In this post , we share a step by step tested and working command line procedure for enabling Inter VLAN routing on a Cisco Layer 3 or L3 switch using Switch Virtual Interface (SVI). In this simple example we cover the following topics- Create VLAN 100 , assign a IP to it (SVI) , connect a host 'A' to VLAN 100
- Create VLAN 200 , assign a IP to it (SVI), connect a host 'B' to VLAN 200
- Enable Inter VLAN routing so that host A may reach Host B
Create VLAN 100 , assign a IP to it (SVI) , connect a host 'A' to VLAN 100
Switch1 # config terminal
Switch1(config)#int
vlan 100
Switch1(config-if)#description VLAN100
Switch1(config-if)#no
shut
Switch1(config-if)#ip
address 10.1.1.1 255.255.255.0
Switch1(config-if)# ^Z
Switch1(config)#interface
f1/0/1
Switch1(config-if)#switch
access vlan 100
Switch1(config-if)#no
shut
With the above steps , VLAN100 will be created and port f1/0/1 is assigned to VLAN100. Connect Host A to this port and assign a IP of range 10.1.1.X say for example 10.1.1.2.
Verify whether Host A is able to reach the VLAN virtual interface 10.1.1.1 using ping command. Output should show a response as below
Host A Terminal # ping 10.1.1.1
Pinging 10.1.1.1 with 32 bytes of data:
Reply from 10.1.1.1: bytes=32 time=1ms TTL=127
Reply from 10.1.1.1: bytes=32 time=1ms TTL=127
Switch1 # config terminal
Switch1(config)#int vlan 200
Switch1(config-if)#description VLAN200
Switch1(config-if)#no shut
Switch1(config-if)#ip address 20.1.1.1 255.255.255.0
Switch1(config-if)# ^Z
Switch1(config)#interface f1/0/2
Switch1(config-if)#switch access vlan 200
Switch1(config-if)#no shut
With the above steps , VLAN200 will be created and port f1/0/2 is assigned to VLAN200. Connect Host B to this port and assign a IP of range 20.1.1.X say for example 20.1.1.2.
Verify whether Host B is able to reach the VLAN virtual interface 20.1.1.1 using ping command. Output should show a response as below
Host B Terminal # ping 20.1.1.1
Pinging 20.1.1.1 with 32 bytes of data:
Reply from 20.1.1.1: bytes=32 time=1ms TTL=127
Reply from 20.1.1.1: bytes=32 time=1ms TTL=127
Host B Terminal # ping 10.1.1.2
Pinging 10.1.1.2 with 32 bytes of data:
Request timed out
Request timed out
Enabling Inter VLAN routing
Well this is a very simple step. Just enable the IP routing option on your L3 switch . Some switches may require reboot to load the configuration . In such cases issue a reload command.
Verify whether IP routing feature is enabled , when disabled - status would be as below
Switch1#show
ip route
Default
gateway is not set
Host Gateway Last Use Total Uses
Interface
ICMP
redirect cache is empty
Switch1 # config terminal
Switch1(config)# ip routing
Switch1(config-if)# ^Z
Switch1 # reload
Once the switch reboots , verify the routing status and whether either hosts may reach the other end using ping command.
Switch1#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
10.0.0.0/24 is subnetted, 1 subnets
20.0.0.0/24 is subnetted, 1 subnets
C 10.1.1.0 is directly connected, Vlan100
C 20.1.1.0 is directly connected, Vlan200
Host A Terminal # ping 20.1.1.2
Pinging 20.1.1.2 with 32 bytes of data:
Reply from 20.1.1.2: bytes=32 time=1ms TTL=127
Reply from 20.1.1.2: bytes=32 time=1ms TTL=127
Host B Terminal # ping 10.1.1.2
Pinging 10.1.1.2 with 32 bytes of data:
Reply from 10.1.1.2: bytes=32 time=1ms TTL=127
Reply from 10.1.1.2: bytes=32 time=1ms TTL=127
Hope this helps to some beginners.
