Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) — Question 242

How does Inter-AS Option-A function when two PE routers in different autonomous systems are directly connected?

Answer options

• A. The two routers share all Inter-AS VPNv4 routes and redistribute routes within an IBGP session to provide end-to-end reach.
• B. The two routers establish an MP-EBGP session to share their customers' respective VPNv4 routes.
• C. The two routers treat one another as CE routers and advertise unlabeled IPv4 routes through an EBGP session.
• D. The two routers share VPNv4 routes over a multihop EBGP session and set up an Inter-AS tunnel using one another's label.

Correct answer: C

Explanation

The correct answer is C because in Inter-AS Option-A, the PE routers function as if they are CE routers, exchanging unlabeled IPv4 routes over an EBGP session. Options A and B incorrectly describe the nature of the route sharing and redistribution methods, while option D misrepresents the connection type and usage of labels.