Inter-Vlan Routing configuration
When you want to establish communication between different VLANs you will need a device that can do routing. You could use an external router with separate physical gateways or sub-interface (router on stick) method but it’s also possible to use a multi-layer switch.
The router must have a physical or logical connection to each VLAN so that it can forward packets between VLANs.
Let’s see the first method router with separate physical gateways:-
- configure the topology as per our diagram and the assign the IP addresses.
- create VLAN 101 sales and VLAN 102 marketing and assign the interfaces to their VLAN as per the diagram
Router(config)#interface fastEthernet 0/0
Router(config-if)#ip address 192.168.10.1 255.255.255.0
Router(config-if)#no shutdown
Router(config-if)#exit
%LINK-5-CHANGED: Interface FastEthernet0/0, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up
Router(config)#interface fastEthernet 0/1
Router(config-if)#ip address 192.168.20.1 255.255.255.0
Router(config-if)#no shutdown
Router(config-if)#exit
%LINK-5-CHANGED: Interface FastEthernet0/1, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up
Router#show ip interface brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 192.168.10.1 YES manual up up
FastEthernet 192.168.20.1 YES manual up up
Switch(config)#vlan 101
Switch(config-vlan)#name sales
Switch(config-vlan)#exit
Switch(config)#vlan 102
Switch(config-vlan)#name marketing
Switch(config-vlan)#exit
Switch(config)#interface range fastEthernet 0/1–2
Switch(config-if-range)#switchport mode access
Switch(config-if-range)#switchport access vlan 101
Switch(config-if-range)#exit
Switch(config)#interface range fastEthernet 0/3–4
Switch(config-if-range)#switchport mode access
Switch(config-if-range)#switchport access vlan 102
Switch(config-if-range)#exit
Switch(config)#interface fastEthernet 0/5
Switch(config-if)#switchport mode access
Switch(config-if)#switchport access vlan 101
Switch(config-if)#exit
Switch(config)#interface fastEthernet 0/6
Switch(config-if)#switchport mode access
Switch(config-if)#switchport access vlan 102
Switch(config-if)#exit
lets see from HOST 4
A router on stick can be used to route between VLANs using either ISL or IEEE 801.1Q as the trunking protocol. its requires sub-interface for each respective VLAN.
NOTE: whatever is your VLAN number its should be exact on sub-interface.
Let see the configuration using sub-interface (router on stick)
Topology:-
- configure the topology as per the diagram and assign the IP addresses
- configure VLAN 101 and VLAN 102
- assign the port to their respective VLANs
- configure sub-interfaces on router fast Ethernet 0/0 assign IP address as per the topology
- ensure the connectivity between VLAN 101 and VLAN 102, make sure HOST 1 (VLAN 101) IS able to ping HOST 4 (VLAN 102).
Switch(config)#vlan 101
Switch(config-vlan)#name sales
Switch(config-vlan)#exit
Switch(config)#vlan 102
Switch(config-vlan)#name marketing
Switch(config-vlan)#exit
Switch(config)#interface range fastEthernet 0/1–2
Switch(config-if-range)#switchport mode access
Switch(config-if-range)#switchport access vlan 101
Switch(config-if-range)#exit
Switch(config)#interface range fastEthernet 0/3–4
Switch(config-if-range)#switchport mode access
Switch(config-if-range)#switchport access vlan 102
Switch(config-if-range)#exit
Switch(config)#interface fastEthernet 0/5
Switch(config-if)#switchport trunk encapsulation dot1q
Switch(config-if)#switchport trunk allowed vlan 101,102
Switch(config-if)#exit
Router(config)#interface fastEthernet 0/0
Router(config-if)#no shutdown
Router(config-if)#exit
Router(config)#interface fastEthernet 0/0.101
Router(config-subif)#encapsulation dot1Q 101
Router(config-subif)#ip address 192.168.10.1 255.255.255.0
Router(config-subif)#exit
Router(config)#interface fastEthernet 0/0.102
Router(config-subif)#encapsulation dot1Q 102
Router(config-subif)#ip address 192.168.20.1 255.255.255.0
Router(config-subif)#exit
%LINK-5-CHANGED: Interface FastEthernet0/0.102, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0.102, changed state to up
Router#show ip interface brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 unassigned YES manual up up
FastEthernet0/0.101 192.168.10.1 YES manual up up
FastEthernet0/0.102 192.168.20.1 YES manual up up
let see the third method , inter-VLAN routing using multi-layer switch
switch virtual interface (SVI).
NOTE: to enable routing on multi-layer switch is command use IP ROUTING.
Topology:-
Goal:
- configure the topology as per the diagram and assign the IP address as per the topology
- configure VLAN 111, VLAN 122 and assign the port into their VLANs respectively
- configure the IP address on multilayer switch
Switch(config)#vlan 111
Switch(config-vlan)#name sales
Switch(config-vlan)#exit
Switch(config)#vlan 122
Switch(config-vlan)#name marketing
Switch(config-vlan)#exit
Switch(config)#interface range fastEthernet 0/1–2
Switch(config-if-range)#switchport access vlan 111
Switch(config-if-range)#exit
Switch(config)#interface range fastEthernet 0/3–4
Switch(config-if-range)#switchport mode access
Switch(config-if-range)#switchport access vlan 122
Switch(config-if-range)#exit
Switch(config)#ip routing
Switch(config)#interface vlan 111
Switch(config-if)#ip address 192.168.10.1 255.255.255.0
Switch(config-if)#no shutdown
%LINK-5-CHANGED: Interface Vlan111, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan111, changed state to up
Switch(config-if)#exit
Switch(config)#interface vlan 122
Switch(config-if)#ip address 192.168.20.1 255.255.255.0
Switch(config-if)#no shutdown
Switch(config-if)#exit
Switch(config)#end
%LINK-5-CHANGED: Interface Vlan122, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan122, changed state to up
Switch#show ip interface brief
Interface IP-Address OK? Method Status Protocol
Vlan111 192.168.10.1 YES manual up up
Vlan122 192.168.20.1 YES manual up up
let see the connectivity between both the VLANs.
Originally published at https://www.internetworks.in.
