned to a VLAN always maintains that assignment until changed Dynamic VLANs –Node assignment to a VLAN is automatic MAC addresses, protocols, network addresses, etc –VLAN Management Policy Server (VMPS) MAC address database for dynamic assignments MAC-address to VLAN mapping Book, pg 558 ff: 13

14. Identifying VLANs Access links –A link that is part of only one VLAN Trunk links –Carries multiple VLANs 14

15. Identifying VLANs (cont.) 15

16. Frame Tagging Frame Tagging: A means of keeping track of users & frames as they travel the switch fabric & VLANs –User-defined ID assigned to each frame –VLAN ID is removed before exiting trunked links & access links 16

17. VLAN ID Methods Inter-Switch Link (ISL) –Cisco proprietary (becoming obsolete) –FastEthernet & Gibabit Ethernet only IEEE 802.1q –Must use if trunking between Cisco & non- Cisco switch 17

18. Inter-Switch Link (ISL) Protocol ISL: A means of explicitly tagging VLAN information onto an Ethernet frame –Allows VLANs to be multiplexed over a trunk line –Cisco proprietary –External tagging process 18

19. VLAN Trunk Protocol (VTP) Purpose: to manage all configured VLANs across a switch internetwork & maintain consistency –Allows an administrator to add, delete, & rename VLANs 19

20. VTP Benefits Benefits –Consistent configuration across all switches in the network –Permits trunking over mixed networks, such as Ethernet to ATM LANE or even FDDI –Accurate tracking and monitoring of VLANs –Dynamic reporting of added VLANs to all switches in the VTP domain –Plug-and-Play A VTP server must be created to manage VLANs 20

21. VTP Modes 21

22. VTP Modes of Operation Server –Default for all Catalyst switches –Minimum one server for a VTP domain Client –Receives information + sends/receives updates –Cannot make any changes Transparent –Does not participate in a VTP domain but forwards VTP advertisements –Can add/delete VLANs –Locally significant 22

23. Router with Individual VLAN associations 23

24. Routing Between VLANs 24

25. Configuring VLANs Creating VLANs Assigning Switch Ports to VLANs Configuring Trunk Ports Configuring Inter-VLAN routing 25

26. Configuring VTP Default: Switches are configured to be VTP servers 26

27. InterVLAN Configuration Example Switch#config t Switch(config)#int fa0/1 Switch(config-if)# switchport mode trunk 27

28. Example 2 Switch#config t Switch(config)#int f0/1 Switch(config-if)#switchport mode trunk Switch(config-if)#int f0/2 Switch(config-if)#switchport access vlan 1 Router#config t Router(config)#int f0/0 Router(config-if)#no ip address Router(config-if)#no shutdown Router(config-if)#int f0/0.1 Router(config-subif)#encapsulation dot1q 1 Router(config-subif)#ip address 192.168.10.17 255.255.255.240 28

29. Example 3 29

30. Example 4 30

31. Configuring Switching In Our Sample Internetwork 31

32. 2950C 32

33. 2950B 33

34. Setting Up Trunking 34

35. Inter-VLAN communication The End 35