4.2 Inter-VLAN Routing

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4.2 Inter-VLAN Routing by Mind Map: 4.2 Inter-VLAN Routing

1. 10. Troubleshooting Router Configuration

1.1. Common problem: Assigning the wrong VLAN ID to the subinterface.

1.2. Problem detection command: "show interface"

1.3. Solving problem command: "encapsulation dot1q <vlan_id> interface"

1.4. R1(config)# interface g0/0.10 R1(config-subif)# encapsulation dot1q 10 R1(config-subif)# ip address 172.17.10.1 255.255.255.0 R1(config-subif)# interface g0/0.30 R1(config-subif)# encapsulation dot1q 30 R1(config-subif)# ip address 172.17.30.1 255.255.255.0 R1(config)# interface g0/0 R1(config-subif)# no shutdown

2. Defination of Inter-VLAN Routing

2.1. Layer 2 switches cannot forward traffic between VLANs without the assistance of a router. Process for forwarding network traffic from one VLAN to another, using a router.

3. 4.Switch Configuration

3.1. S1 (config)# vlan 10 S1 (config-vlan)# vlan 30 S1 (config-vlan)# interface f0/11 S1 (config-if)# switchport access vlan 10 S1 (config-if)# interface f0/4 S1 (config-if)# switchport access vlan 10 S1 (config-if)# interface f0/6 S1 (config-if)# switchport access vlan 30 S1 (config-if)# interface f0/5 S1 (config-if)# switchport access vlan 30 S1 (config-if)# end *Mar 20 01:22:56.751: %SYS-5-CONFIG_I: Configured from console by console s1# copy running-config startup-config Destination filename [startup-config]? Building configuration... [OK]

4. 6.Router Subinterface Configuration

4.1. Definition

4.1.1. A sub-interface in a Cisco Router uses the parent physical interface for sending and receiving data.

4.1.2. A subinterface is a virtual interface created by dividing one physical interface into multiple logical interfaces.

4.1.3. Encapsulation is the process of adding control data when it passes through the layered network.

4.1.4. Dot1q encapsulation technique is used when VLAN’s are configured. IEEE 802.1q is simply represented as dot1q.

5. 9.TROUBLESHOOTING SWITCH PORT ISSUES

5.1. Ensure the switch ports connect to the router interface and configure with the correct VLANs.

5.2. Use the switchport access vlan command to correct any erroneous vlan port assignment.

5.3. Ensure the router is connected to the correct switchport

5.4. using router-on-stick ensure that the switchport connected to the router is configure as a trunk link

5.5. use the switchport mode trunk command to to make the switch port a trunk

6. 11.Troubleshooting IP Add & Subnet Mask Configuration Issues

6.1. Use the show IP interface command to verify if the correct IP address is configured in the router.

6.2. Use the show running-config when troubleshooting router

6.3. Subinterface is configured with the correct address for that VLAN.

6.4. Troubleshooting IP Address : Check the configuration. - Check the TCP/IP configuration -Open Command Prompt window and enter the IPCONFIG /ALL command.

7. Layer 3 Switching

7.1. Have Packet-Switching Throughputs in the millions of packets per second (pps). Catalyst Multilayer switches support - Routerd port & Switch Virtual Interface (SVI) High-performance switches able to perform router function (Catalyst 6500 & 4500). Several model require enhanced software for routing protocol features.

8. 12.Inter-VLAN Routing with SVI

8.1. A Switched Virtual Interface (SVI) is a logical interface configured on a layer 3 Switch where SVI has no physical interface and provides Layer 3 processing of packets from all switch ports associated with the VLAN.

