1. The University of Bolton School of Games Computing & Creative Technologies LCT2516 Network Architecture CCNA Exploration LAN Switching and Wireless Chapter 3 – Virtual Local Area Networks (VLANs) Martin Stanhope m.stanhope@bolton.ac.uk 1

2. Overview VLANsTrunking Configuring VLANs & Trunks Troubleshooting VLANs & Trunks Chapter 3 Virtual Local Area Networks 2

3. Chapter sections 3.0 Introduction 3.1 Introducing VLANs 3.2 VLAN trunking 3.3 Configure VLANs and Trunks 3.4 Troubleshooting VLANs and Trunks 3.5 Labs 3.6 Summary 3.7 Quiz 3

4. Example – Multiport switch 4 fa 0/1 v1 fa 0/2 v1 fa 0/3 v1 fa 0/4 v1 fa 0/5 v1 fa 0/6 v1 fa 0/7 v1 All ports belong to VLAN1 by default (abbreviated in the above as v1)

5. Create 2 new vlans and assign ports to them 5 fa 0/1 v1 fa 0/2 v2 fa 0/3 v2 fa 0/4 v3 fa 0/5 v3 fa 0/6 v1 fa 0/7 v1 VLANs are only created on switches. Switch ports are then assigned to the VLANs PCs are then attached to the switch ports. The PCs become members of the VLANs due to the ports they a wired to. This is STATIC (port-centric) VLAN membership.

6. CLI commands to create the two new VLANs S1# configure terminal S1(config)# vlan 2 S1(config)# name students S1(config)# vlan 3 S1(config)# name staff S1(config)# end 6

7. Assign switch ports to the new VLANs S1# configure terminal S1(config)# interface fa0/2 S1(config-if)# switchport mode access S1(config-if)# switchport access vlan 2 S1(config)# interface fa0/3 S1(config-if)# switchport mode access S1(config-if)# switchport access vlan 2 S1(config)# interface fa0/4 S1(config-if)# switchport mode access S1(config-if)# switchport access vlan 3 S1(config)# interface fa0/5 S1(config-if)# switchport mode access S1(config-if)# switchport access vlan 3 7

8. Attach PCs to the ports and assign appropriate IP addresses 8 fa 0/1 v1 fa 0/2 v2 fa 0/3 v2 fa 0/4 v3 fa 0/5 v3 fa 0/6 v1 fa 0/7 v1 192.168.1.10 192.168.3.10192.168.3.11 192.168.2.10192.168.2.11

9. Linking VLANs across 2 switches (no trunks used) 9 VLAN1 VLAN2 VLAN3 Colour key... PCs can only communicate with PCs in the same VLAN. Notice how ports and cables are required to link the VLANs on both switches Inter VLAN communications will require a router.

10. Linking VLANs across 2 switches using a trunk link 10 T T VLAN1 VLAN2 VLAN3 Colour key... One port on each switch is configured as a TRUNK port. A trunk link allows traffic from any VLAN to cross it. Trunking reduces the number of ports and cables required to allow traffic from multiple VLANs to move between the switches. Frames are tagged with an ID representing their source VLAN by the originating switch so they be delivered to the corresponding VLAN at the other end of the trunk link. PCs can only communicate with other PCs in the same VLAN. Inter VLAN communications requires router.

11. Creating trunk ports Configure an 802.1q trunk on Switch 1 port fa0/6 S1(config)# interface fa0/6 S1(config)# switchport mode trunk S1(config)# switchport trunk native vlan 1 S1(config)# end Configure an 802.1q trunk on Switch 2 port fa0/6 S2(config)# interface fa0/6 S2(config)# switchport mode trunk S2(config)# switchport trunk native vlan 1 S2(config)# end 11

12. Inter-VLAN routing (no trunks) 12 VLAN1VLAN2VLAN3 Colour key... Router Three router ports are required as there are 3 networks (VLANs) to interconnect

13. Inter-VLAN routing using trunks 13 T T VLAN1VLAN2VLAN3 Colour key... T Router How can 3 networks, VLAN 1, 2 and 3 be interlinked using just 1 router port?

14. Inter-VLAN routing using trunks. Router subinterfaces. 14 T T VLAN1VLAN2VLAN3 Colour key... T Router A router physical interface e.g., fa0/0, can be configured to act as multiple ‘virtual’ subinterfaces identified using the following naming convention. One interface for each VLAN... fa0/0.1, fa0/0.2, fa0/0.3 etc.

15. Configuration of router subinterfaces See chapter 4 15

16. VLAN setup showing full configuration information 16 T T VLAN1 192.168.1.0/24VLAN2 192.168.2.0/24VLAN3 192.168.3.0/24 Colour key... T Router fa0/0... fa0/0.1 VLAN 1 interface 192.168.1.1/24... fa0/0.2 VLAN 2 interface 192.168.2.1/24... fa0/0.3 VLAN 3 interface 192.168.3.1/24 Switch 1 management info: IP = 192.168.1.2/24 (a valid VLAN1 address) DG = 192.168.1.1/24 (i.e. VLAN 1 interface address) Switch 2 management info: IP = 192.168.1.3/24 (a valid VLAN1 address) DG = 192.168.1.1/24 (i.e. VLAN 1 interface address)

17. Class B subnetting example used in activities Class B subnetting –172.17.0.0/16 (Network section, host section) –172.17.0.0/24 (Network, subnet, host sections) 172.17.1.0/24 172.17.2.0/24 –....The following 3 class B subnets are used in some of the Cisco activities and are used in VLANs that have been numbered 10, 20 and 30 for ease of reference... –VLAN 10 172.17.10.0/24 (Hosts 172.17.10.1/24 to 172.17.10.254/24) –VLAN 20 172.17.20.0/24 (Hosts 172.17.20.1/24 to 172.17.20.254/24) –VLAN 30 172.17.30.0/24 (Hosts 172.17.30.1/24 to 172.17.30.254/24) 17

18. Class A subnetting example used Cisco tests Class A subnetting –10.0.0.0/8 (Network section, host section) –10.0.0.0/16 (Network, subnet, host section) –10.0.0.0/24 (Network, subnet, host section) –These two class A subnet are often seen in Cisco tests... –VLAN 2, 10.1.2.0/24 (Hosts 10.1.2.1/24 to 10.1.2.254/24) –VLAN 3, 10.1.3.0/24 (Hosts 10.1.3.1/24 to 10.1.3.254/24) 18