Inter VLAN routing with CEF - GNS3

Place your GNS3 router as below, i use Cisco 3640 with additional slot NM-16ESW to act as a layer 3 switch

for the layer 2 switch, set the properties as below

port 11 access port for vlan 100
port 12 access port for vlan 200
port 13 trunk, dot1q encapsulation

create vlan 100 and 200 on router


Router>en
Router#vlan da
Router(vlan)#vla 100

repeat the same to create vlan 200

enable inter vlan routing

Router(config)#ip routing
Router(config)#

configure the vlan interface(routed interface for that vlan), vlan 1 is for management


interface Vlan1
 ip address 172.16.1.1 255.255.255.0
!
interface Vlan100
 ip address 192.168.100.1 255.255.255.0
!
interface Vlan200
 ip address 192.168.200.1 255.255.255.0

configure trunking

*always remember to no shutdown on interface, by default, like router, the interface is shutdown, unlike switch. Once the interface is up, trunk will work then the int vlan will be up

Router(config)#int fa 0/1

Router(config-if)#switchport trun encap dot1 //set the encapsulation

Router(config-if)#switchport mo trunk //set to trunk unconditionally

Now you should be able to ping from host on vlan 100 and 200 to the 192.168.100.1 and 192.168.200.1


VPCS 2 >ping 192.168.100.1
192.168.100.1 icmp_seq=1 time=5.188 ms
192.168.100.1 icmp_seq=2 time=3.645 ms
192.168.100.1 icmp_seq=3 time=3.547 ms
192.168.100.1 icmp_seq=4 time=20.745 ms
192.168.100.1 icmp_seq=5 time=34.342 ms


VPCS 2 >ping 192.168.200.1
192.168.200.1 icmp_seq=1 time=3.296 ms
192.168.200.1 icmp_seq=2 time=12.255 ms
192.168.200.1 icmp_seq=3 time=4.190 ms
192.168.200.1 icmp_seq=4 time=2.341 ms
192.168.200.1 icmp_seq=5 time=17.070 ms

you can use this command to check on the CEF status

show ip int vlan 100


Router#sh ip int vlan 100
Vlan100 is up, line protocol is up
  Internet address is 192.168.100.1/24
  Broadcast address is 255.255.255.255
  Address determined by non-volatile memory
  MTU is 1500 bytes
  Helper address is not set
  Directed broadcast forwarding is disabled
  Outgoing access list is not set
  Inbound  access list is not set
  Proxy ARP is enabled
  Local Proxy ARP is disabled
  Security level is default
  Split horizon is enabled
  ICMP redirects are always sent
  ICMP unreachables are always sent
  ICMP mask replies are never sent
  IP fast switching is enabled
  IP fast switching on the same interface is disabled
  IP Flow switching is disabled
  IP CEF switching is enabled
  IP CEF Fast switching turbo vector
  IP multicast fast switching is enabled
  IP multicast distributed fast switching is disabled
  IP route-cache flags are Fast, CEF
  Router Discovery is disabled
  IP output packet accounting is disabled
  IP access violation accounting is disabled
  TCP/IP header compression is disabled
  RTP/IP header compression is disabled
  Policy routing is disabled
  Network address translation is disabled
  BGP Policy Mapping is disabled
  WCCP Redirect outbound is disabled
  WCCP Redirect inbound is disabled
  WCCP Redirect exclude is disabled

show ip cef summary

show ip cef

sh ip route to show all the connected subnet

running config for router


Router#sh run
Building configuration...


Current configuration : 1064 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Router
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
!
!
ip cef
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
interface FastEthernet0/0
!
interface FastEthernet0/1
 switchport mode trunk
!
interface FastEthernet0/2
!
interface FastEthernet0/3
!
interface FastEthernet0/4
!
interface FastEthernet0/5
!
interface FastEthernet0/6
!
interface FastEthernet0/7
!
interface FastEthernet0/8
!
interface FastEthernet0/9
!
interface FastEthernet0/10
!
interface FastEthernet0/11
!
interface FastEthernet0/12
!
interface FastEthernet0/13
!
interface FastEthernet0/14
!
interface FastEthernet0/15
!
interface Vlan1
 ip address 172.16.1.1 255.255.255.0
!
interface Vlan100
 ip address 192.168.100.1 255.255.255.0
!
interface Vlan200
 ip address 192.168.200.1 255.255.255.0
!
ip http server
no ip http secure-server
!
!
!
!
!
!
control-plane
!
!
!
!
!
!
!
!
!
!
line con 0
line aux 0
line vty 0 4
 login
!
!
end