Configuring VRF Lite

This chapter describes how to configure VPN Routing and Forwarding Lite (VRF Lite) for the ML-Series cards. For additional information about the Cisco IOS commands used in this chapter, refer to the Cisco IOS Command Reference publication. This chapter contains the following major sections:

•Understanding VRF Lite

•Configuring VRF Lite

•VRF Lite Configuration Example

•Monitoring and Verifying VRF Lite

Note If you have already configured bridging, you may now proceed with configuring VRF Lite as an optional step.

Understanding VRF Lite

VRF is an extension of IP routing that provides multiple routing instances. It provides a separate IP routing and forwarding table to each VPN and is used in concert with MP-iBGP (Multi-Protocol internal BGP) between provider equipment (PE) routers to provide Layer 3 MPLS-VPN. However, ML-Series VRF implementation is without MP-iBGP. With VRF Lite, the ML Series is considered a PE-extension or a customer equipment (CE)-extension. VRF Lite is considered a PE-extension since its has VRF (but without MP-iBGP), and it is considered a CE-extension since this CE can have multiple VRFs and serves many customer with one CE box.

Under VRF Lite, an ML-Series CE can have multiple interfaces/subinterfaces with PE for different customers (while a normal CE is only for one customer). It holds VRFs (routing information) locally and it does not distribute the VRFs to its connected PE. It uses VRF information to direct traffic to the correct interfaces/subinterfaces when it receives traffic from customers' routers or from Internet service provider (ISP) PE router(s).

Configuring VRF Lite

Perform the following procedure to configure VRF Lite:

 
Command
Purpose

Step 1  

Router(config)# ip vrf vrf-name

Enters VRF configuration mode and assigns a VRF name.

Step 2  

Router(config-vrf)# rd 
route-distinguisher

Creates a VPN route distinguisher (RD). An RD creates routing and forwarding tables and specifies the default route distinguisher for a VPN. The RD is added to the beginning of the customer's IPv4 prefixes to change them into globally unique VPN-IPv4 prefixes.

Either RD is an ASN-relative RD, in which case it is composed of an autonomous system number and an arbitrary number, or it is an IP-address-relative RD, in which case it is composed of an IP address and an arbitrary number.

You can enter a route-distinguisher in either of these formats:

16-bit AS number: your 32-bit number
For example, 101:3.

32-bit IP address: your 16-bit number
For example, 192.168.122.15:1.

Step 3  

Router(config-vrf)# route-target {import 
| export | both} route-distinguisher

Creates a list of import and/or export route target communities for the specified VRF.

Step 4  

Router(config-vrf)# import map route-map

(Optional) Associates the specified route map with the VRF.

Step 5  

Router(config-vrf)# exit

Exits the current configuration mode and enters global configuration mode.

Step 6  

Router(config)# interface type number

Specifies an interface and enters interface configuration mode.

Step 7  

Router(config-vrf)# ip vrf forwarding 
vrf-name

Associates a VRF with an interface or subinterface.

Step 8  

Router(config-if)# end

Exits to privileged EXEC mode.

Step 9  

Router# copy running-config 
startup-config

(Optional) Saves configuration changes to NVRAM.

Example 13-1 shows an example of configuring a VRF. In the example, the VRF name is customer_a, the route-distinguisher is 1:1, and the interface type is Fast Ethernet, number 0.1.

Example 13-1 Configuring a VRF 

Router(config)# ip vrf customer_a

Router(config-vrf)# rd 1:1

Router(config-vrf)# route-target both 1:1

Router(config)# interface fastEthernet 0.1

Router(config-subif)# ip vrf forwarding customer_a

VRF Lite Configuration Example

Figure 13-1 shows an example of a VRF Lite configuration. The configurations for Router A and Router B are provided in Example 13-2 and Example 13-3, respectively. The associated routing tables are shown in Example 13-4 through Example 13-9.

Figure 13-1 VRF Lite—Sample Network Scenario

Example 13-2 Router A Configuration 

hostname Router_A

!

ip vrf customer_a

 rd 1:1

 route-target export 1:1

 route-target import 1:1

!

ip vrf customer_b

 rd 2:2

 route-target export 2:2

 route-target import 2:2

!

bridge 1 protocol ieee

bridge 2 protocol ieee

bridge 3 protocol ieee

!

!

interface FastEthernet0

 no ip address

!

interface FastEthernet0.1

 encapsulation dot1Q 2

 ip vrf forwarding customer_a

 ip address 192.168.1.1 255.255.255.0

 bridge-group 2

!

interface FastEthernet1

 no ip address

!

interface FastEthernet1.1

 encapsulation dot1Q 3

 ip vrf forwarding customer_b

 ip address 192.168.2.1 255.255.255.0

 bridge-group 3

!

interface POS0

 no ip address

 crc 32

 no cdp enable

 pos flag c2 1

!

interface POS0.1

 encapsulation dot1Q 1 native

 ip address 192.168.50.1 255.255.255.0

 bridge-group 1

!

interface POS0.2

 encapsulation dot1Q 2

 ip vrf forwarding customer_a

 ip address 192.168.100.1 255.255.255.0

 bridge-group 2

!

interface POS0.3

 encapsulation dot1Q 3

 ip vrf forwarding customer_b

 ip address 192.168.200.1 255.255.255.0

 bridge-group 3

!

router ospf 1

 log-adjacency-changes

 network 192.168.50.0 0.0.0.255 area 0

!

router ospf 2 vrf customer_a

 log-adjacency-changes

 network 192.168.1.0 0.0.0.255 area 0

 network 192.168.100.0 0.0.0.255 area 0

!

router ospf 3 vrf customer_b

 log-adjacency-changes

 network 192.168.2.0 0.0.0.255 area 0

 network 192.168.200.0 0.0.0.255 area 0

!

