VRF Lite
This technology is popular in networks with overlapping IP ranges.
The popular example is ISPs, which carry customer traffic.
VRF Lite doesn’t communicate how it’s VRFs work to the other router, so both of these boxes are configured by hand.
Topology
R1 R2
┌────────────┐ ┌────────────┐
│ ┌───────┐ │ │ ┌───────┐ │
│ │vrf ┌─┴──┤.1 .2├──┴─┐vrf │ │
│ │ red │G0/0├─────────────────┤G0/0│ red │ │
│ │ └─┬──┤ 10.0.0.0/24 ├──┬─┘ │ │
│ ├───────┤ │ │ ├───────┤ │
│ │vrf ┌─┴──┤.1 .2├──┴─┐vrf │ │
│ │ blue│G0/1├─────────────────┤G0/1│ blue│ │
│ │ └─┬──┤ 10.0.0.0/24 ├──┬─┘ │ │
│ └───────┘ │ │ └───────┘ │
└────────────┘ └────────────┘
Config
!
! R1 gets .1 for both interfaces
!
! R2 gets .2 for both interfaces
!
vrf definition red
address-family ipv4
exit-address-family
!
vrf definition blue
address-family ipv4
exit-address-family
!
interface GigabitEthernet0/0
vrf forwarding red
ip address 10.0.0.1 255.255.255.0
!
interface GigabitEthernet0/1
vrf forwarding blue
ip address 10.0.0.1 255.255.255.0
Validation
Routes
R1# show ip route
Routing Table: red
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
[output omitted]
Gateway of last resort is not set
No routes in the global table.
R1# show ip route vrf red
Routing Table: red
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
[output omitted]
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 10.0.0.0/24 is directly connected, GigabitEthernet0/0
L 10.0.0.1/32 is directly connected, GigabitEthernet0/0
1 connected route in vrf red
R1# show ip route vrf blue
Routing Table: blue
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
[output omitted]
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 10.0.0.0/24 is directly connected, GigabitEthernet0/1
L 10.0.0.1/32 is directly connected, GigabitEthernet0/1
1 connected route in vrf blue
Ping
R1# ping 10.0.0.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.0.0.2, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
Ping in the global table fails.
R1# ping vrf red 10.0.0.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.0.0.2, timeout is 2 seconds:
.!!!!
Success rate is 80 percent (4/5), round-trip min/avg/max = 3/3/4 ms
Ping in vrf red works.
R1# ping vrf blue 10.0.0.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.0.0.2, timeout is 2 seconds:
.!!!!
Success rate is 80 percent (4/5), round-trip min/avg/max = 3/3/4 ms
Ping in vrf blue works.