You issue the following command on a Cisco Nexus 7000 switch:
vrf context default
Which of the following is most likely to occur?
- A new VDC named default will be created.
- A new VRF instance named default will be created.
- The switch will return an error because the default VRF already exists.
- The switch will be placed into VRF configuration mode for an existing VRF.
Most likely, the switch will be placed into virtual routing and forwarding (VRF) configuration mode for the existing default VRF. There are two VRF instances configured on a Nexus 7000 by default: the management VRF and the default VRF. The default VRF includes all Layer 3 interfaces until you assign those interfaces to another VRF. Similarly, the default VRF runs any routing protocols that are configured unless those routing protocols are assigned to another VRF. All show and exec commands that are issued in the default VRF apply to the default routing context. Unless an administrator configures other VRFs on a Nexus 7000, any forwarding configurations that are made by the administrator will operate in the default VRF. The management VRF, on the other hand, is used only for management, includes only the mgmt 0 interface, and uses only static routing.
The vrf context name command can be used to create a new VRF or to enter VRF configuration mode for an existing VRF. Because the Nexus 7000 is already configured with a management VRF, issuing the command in this scenario places the device into VRF configuration mode for that VRF. Similarly, issuing the vrf context management command would place the switch into VRF configuration mode for the existing management VRF.
VRFs are used to logically separate Open Systems Interconnection (OSI) networking model Layer 3 networks. Therefore, it is possible to have overlapping Internet Protocol version 4 (IPv4) or Internet Protocol version 6 (IPv6) addresses in environments that contain multiple tenants. However, an interface that has been assigned to a given VRF cannot be simultaneously assigned to another VRF. The address space, routing process, and forwarding table that are used within a VRF are local to that VRF.