300-420 · Question #318
A company wants to switch from static to dynamic routing. The branches use DMVPN back to the hub using two internet connections. One internet connection speed is 10 Mbps, and the other is 100 Mbps…
The correct answer is B. EIGRP with branch routers as stub routers and variance enabled. For a DMVPN hub-and-spoke topology with diverse link speeds and resource-constrained branch routers, EIGRP with stub router configuration and variance enabled is the optimal design choice for efficient and load-balanced traffic forwarding.
Question
A company wants to switch from static to dynamic routing. The branches use DMVPN back to the hub using two internet connections. One internet connection speed is 10 Mbps, and the other is 100 Mbps. All locations use Cisco routers; however, the branch routers have limited memory and CPU resources. Which routing protocol and design solution must the company choose for optimal traffic forwarding during peak traffic times?
Options
- AOSPF deployed in area 0 with branch routers connected back via virtual links
- BEIGRP with branch routers as stub routers and variance enabled
- CISIS with the hub and spoke routers configured in two different areas
- DiBGP with the hub routers set up as route reflectors
How the community answered
(17 responses)- A24% (4)
- B59% (10)
- C12% (2)
- D6% (1)
Why each option
For a DMVPN hub-and-spoke topology with diverse link speeds and resource-constrained branch routers, EIGRP with stub router configuration and variance enabled is the optimal design choice for efficient and load-balanced traffic forwarding.
OSPF with virtual links introduces design complexity and is generally not recommended for dynamic DMVPN spokes. OSPF's equal-cost multipathing would not effectively utilize the disparate 10 Mbps and 100 Mbps links for optimal traffic forwarding.
EIGRP is highly suitable for DMVPN, and configuring branch routers as stub routers limits their resource consumption. Enabling variance allows for unequal-cost load balancing, efficiently utilizing both the 10 Mbps and 100 Mbps internet connections to forward traffic optimally during peak times.
ISIS is generally more complex to configure than EIGRP and does not offer the same straightforward unequal-cost load balancing capabilities with variance, making it less ideal for leveraging mixed link speeds efficiently in this scenario.
iBGP is typically reserved for inter-AS routing or large-scale, policy-driven networks and is overly complex for a DMVPN overlay where simplicity and efficient resource utilization on branch routers are primary concerns.
Concept tested: DMVPN routing with EIGRP optimization
Source: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_eigrp/configuration/15-mt/ire-15-mt-book/ire-config-egrp.html
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