300-415 Question #219: Real Exam Question with Answer & Explanation

The correct answer is A: OSPF. On the service side of a Cisco SD-WAN WAN Edge router, OSPF is commonly used to advertise routes to and from the local area network (LAN) segment. This allows the WAN Edge to learn local prefixes and propagate them into the SD-WAN fabric.

WAN Edge Router Deployment

Question

Which protocol advertises WAN Edge routes on the service side?

Options

AOSPF
BBGP
CISIS
DEIGRP

Explanation

On the service side of a Cisco SD-WAN WAN Edge router, OSPF is commonly used to advertise routes to and from the local area network (LAN) segment. This allows the WAN Edge to learn local prefixes and propagate them into the SD-WAN fabric.

Common mistakes.

B. BGP (Border Gateway Protocol) is primarily an exterior gateway protocol used for routing between autonomous systems, rather than the most common choice for service-side advertisement within an enterprise LAN.
C. ISIS (Intermediate System to Intermediate System) is an IGP primarily used by service providers and is less common for enterprise service-side routing compared to OSPF or EIGRP.
D. EIGRP (Enhanced Interior Gateway Routing Protocol) is a Cisco proprietary routing protocol, which while effective, is not as universally adopted or as frequently the primary 'service side' protocol choice in general SD-WAN contexts as OSPF.

Concept tested. WAN Edge Service-Side Routing Protocols

Reference. https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/sdwan-xe-gs-book/sdwan-routing.html

Topics

#WAN Edge routing#Service side routing#OSPF

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