Arista EOS OSPF Configuration

What is it?

Arista OSPF uses per-interface configuration (like Juniper) rather than Cisco IOS 'network' statements. Interfaces are added directly with 'ip ospf <process-id> area <area>' on the interface. BFD (Bidirectional Forwarding Detection) integration is a key Arista advantage — it is a tiny hello protocol that runs beside OSPF and notices a dead link in milliseconds, cutting convergence from 40 seconds (the OSPF dead timer) to under one second. EOS gives you two separate knobs for it and they are not the same thing: 'bfd default' under 'router ospf' turns BFD on for every OSPF interface in that instance, while 'ip ospf bfd' on an interface turns it on for that one link only. This generator asks which model you want, because the choice matters: 'bfd default' is one line and cannot be forgotten on a new link, but it also lights up BFD on interfaces where you may not want it — a slow WAN circuit, or a vEOS lab link that will flap. In that case stay on the instance default and switch the exception off with 'no ip ospf bfd'. Arista OSPF is the standard underlay IGP for VXLAN EVPN data center fabrics.

How it compares

Prerequisites

• →Interfaces must have IP addresses configured before enabling OSPF
• →Loopback interface should be configured and added to OSPF as passive
• →Router ID should be set to a stable loopback address
• →For VXLAN EVPN fabric: use 'ip ospf network point-to-point' on fabric links to avoid DR/BDR election
• →BFD must be enabled on BOTH ends of a link. One side alone leaves the session in Down and OSPF keeps using its own 40-second dead timer, so you get the configuration without the convergence
• →EOS 4.15 or later for OSPF BFD integration ('bfd default' and 'ip ospf bfd')

Config Generator

Verification commands

Debug commands

Common mistakes & fixes

Related configs