300-320 · Question #143
A network team must provide a redundant secure connection between two entities using OSPF. The primary connection will be an Ethernet Private Line and the secondary connection will be a site-to-site…
The correct answer is A. GRE Tunnel. OSPF requires a broadcast or point-to-point link to form neighbor adjacencies, which a raw IPSec VPN does not provide. A GRE tunnel creates a virtual point-to-point interface over the VPN, allowing OSPF to run across it.
Question
A network team must provide a redundant secure connection between two entities using OSPF. The primary connection will be an Ethernet Private Line and the secondary connection will be a site-to-site VPN. What needs to be configured in order to support routing requirements for over the VPN connection?
Options
- AGRE Tunnel
- BHTTPS
- CRoot Certificate
- DAAA Server
How the community answered
(64 responses)- A73% (47)
- B5% (3)
- C14% (9)
- D8% (5)
Why each option
OSPF requires a broadcast or point-to-point link to form neighbor adjacencies, which a raw IPSec VPN does not provide. A GRE tunnel creates a virtual point-to-point interface over the VPN, allowing OSPF to run across it.
GRE (Generic Routing Encapsulation) creates a logical point-to-point tunnel interface over the IPSec VPN connection. OSPF can then form adjacencies and exchange routing information across this tunnel, enabling dynamic routing over the secondary VPN path while the primary Ethernet Private Line carries traffic normally.
HTTPS is an application-layer web protocol and has no role in enabling routing protocols over a VPN.
A root certificate is used for PKI trust and authentication, not for enabling OSPF routing across a VPN tunnel.
An AAA server handles authentication, authorization, and accounting for network access, not routing protocol support over a VPN.
Concept tested: GRE tunnel enabling OSPF over IPSec VPN
Source: https://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/13703-17.html
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