300-415 Question #286: Real Exam Question with Answer & Explanation

Question

Options

• Apolicy lists vpn-list VPN2 vpn2 ! site-list hub_sites site-id 1-2 ! control-policy vpn_multi-topology sequence 10 match route site-list hub_sites vpn-list VPN2 ! action accept ! sequence 20 match route vpn-list VPN2 ! action reject ! default-action accept
• Bpolicy lists vpn-list VPN2 vpn2 ! site-list hub_sites site-id 1-2 ! control-policy vpn_multi-topology sequence 10 match route site-list hub_sites vpn-list VPN2 ! action accept ! sequence 20 match route vpn-list VPN2 ! action reject ! default-action accept
• Cpolicy lists vpn-list VPN2 vpn2 ! site-list branch_sites site-id 1-100 ! control-policy vpn_multi-topology sequence 10 match route site-list branch_sites vpn-list VPN2 ! action accept set tloc 100.1.1.1 color mpls ! ! default-action accept
• Dpolicy lists vpn-list VPN2 vpn2 ! site-list branch_sites site-id 100-200 ! control-policy vpn_multi-topology sequence 10 match route site-list branch_sites vpn-list VPN2 ! action accept set tloc 1.1.1.1 color red ! ! default-action accept

Explanation

The provided control policy establishes a strict hub-and-spoke topology for VPN2 by accepting routes from designated hub sites while rejecting all other routes within VPN2 when applied in the 'out' direction on branch devices.

Common mistakes.

• A. This option is identical to option B and correctly implements the hub-and-spoke topology. Assuming distinct options are intended, B is the designated correct choice.
• C. This policy accepts routes from branch_sites and attempts to set a TLOC, which would allow branches to learn routes directly from other branches, thus breaking a strict hub-and-spoke topology.
• D. This policy also accepts routes from branch_sites and sets a TLOC, which would allow branches to learn routes from other branches and prevent the establishment of a strict hub-and-spoke topology.

Concept tested. Cisco SD-WAN control policy for hub-and-spoke

Reference. https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/policy-book/sdwan-policy-book_chapter_011.html

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