Example 13-3 Router_B Configuration 

hostname Router_B

!

ip vrf customer_a 

rd 1:1

 route-target export 1:1

 route-target import 1:1

!

ip vrf customer_b

 rd 2:2

 route-target export 2:2

 route-target import 2:2

!

bridge 1 protocol ieee

bridge 2 protocol ieee

bridge 3 protocol ieee

!

!

interface FastEthernet0

 no ip address

!

interface FastEthernet0.1

 encapsulation dot1Q 2

 ip vrf forwarding customer_a

 ip address 192.168.4.1 255.255.255.0

 bridge-group 2

!

interface FastEthernet1

 no ip address

!

interface FastEthernet1.1

 encapsulation dot1Q 3

 ip vrf forwarding customer_b

 ip address 192.168.5.1 255.255.255.0

 bridge-group 3

!

interface POS0

 no ip address

 crc 32

 no cdp enable

 pos flag c2 1

!

interface POS0.1

 encapsulation dot1Q 1 native

 ip address 192.168.50.2 255.255.255.0

 bridge-group 1

!

interface POS0.2

 encapsulation dot1Q 2

 ip vrf forwarding customer_a

 ip address 192.168.100.2 255.255.255.0

 bridge-group 2

!

interface POS0.3

 encapsulation dot1Q 3

 ip vrf forwarding customer_b

 ip address 192.168.200.2 255.255.255.0

 bridge-group 3

!

router ospf 1

 log-adjacency-changes

 network 192.168.50.0 0.0.0.255 area 0

!

router ospf 2 vrf customer_a

 log-adjacency-changes

 network 192.168.4.0 0.0.0.255 area 0

 network 192.168.100.0 0.0.0.255 area 0

!

router ospf 3 vrf customer_b

 log-adjacency-changes

 network 192.168.5.0 0.0.0.255 area 0

 network 192.168.200.0 0.0.0.255 area 0

!

Example 13-4 Router_A Global Routing Table 

Router_A# sh ip route

Codes: C - connected, S - static, I - IGRP, 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, E - EGP

       i - IS-IS, 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


C    192.168.50.0/24 is directly connected, POS0.1

Example 13-5 Router_A customer_a VRF Routing Table 

Router_A# show ip route vrf customer_a

Codes: C - connected, S - static, I - IGRP, 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, E - EGP

       i - IS-IS, 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


O    192.168.4.0/24 [110/2] via 192.168.100.2, 00:15:35, POS0.2

C    192.168.1.0/24 is directly connected, FastEthernet0.1

C    192.168.100.0/24 is directly connected, POS0.2

Example 13-6 Router_A customer_b VRF Routing Table 

Router_A# show ip route vrf customer_b

Codes: C - connected, S - static, I - IGRP, 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, E - EGP

       i - IS-IS, 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


C    192.168.200.0/24 is directly connected, POS0.3

O    192.168.5.0/24 [110/2] via 192.168.200.2, 00:10:32, POS0.3

C    192.168.2.0/24 is directly connected, FastEthernet1.1

Example 13-7 Router_B Global Routing Table 

Router_B# sh ip route

Codes: C - connected, S - static, I - IGRP, 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, E - EGP

       i - IS-IS, 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


C    192.168.50.0/24 is directly connected, POS0.1

Example 13-8 Router_B customer_a VRF Routing Table 

Router_B# sh ip route vrf customer_a

Codes: C - connected, S - static, I - IGRP, 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, E - EGP

       i - IS-IS, 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


C    192.168.4.0/24 is directly connected, FastEthernet0.1

O    192.168.1.0/24 [110/2] via 192.168.100.1, 00:56:24, POS0.2

C    192.168.100.0/24 is directly connected, POS0.2

Example 13-9 Router_B customer_b VRF Routing Table 

Router_B# show ip route vrf customer_b

Codes: C - connected, S - static, I - IGRP, 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, E - EGP

       i - IS-IS, 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


C    192.168.200.0/24 is directly connected, POS0.3

C    192.168.5.0/24 is directly connected, FastEthernet1.1

O    192.168.2.0/24 [110/2] via 192.168.200.1, 00:10:51, POS0.3

Monitoring and Verifying VRF Lite

Table 13-1 shows the privileged EXEC commands for monitoring and verifying VRF Lite.

Table 13-1 Commands for Monitoring and Verifying VRF Lite

Command
Purpose 
Router# show ip vrf

Displays the set of VRFs and interfaces. 

Router# show ip route vrf vrf-name

Displays the IP routing table for a VRF. 

Router# show ip protocols vrf vrf-name

Displays the routing protocol information for a VRF. 

Router# ping vrf vrf-name ip ip-address

Pings an IP address that has a specific VRF.