% Interface FastEthernet0/0.81 IP address 10.10.10.1 removed due to enabling VRF Company-A MBG001(config-if)#ip vrf forwarding Company-A In this example, the VRF for each company is assigned to its corresponding interface: MBG001(config)#interface f0/0.81
Simply enter the interface configuration mode then use command ip vrf forwarding. Note that VRF can be assigned to any kind of interface including VLAN and Loopback. Assigning VRF to an interfaceĪfter creating the VRF, the next step is assigning the VRF to an interface, or in this example is a sub-interface. On the output above, the interfaces column is blank because we haven’t assigned the VRF to any interface yet. To see list of VRF that has been created, use command show ip vrf in the privileged exec mode. In this example, command exit is used to escape the VRF configuration mode, and then another VRF named “ Company-B” is created for company B: MBG001(config-vrf)#exit In here, there are several advanced options that can be configured but for basic VRF implementation, this configuration can be skipped. Notice that after creating a VRF, the router will enter VRF configuration mode. In this example VRF for company A named “ Company-A” is created on MBG001: MBG001(config)#ip vrf Company-A To do so, use command ip vrf in the global configuration mode. The first thing to do is creating the VRF instance. VRF configuration is easy and consists of 2 simple steps, as explained below: 1. In this condition, the solution is to configure VRF on MBG001. % 10.10.10.0 overlaps with FastEthernet0/0.81įrom the output above, it is clear that the router rejects the IP address assignment for subinterface f0/0.82 because the IP address is overlap with what already assigned on f0/0.81. MBG001(config-if)#description Connection-to-Company-B MBG001(config-if)#description Connection-to-Company-A Unfortunately, there’s just one problem as message below appears on MBG001 when trying to configure the gateway interface for those VLANs: Therefore, separate VLAN is used where VLAN81 is for Company-A and VLAN82 is for Company-B. However, for some reason both companies needs to use the same network address but they refuse to expose their network to each other. The goal is to make company “A” network able to access Loopback1 address and “B” must be able to access Loopback2 address. Interface f0/0 on MBG001 connected to a switch and the switch connected to each of the company network. MustBeGeek uses a single router named MBG001 and it is shared for both company “A” and “B”. In this scenario, a service provider named MustBeGeek have two customers, namely “ Company A” and “ Company B”. The scenario below is the example where overlapping network address is used (pointed by the red arrow): However, there are certain causes where this condition is unavoidable (usually happens in a service provider network), and this is one of the reasons why understanding the way to configure VRF in Cisco IOS router is important. Usage of overlapping address should be avoided as much as possible. In this article, we are going to configure VRF in Cisco IOS router to establish connection for two LANs with overlapping network address. Cisco IOS router supports VRF by default. Due to its independency, it also allows the usage of overlapping IP address. This means a single router can have multiple separated routing table and each one is completely independent. Virtual Routing and Forwarding or VRF is a technology that supports multiple routing instance inside a single router (or layer-3 switch).