With Layer 3 MPLS VPN implementations on Cisco IOS XR PE routers, an interface is assigned to a VRF using the vrf command in which configuration mode?

Question

Options

• ARP/0/RP0/CPU0:PE(config-bgp)#
• BRP/0/RP0/CPU0:PE(config-if)#
• CRP/0/RP0/CPU0:PE(config-bgp-af)#
• DRP/0/RP0/CPU0:PE(config-vrf)#

• A
  4% (1)
• B
  89% (25)
• C
  7% (2)

Explanation

On Cisco IOS XR, assigning an interface to a VRF is done under interface configuration mode (config-if) using the vrf command - for example, interface GigabitEthernet0/0/0/0 followed by vrf <vrf-name>. This is the correct placement because VRF membership is a property of the interface itself, binding that physical or logical port to a specific routing and forwarding table.

Why the distractors are wrong:

• A (config-bgp) - BGP configuration mode is where you define neighbors, address families, and VPNv4/VPNv6 route targets, not where you attach interfaces to VRFs.
• C (config-bgp-af) - BGP address-family mode handles route distinguishers and route targets for a VRF within BGP, not interface-to-VRF assignment.
• D (config-vrf) - VRF configuration mode (vrf <name>) is where you define the VRF itself (RD, import/export RTs), not where you bind an interface to it.

Memory tip: Think of it as "the interface joins the VRF" - you go to the interface first, then tell it which VRF it belongs to. Interface config = interface properties, and VRF membership is one of those properties.

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