A company wants to switch from static routing to a dynamic routing protocol to ease the administrative and operational overhead. The network topology is hub and spoke, and the branches use DMVPN back

ISIS (Intermediate System to Intermediate System) is more commonly used in large service provider or enterprise core networks and does not inherently offer the stub router concept or unequal-cost load balancing (without complex traffic engineering) as elegantly as EIGRP for this specific scenario.

EIGRP (Enhanced Interior Gateway Routing Protocol) is well-suited for hub-and-spoke topologies, offers efficient convergence, and supports unequal-cost load balancing, which aligns with the need to utilize both 100 Mbps links based on traffic utilization. Configuring branch routers as EIGRP stub routers limits the amount of routing information they receive, preserving their limited memory and CPU resources, while ECMP (Equal-Cost Multi-Path) could be used if path costs are equal, or unequal cost load balancing for more flexible utilization.

iBGP (Internal Border Gateway Protocol) is primarily designed for inter-AS routing and complex policy-based routing, not typically for internal routing within a single autonomous system in a hub-and-spoke enterprise scenario, especially with limited branch resources.

While OSPF (Open Shortest Path First) can work in hub-and-spoke, its default behavior for load balancing is equal-cost, and enabling unequal-cost load balancing typically requires advanced features or policy routing; also, a standard OSPF setup without careful summarization can consume more resources on branch routers than EIGRP stub.