EVPN advertises all the host information learned in the Virtual Terminal End Point (VTEP) as EVPN Type‐2 routes to the other peer VTEPs in the fabric. In addition to these Type-2 routes, the tenant that hosts these VTPEs could have route entries from connected networks, static routes, or routes learned from OSPF/BGP protocols.
These non-EVPN IP prefixes present in a VTEP are advertised as EVPN Type‐5 routes to the other peer VTEPs within a tenant Virtual Routing and Forwarding (VRF). Advertisements of both IPv4 and IPv6 prefixes are supported. The figure below illustrates an EVPN fabric that connects with a non-EVPN network and learns the route to the external subnet using a Type-5 route advertisement.
Figure 1. Type-5 deployment
The figure shows a two-step process of learning the external route by the EVPN fabric as a Type-5 route.
In Step1, Leaf2 learns a non-EVPN route from an external router. The external router has point-to-point eBGP link with Leaf2. Within Leaf2, tenant1 VRF learns the subnet through its eBGP neighbor and knows that subnet 100.65.21.0/24 is reachable through the external router.
In Step2, after the learning, a Type-5 route protocol data unit (PDU) is created with subnet address as IP prefix and advertises into the EVPN fabric. This Type-5 route PDU is picked up by Leaf1 and inserts into its route table as EVPN route. This entry shows that, to reach subnet 100.65.21.0/24 from Leaf1, the packet must be routed to Leaf2/VTEP2, which then determines how to reach this subnet on the external router.
Now both Leaf1 and Leaf2 have a route entry in their route table for the subnet 100.65.1.0/24. The deployment use case shows the steps used to configure both steps.