300-410 · Question #26
Which protocol is used in a DMVPN network to map logical IP address to physical IP addresses?
The correct answer is D. NHRP. DMVPN networks use NHRP to dynamically map logical tunnel IP addresses to physical NBMA IP addresses, facilitating direct spoke-to-spoke communication without traffic Hair-pinning through the hub.
Question
Options
- ABGP
- BLLDP
- CEIGRP
- DNHRP
How the community answered
(62 responses)- A2% (1)
- B5% (3)
- C3% (2)
- D90% (56)
Why each option
DMVPN networks use NHRP to dynamically map logical tunnel IP addresses to physical NBMA IP addresses, facilitating direct spoke-to-spoke communication without traffic Hair-pinning through the hub.
BGP is a routing protocol for exchanging network reachability information between autonomous systems, not for mapping logical to physical IP addresses within a DMVPN overlay.
LLDP is a Layer 2 protocol used for discovering neighboring devices on a local segment and has no role in DMVPN IP address resolution.
EIGRP is an interior gateway routing protocol (IGRP) used for exchanging routing information within an autonomous system, not for the address resolution function of DMVPN.
NHRP (Next Hop Resolution Protocol) is an essential component of DMVPN, providing the mechanism for routers to discover the physical IP addresses associated with other routers' logical tunnel IP addresses. This dynamic mapping enables spokes to establish direct IPsec tunnels to each other, reducing latency and offloading the hub.
Concept tested: DMVPN NHRP address resolution
Source: https://www.cisco.com/c/en/us/td/docs/ios/sec_prot_suite/configuration/guide/ipsec_ig/ipsec_nhrp.html
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