8.2. Use to solve problem with lack of router

8.3. only switch with layer 3 can perform SVI

8.4. The default gateway of SVI is it IP address

9. 13. Inter-VLAN Routing with Routed Port

9.1. Routed Port is a physical port acts similarly to an interface on a router.

9.1.1. Function

9.1.1.1. Assign address and enable routing protocols as needed.

9.1.2. Routed Port on a Cisco IOS switch does not support sub-interface.

9.1.3. Not associated with any VLANs.

9.1.4. Routed ports are used in conjunction with SVI’s.

9.1.5. Configuration

9.1.5.1. Use the no switchport command to configure a physical switch port as a routed port.

10. 14.Troubleshooting Layer 3 Switching

10.1. VLANs

10.1.1. VLANs must be defined across all the Switches.

10.1.2. VLANs must be enabled on the trunk ports.

10.1.3. Ports must be in the right VLANs.

10.2. SVIs

10.2.1. SVIs must have the correct IP address or subnet mask

10.2.2. SVIs must be up

10.2.3. SVIs must match with the VLAN number.

10.3. Routing

10.3.1. Routing must enabled.

10.3.2. Each interface or network should be added to the routing protocol.

10.4. Hosts

10.4.1. Hosts must have the correct IP address or subnet mask.

10.4.2. Hosts must have a default gateway associated with an SVI or routed port.

11. 8. Command Verifying Routing

11.1. Access to devices on remote VLANs can be tested using the ping command

11.2. The ping command sends an ICMP echo request to the destination address.

11.3. When a host receives an ICMP echo request, it responds with an ICMP echo reply.

11.4. Tracert is a useful utility for confirming the routed path taken between two devices.

12. 7. Command Subinterface

12.1. R1(config)# interface g0/0.10 R1(config-subif)# encapsulation dot1q 10 R1(config-subif)# ip address 172.17.10.1 255.255.255.0 R1(config-subif)# interface g0/0.30 R1(config-subif)# encapsulation dot1q 30 R1(config-subif)# ip address 172.17.30.1 255.255.255.0 R1(config)# interface g0/0 R1(config-subif)# no shutdown

13. 5. ROUTER INTERFACE CONFIGURTION

13.1. Configuring Gigabit Ethernet Interfaces : 1.interface gigabitethernet slot/port 2. ip address ip-address mask 3. no shutdown 4. exit

13.2. Configuring Wireless LAN Interfaces : 1.interface type number 2. ip address ip-address mask 3. exit

13.3. Configuring a Loopback Interface : 1.interface type number 2. ip address ip-address mask 3. exit

13.4. Interrface ports : 1. interface .gigabitethernet slot/port 2. ip address ip-address mask 3. no shutdown 4. exit

14. 1. Legacy Inter-VLAN Routing

14.1. Routers were used to route between VLANs

14.2. Each VLAN was connected to a different physical router.

14.3. Packets arrive on router through interface, and leave through another.

14.4. Router interfaces were connected to VLANs and had IP address from specific VLAN

14.5. Large network with large number of VLANs required many router interfaces.

14.6. Inter-VLAN routing is to use VLAN trunking and subinterfaces

14.7. VLAN trunking allows a single physical router interface to route traffic for multiple VLANs

14.8. Physical interfaces of router must be connected to trunk link on the adjacent switch

14.9. Subinterfaces are created for unique VLAN

14.10. Each subinterfaces is assigned an IP address specific to its subnet or VLAN

15. 2.Router on a Stick Inter-VLAN Routing

15.1. - The router-on-stick approach uses a different path to route between VLANs.

15.2. - One of the router's physical interfaces is configured as a 802.1Q trunk port so it can understand VLAN tags.

15.3. - Logical subinterfaces are created; one subinterfaces per VLAN.

15.4. - Each subinterface is configured with an IP address from the VLAN it represents.

15.5. - VLAN members (hosts) are configured to use the subinterfaces address as a default gateway.

15.6. - Only one of the router's physical interface is used.

16. 3. MULTILAYER SWITCH INTER-VLAN ROUTING

16.1. - can perform Layer 2 and Layer 3 functions.

16.2. - support dynamic routing and inter-VLAN routing.

16.3. - the multilayer switch must have IP routing enabled.

16.4. - SVI exists for VLAN 1 by default.

16.5. - with a multilayer switch, traffic is routed internal to the switch device.