400-007 · Question #309
A large enterprise customer has a single router that uses two active/active 10-Mbps internet links in one of its offices. Each link currently handles approximately 7 Mbps of traffic, which is close…
The correct answer is D. Use dynamic routing for equal-cost multipath. The core problem is that static routing does not automatically adapt to link failures. With static routing in an active/active configuration, when one 10-Mbps link fails, traffic may not fail over gracefully or quickly, causing widespread performance degradation. Implementing…
Question
A large enterprise customer has a single router that uses two active/active 10-Mbps internet links in one of its offices. Each link currently handles approximately 7 Mbps of traffic, which is close to the full link capacity. When a link fails, the failure leads to significantly degraded performance of all applications. Static routing is used. The current ISP cannot deliver additional bandwidth capacity on the existing links. The customer needs a network design that is resistant to failure, but does not increase CAPEX. Which solution should be proposed to the customer?
Options
- AImplement quality of service on the current links.
- BAdd a third link to the current router.
- CAdd an additional edge router connected to a second ISP.
- DUse dynamic routing for equal-cost multipath.
How the community answered
(22 responses)- A23% (5)
- B14% (3)
- C5% (1)
- D59% (13)
Explanation
The core problem is that static routing does not automatically adapt to link failures. With static routing in an active/active configuration, when one 10-Mbps link fails, traffic may not fail over gracefully or quickly, causing widespread performance degradation. Implementing dynamic routing (such as OSPF or EIGRP) with Equal-Cost Multipath (ECMP) allows the router to automatically detect link failures via routing protocol hello mechanisms and reconverge, shifting all traffic to the surviving link. When both links are healthy, ECMP load-balances traffic across both. This requires only a configuration change-no new hardware-satisfying the no-CAPEX-increase constraint. Option A (QoS) can prioritize traffic but does not improve fault tolerance; if a link fails, lower-priority traffic still suffers. Options B and C require purchasing additional hardware or circuits, directly increasing CAPEX.
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