300-730 · Question #9
Which benefit of FlexVPN is a limitation of DMVPN using IKEv1?
The correct answer is B. IKE implementation can install routes in routing table.. FlexVPN uses IKEv2, which can inject routes directly into the routing table - a capability IKEv1 used in DMVPN lacks entirely.
Question
Options
- AGRE encapsulation allows for forwarding of non-IP traffic.
- BIKE implementation can install routes in routing table.
- CNHRP authentication provides enhanced security.
- DDynamic routing protocols can be configured.
How the community answered
(37 responses)- A8% (3)
- B78% (29)
- C11% (4)
- D3% (1)
Why each option
FlexVPN uses IKEv2, which can inject routes directly into the routing table - a capability IKEv1 used in DMVPN lacks entirely.
GRE encapsulation for non-IP traffic forwarding is available in both DMVPN and FlexVPN deployments, so it is not a FlexVPN-specific benefit over DMVPN.
IKEv2, the foundation of FlexVPN, supports route injection through the IKEv2 authorization framework, allowing the IKE process to programmatically install routes into the routing table during tunnel establishment. IKEv1, used in traditional DMVPN, has no equivalent mechanism and requires dynamic routing protocols running over GRE to achieve similar reachability. This native route installation is a defining advantage of FlexVPN over IKEv1-based DMVPN.
NHRP authentication is a core feature of DMVPN itself, not a capability introduced by FlexVPN or restricted from IKEv1-based designs.
Dynamic routing protocols such as EIGRP and OSPF can be configured over both DMVPN with IKEv1 and FlexVPN with IKEv2, so this is not a differentiating limitation of IKEv1.
Concept tested: IKEv2 route injection advantage over IKEv1
Source: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/sec_conn_ikevpn/configuration/xe-16/sec-conn-ikevpn-xe-16-book/sec-conn-flxvpn-overview.html
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