• VRF (Virtual Routing and Forwarding) allows a router to maintain multiple independent routing tables on the same physical device.
    Each VRF acts as a separate virtual router with its own interfaces and routes.

    The concept is the same as VLANs, but at a different layer.

    • VLANs isolate traffic at Layer 2 by creating separate MAC address tables.

    • VRFs isolate traffic at Layer 3 by creating separate routing tables.

    VLAN vs VRF diagram showing Layer 2 isolation with VLANs and Layer 3 isolation with VRFs using CLIENT1 and CLIENT2

    Figure 1 – VLANs vs VRFs

    But in real service provider networks, your VRFs must travel across multiple routers end-to-end.
    This is where VRF-Lite at the CCNP level begins.

    The Scenario

    You are the network engineer of a service provider.
    Two customers need connectivity through your ISP router.

    • CLIENT1 has two sites: HQ1 and BR1.

    • CLIENT2 has two sites: HQ2 and BR2.

    All four customer routers connect to your central ISP router through dedicated physical interfaces.

    ISP topology with HQ1 and BR1 on the left and HQ2 and BR2 on the right all connected to the central ISP router

    Figure 2 – ISP multi-customer topology

    Your objective is clear: CLIENT1 and CLIENT2 must be completely isolated from each other, even though they share the same physical ISP router.

    The VRF Solution

    With VRF, you segment the network into isolated customer domains.
    Each customer's links belong to its own VRF.

    • CLIENT1 links (HQ1 and BR1) are shown in orange on the left.

    • CLIENT2 links (HQ2 and BR2) are shown in green on the right.

    The dashed line represents the complete isolation between the two VRFs.

    ISP topology with CLIENT1 links in orange and CLIENT2 links in green separated by a dashed line

    Figure 3 – VRF network segmentation

    From the perspective of VRF CLIENT1, VRF CLIENT2 does not exist.
    They share the same physical ISP router, but they live in completely separate worlds.

    Answer the question below

    What does each VRF maintain to keep customer traffic separated?

    The Modern Syntax: vrf definition

    Older Cisco IOS used the ip vrf command to create VRFs.
    That is the legacy syntax, limited to IPv4 only.

    Modern Cisco IOS and IOS-XE use vrf definition.
    This command supports both IPv4 and IPv6 through address families.
    This is the syntax you need for the CCNP ENCOR blueprint.

    Create the customer VRFs on every router in the topology.

    On the ISP, create both VRFs:

    ISP# conf t
Enter configuration commands, one per line.  End with CNTL/Z.
ISP(config)# vrf definition CLIENT1
ISP(config-vrf)# address-family ipv4
ISP(config-vrf-af)# exit-address-family
ISP(config-vrf)# exit

ISP(config)# vrf definition CLIENT2
ISP(config-vrf)# address-family ipv4
ISP(config-vrf-af)# exit-address-family
ISP(config-vrf)# exit

    On HQ1, create VRF CLIENT1:

    HQ1# conf t
Enter configuration commands, one per line.  End with CNTL/Z.
HQ1(config)# vrf definition CLIENT1
HQ1(config-vrf)# address-family ipv4
HQ1(config-vrf-af)# exit-address-family
HQ1(config-vrf)# exit

    On BR1:

    BR1# conf t
Enter configuration commands, one per line.  End with CNTL/Z.
BR1(config)# vrf definition CLIENT1
BR1(config-vrf)# address-family ipv4
BR1(config-vrf-af)# exit-address-family
BR1(config-vrf)# exit

    On HQ2, create VRF CLIENT2:

    HQ2# conf t
Enter configuration commands, one per line.  End with CNTL/Z.
HQ2(config)# vrf definition CLIENT2
HQ2(config-vrf)# address-family ipv4
HQ2(config-vrf-af)# exit-address-family
HQ2(config-vrf)# exit

    On BR2:

    BR2# conf t
Enter configuration commands, one per line.  End with CNTL/Z.
BR2(config)# vrf definition CLIENT2
BR2(config-vrf)# address-family ipv4
BR2(config-vrf-af)# exit-address-family
BR2(config-vrf)# exit

    The address-family ipv4 block activates IPv4 routing inside this VRF.
    Without it, the VRF exists but cannot process any IPv4 traffic.

    Answer the question below

    Which command replaces ip vrf in modern IOS-XE for creating VRFs?