300-730 · Question #93
Refer to the exhibit. Which two conclusions should be drawn from the DMVPN phase 2 configuration? (Choose two.)
The correct answer is C. EIGRP is used as the dynamic routing protocol. E. Spoke-to-spoke communication is allowed.. The exhibit shows a DMVPN Phase 2 configuration using EIGRP as the dynamic routing protocol, and Phase 2 inherently supports spoke-to-spoke communication through dynamic NHRP resolution.
Question
Options
- ANext-hop-self is required.
- BEIGRP neighbor adjacency will fail.
- CEIGRP is used as the dynamic routing protocol.
- DEIGRP route redistribution is not allowed.
- ESpoke-to-spoke communication is allowed.
How the community answered
(32 responses)- A9% (3)
- B16% (5)
- C72% (23)
- D3% (1)
Why each option
The exhibit shows a DMVPN Phase 2 configuration using EIGRP as the dynamic routing protocol, and Phase 2 inherently supports spoke-to-spoke communication through dynamic NHRP resolution.
In DMVPN Phase 2, `next-hop-self` must NOT be configured on the hub because it rewrites the route's next-hop to the hub's address, which prevents spokes from performing NHRP resolution to the correct destination spoke NBMA address.
EIGRP neighbor adjacency will form successfully in Phase 2 because the multipoint GRE interface allows EIGRP hello packets to reach all NHRP-registered spoke peers.
The exhibit contains `router eigrp` and associated network statements applied to the tunnel interface, confirming EIGRP is the dynamic routing protocol distributing prefixes across the DMVPN overlay. EIGRP operates natively over the multipoint GRE interface and exchanges routes with all NHRP-registered peers.
EIGRP route redistribution is not restricted in DMVPN Phase 2 - routes can be redistributed between EIGRP and other routing protocols as required by the design.
DMVPN Phase 2 allows spokes to dynamically discover each other's NBMA addresses through NHRP resolution, enabling direct spoke-to-spoke GRE tunnels to be built without routing traffic through the hub. This phase-specific behavior confirms that spoke-to-spoke communication is permitted once the NHRP mapping is resolved.
Concept tested: DMVPN Phase 2 EIGRP routing and spoke-to-spoke communication
Source: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_eigrp/configuration/xe-16/ire-xe-16-book/ire-dmvpn.html
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