VRFs enable L3 control and data plane isolation within a switch. But sometimes traffic must flow between VRFs. In the multitenancy use case, hosts in the VLAN 20 subnet need a path to hosts in the VLAN 30 subnet, and conversely. This flow can be accomplished with the route leaking feature.

Route leaking enables routes in either a default or nondefault VRF to be presented to another VRF and be placed in its routing table. Static and dynamic routes can be leaked. Route leaking must be configured symmetrically in both the source and destination VRFs. With dynamic route leaking, you can obtain more granular control with route maps.

Dynamic route leaking is shown in the following example because OSPF is used. Routes are leaked between the sales and marketing tenants for the VLAN 20 interfaces in both Rack-1 and Rack-2 S5248S switches. See the following table.

Dynamic route leaking is configured using the route-export and route-import commands under each VRF in each switch. These commands export and import all routes between VRFs local to the switch.