Which three routing protocols can the Cisco WAN Edge router use for learning reachability information from the service-side interfaces? (Choose three.)
- RIPv1
- EIGRP
- OSPF
- IS-IS
- BGP
Explanation: The Cisco WAN Edge router functions as the data plane element of the SD-WAN fabric, responsible for establishing secure connectivity and forwarding data between sites. To learn reachability information from the service-side (LAN) interfaces, these routers support several traditional routing protocols:
- OSPF: WAN Edge routers support both OSPFv2 and OSPFv3 for learning routes from the local service-side network.
- EIGRP: This protocol is explicitly used for learning reachability information from service-side interfaces and for brownfield integration with non-SD-WAN sites.
- BGP: This is a standard routing protocol used on the service-side to exchange prefixes with local site routers.
Once these routes are learned from the service-side (configured in VPNs 1 through 65535), they are redistributed into the Overlay Management Protocol (OMP) to be advertised as service-side routes (vRoutes) across the SD-WAN overlay.
Note: While the sources state that RIPv2 is also supported, RIPv1 and IS-IS are not listed as options for learning reachability from the service-side interfaces. (IS-IS is instead recommended for use in the network underlay for physical connectivity).
Related exam: Modules 23 – 26: Checkpoint Exam: Software-Defined Networking Answers (CCNP ENCOR v9)
