Virtual Routing and Forwarding

• Function as isolated virtual router instances inside a physical router
• VRF-lite: VRF without MP-BGP or MPLS

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Configuration Example

In this topology, VRF separates customers Gym and School network traffic. Each customer has isolated routing even though they use the same IP addresses.

ISP-1

ip vrf GYM                                                //Create a virtual router instance named GYM
ip vrf SCHOOL                                             //Create a virtual router instance named SCHOOL

interface Ethernet 0/1
 description GYM
 ip vrf forwarding GYM                                    //Assign this interface to virtual router GYM
 ip address 61.201.1.1 255.255.255.248

interface Ethernet 0/0.11
 description GYM
 encapsulation dot1q 11
 ip vrf forwarding GYM                                    //Assign this sub-interface to virtual router GYM
 ip address 10.1.1.1 255.255.255.252

interface Ethernet 0/0.12
 description SCHOOL
 encapsulation dot1q 12
 ip vrf forwarding SCHOOL                                 //Assign this sub-interface to virtual router SCHOOL
 ip address 10.1.1.1 255.255.255.252

router ospf 11 vrf GYM                                    //An OSPF process 11 for virtual router GYM
 network 10.1.1.0 0.0.0.255 area 1
 network 61.201.1.0 0.0.0.255 area 1

router ospf 22 vrf SCHOOL                                 //An OSPF process 22 for virtual router SCHOOL
 network 10.1.1.0 0.0.0.255 area 1
 network 61.201.1.0 0.0.0.255 area 1

ISP-2

ip vrf GYM
ip vrf SCHOOL

interface Ethernet 0/1
 description GYM
 ip vrf forwarding GYM
 ip address 61.202.2.1 255.255.255.248

interface Ethernet 0/2
 description SCHOOL
 ip vrf forwarding SCHOOL
 ip address 61.202.2.1 255.255.255.248

interface Ethernet 0/0.11
 description GYM
 encapsulation dot1q 11
 ip vrf forwarding GYM
 ip address 10.1.1.2 255.255.255.252

interface Ethernet 0/0.12
 description SCHOOL
 encapsulation dot1q 12
 ip vrf forwarding SCHOOL
 ip address 10.1.1.2 255.255.255.252

router ospf 11 vrf GYM
 network 10.1.1.0 0.0.0.255 area 1
 network 61.202.2.0 0.0.0.255 area 1

router ospf 22 vrf SCHOOL
 network 10.1.1.0 0.0.0.255 area 1
 network 61.202.2.0 0.0.0.255 area 1

show ip ospf neighbor

show ip route vrf GYM

show ip route vrf SCHOOL