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OSPF vs EIGRP: what is the difference?
In short: OSPF works on any vendor’s equipment, uses cost based on bandwidth and organises large networks into areas. EIGRP, originally Cisco-only and now an informational RFC, converges very quickly using DUAL and feasible successors and supports unequal-cost load balancing.
OSPF vs EIGRP in one sentence
OSPF is the vendor-neutral link-state routing protocol used almost everywhere, while EIGRP is Cisco’s fast-converging advanced distance-vector protocol.
Side-by-side comparison
| Feature | OSPF | EIGRP |
|---|---|---|
| Type | Link-state | Advanced distance-vector |
| Standard | Open standard (RFC 2328) | Cisco, published as RFC 7868 (informational) |
| Algorithm | SPF (Dijkstra) | DUAL |
| Metric | Cost (based on bandwidth) | Composite: bandwidth and delay by default |
| Administrative distance | 110 | 90 internal, 170 external |
| Hierarchy | Areas, backbone area 0 | Flat; summarise anywhere |
| Load balancing | Equal cost | Equal and unequal cost (variance) |
| Multicast address | 224.0.0.5 / 224.0.0.6 | 224.0.0.10 |
What is OSPF?
Open Shortest Path First floods link-state information so every router in an area has the same map, then calculates best paths with Dijkstra’s algorithm. It is supported by every major vendor and is the default choice for multi-vendor networks.
What is EIGRP?
Enhanced Interior Gateway Routing Protocol keeps backup routes (feasible successors) ready, so it can switch paths almost instantly. It is simple to configure but is mainly found in Cisco-only networks.
Which one should you use?
Choose OSPF for multi-vendor networks and when you want a widely understood standard. EIGRP can be a good fit in an all-Cisco network that values fast convergence and simple configuration. For the CCNA exam, focus on OSPF; EIGRP appears at CCNP level.
Common mistakes and myths
- Mixing up the administrative distances (OSPF 110, EIGRP 90).
- Forgetting that OSPF areas must connect to area 0.
- Expecting EIGRP to run on non-Cisco devices.
Learn more
Key takeaways
- OSPF is open-standard link-state; EIGRP is Cisco advanced distance-vector.
- OSPF uses cost; EIGRP uses bandwidth and delay.
- EIGRP supports unequal-cost load balancing.
- CCNA focuses on OSPF.
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