EIGRP or OSPF for an enterprise network, how do you choose?
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If the network is all Cisco, hub-and-spoke heavy and the team knows EIGRP, it is a fine choice: simple to configure, fast failover with feasible successors, summarization on any router, and stubs that keep branches out of the query domain. If the network is multivendor, or will connect firewalls, cloud routers and SD-WAN gear, I choose OSPF because everything speaks it. My default today is OSPF unless there is a reason for EIGRP.
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Side by side
| EIGRP | OSPF | |
|---|---|---|
| Vendor support | Cisco, plus RFC 7868 and a few open source stacks | Every router, firewall and cloud router |
| Visibility | Each router sees only neighbors' distances | Every router in an area has the full map |
| Hierarchy | None required; summarize anywhere | Areas, area 0 backbone, summarize at ABR or ASBR |
| Fast failover | Feasible successor, no messages | SPF rerun, fast with tuned timers and LFA |
| Failure mode to fear | Query storms and stuck in active | Flooding, LSDB size, area design mistakes |
| Metric | Bandwidth and delay | Cost from reference bandwidth |
What I would say about scale
Both scale to thousands of routers when designed well. EIGRP needs summarization and stubs to bound queries. OSPF needs areas and summarization to bound flooding and SPF work.
They will ask next
What would you choose for a service provider core?
IS-IS, or OSPF. Not EIGRP: providers need multivendor support, MPLS-TE and segment routing extensions, which are built around the link state protocols.
Traps
- Answering "EIGRP converges faster" with no conditions. It does only when a feasible successor exists.