Virtual Router and Forwarding instances (VRFs) are similar to VRs. VRFs are created as children of user VRs or VR-Default, and each VRF supports Layer 3 routing and forwarding. The routing tables for each VRF are separate from the tables for other VRs and VRFs, so VRFs can support overlapping address space. The primary differences between VRs and VRFs are:
There are two types of VRFs:
Use VRFs instead of VRs when your network plan calls for more than 63 virtual routers or when you want to create Layer 3 VPNs. Use VRs instead of VRFs when the routing protocol you want to use is not supported on a VRF.
When a new VRF is created, by default, no ports are assigned, no VLAN interface is created, and no support for any routing protocols is added. When you add a protocol to a VRF, an instance of the protocol is created in the protocol process running in the parent VR, if the protocol process exists. If no protocol process is running in the parent VR, a process is started and a protocol instance corresponding to this VRF is created within that process.
The rest of this chapter uses the following terms to identify the different types of VRs and VRFs to which features and commands apply:
NoteVRFs are supported only on the platforms listed for the VRF feature in the Switch Engine 32.3 Feature License Requirements document. When a SummitStack contains switches that do not support VRFs, the ports on those devices cannot be added to a VRF.