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 network traffic for customer Gym and School. Each customer has isolated routing even though they use the same IP addresses.

ISP-1

! Create virtual router instances for Gym and School
ip vrf GYM
ip vrf SCHOOL

! Assign the interface to virtual router instance GYM
interface Ethernet 0/1
 description GYM
 ip vrf forwarding GYM
 ip address 61.201.1.1 255.255.255.248
 ip ospf 11 area 1

! Assign a sub-interface to virtual router GYM
interface Ethernet 0/0.11
 description GYM
 encapsulation dot1q 11
 ip vrf forwarding GYM
 ip address 10.1.1.1 255.255.255.252
 ip ospf 11 area 1

! Assign a sub-interface to virtual router SCHOOL
interface Ethernet 0/0.12
 description SCHOOL
 encapsulation dot1q 12
 ip vrf forwarding SCHOOL
 ip address 10.1.1.1 255.255.255.252
 ip ospf 12 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
 ip ospf 11 area 1

interface Ethernet 0/2
 description SCHOOL
 ip vrf forwarding SCHOOL
 ip address 61.202.2.1 255.255.255.248
 ip ospf 12 area 1

interface Ethernet 0/0.11
 description GYM
 encapsulation dot1q 11
 ip vrf forwarding GYM
 ip address 10.1.1.2 255.255.255.252
 ip ospf 11 area 1

interface Ethernet 0/0.12
 description SCHOOL
 encapsulation dot1q 12
 ip vrf forwarding SCHOOL
 ip address 10.1.1.2 255.255.255.252
 ip ospf 12 area 1

show ip ospf neighbor - ISP-1 has two neighbors pointing to the same router ISP-2

show ip route vrf GYM

show ip route vrf SCHOOL