OSPFv2

netverdict models OSPFv2 as a deterministic routing protocol, not as a vendor router binary. The goal is to answer practical questions:

Will these routers form neighbours?
Which router becomes DR or BDR?
Which routes are intra-area, inter-area, or external?
What changes when an ABR summarizes, a stub area blocks externals, or a virtual link is added?

Support level

Area	Level	What this means
Single-area OSPFv2	Supported	Neighbours, router IDs, OSPF routes, interface costs, timers, passive interfaces.
Multi-area OSPFv2	Supported	ABR detection, area 0 backbone rules, Type-3 inter-area route projection.
Broadcast segments	Supported	DR / BDR election with priority and router-id tie-breaks.
Stub areas	Supported	Stub and totally-stubby behaviour, including ABR default route injection.
NSSA	Supported	NSSA and totally-NSSA route behaviour, including Type-7-style local external handling and ABR projection.
ABR summarisation	Supported	`area <id> range`, `not-advertise`, and cost override.
Virtual links	Supported	ABR-to-ABR logical area-0 adjacency through a non-stub transit area.
Static redistribution	Supported	Static routes become OSPF external routes; E1 / E2 metric type is tracked.
OSPF authentication	Partial	MD5 configuration is parsed and adjacency mismatch is modelled. Packet-level cryptographic fidelity is not the goal.
Packet fidelity	Partial	PCAP export writes OSPFv2 Hello and LSU-shaped packets. The simulator does not replay every LSA exchange packet.

Standards coverage

Standard	Coverage	Notes
RFC 2328, OSPF Version 2	Behaviour model	Core OSPFv2 concepts: areas, router IDs, Hello timers, DR / BDR election, SPF route computation, Type-3 summaries, virtual links, external routes.
RFC 2328 section 9.4	Supported	DR / BDR election uses priority first and router ID as deterministic tie-break. Priority `0` prevents DR / BDR eligibility.
RFC 2328 section 12.4.3	Supported	ABR summary range behaviour for `area <id> range`: covered components are suppressed and one summary may be advertised.
RFC 2328 section 15.1	Supported	Virtual links are validated against ABR and transit-area constraints. Stub-family transit areas are rejected.
RFC 2328 appendix D	Partial	Area and interface MD5 authentication settings are accepted. Authentication mismatch prevents adjacency.
RFC 3101, NSSA	Behaviour model	NSSA and totally-NSSA area types are modelled for routing behaviour.
RFC 5880, BFD	Integration	OSPF can be gated by BFD with `ip ospf bfd` or `bfd all-interfaces`. BFD itself is modelled separately.
RFC 5340, OSPFv3	Separate page	OSPFv3 exists as a separate IPv6 model and is not covered by this OSPFv2 matrix.

Feature matrix

Feature	Status	Notes
`router ospf <pid>`	Supported	One process per device in the global VRF.
Router ID selection	Supported	Explicit `router-id`; otherwise highest interface IP at startup.
`network <prefix> <wildcard> area <id>`	Supported	Cisco-style network statements bind IPv4 interfaces to areas.
Dotted area IDs	Supported	Accepted in Cisco-style CLI where implemented.
Hello packets	Supported	Simulated on deterministic timers, not wall-clock timers.
Hello / dead timer mismatch	Supported	Mismatched neighbours do not form; mismatch is surfaced as an event.
Passive interfaces	Supported	`passive-interface <name>` and `passive-interface default`.
Interface cost	Supported	`ip ospf cost <cost>` participates in route computation.
Interface priority	Supported	`ip ospf priority <0-255>` controls DR / BDR election.
DR / BDR election	Supported	Deterministic election on broadcast multi-access segments.
Point-to-point adjacency	Supported	Modelled through shared links and interface area membership.
Router LSAs	Behaviour model	Internal LSDB state is modelled for route computation and show output.
Network LSAs	Behaviour model	Broadcast transit segments are represented for SPF behaviour.
Summary LSAs	Behaviour model	Type-3 inter-area route projection is modelled at ABRs.
External LSAs	Behaviour model	Redistributed statics are projected as external routes.
E1 / E2 metric type	Supported	`redistribute static metric-type 1` or `2`; E2 is the default.
Stub area	Supported	Blocks external routes and injects a default from the ABR.
Totally-stubby area	Supported	Blocks external and inter-area routes; default remains.
NSSA	Supported	Allows local external injection while preserving stub-like area behaviour.
Totally-NSSA	Supported	NSSA plus inter-area suppression.
Area default cost	Supported	`area <id> default-cost <cost>` changes the injected default metric.
Area range	Supported	`area <id> range <network> <mask>`.
Area range `not-advertise`	Supported	Suppresses covered prefixes and does not emit the summary.
Area range `cost`	Supported	Explicit summary cost override.
Virtual links	Supported	`area <transit> virtual-link <remote-router-id>`.
Virtual-link cost	Supported	Optional explicit cost.
Virtual-link auth mode	Configured	Accepted and emitted; packet-level auth exchange is simplified.
`maximum-paths`	Supported	Limits equal-cost OSPF paths installed into the RIB.
`default-information originate`	Supported	Advertises a default route when enabled. Optional `always` is accepted as equivalent.
`auto-cost reference-bandwidth`	Stored	Accepted and emitted. Current route calculation still relies on configured/static interface costs.
`redistribute bgp ...`	Import fidelity	Grammar is accepted for imported configs; behaviour focus is static redistribution today.
Graceful restart	Not modelled	Planned for later production-behaviour coverage.
Opaque LSAs / traffic engineering	Not modelled	Not part of the current OSPF training surface.

Vendor command matrix

Command	IOS-style	Junos-style	VyOS-style	Notes
`router ospf 1`	Supported	n/a	n/a	Cisco-family process mode.
`router-id 1.1.1.1`	Supported	Supported	Supported	Junos / VyOS map to the same canonical OSPF router ID.
`network 10.0.0.0 0.0.0.255 area 0`	Supported	n/a	n/a	Cisco-style interface selection.
`set protocols ospf area 0 interface ge-0/0/0`	n/a	Supported	n/a	Junos-style interface-to-area binding.
`set protocols ospf area 0 interface ge-0/0/0 metric 25`	n/a	Supported	n/a	Commits into canonical interface OSPF cost.
`set protocols ospf area 0 interface ge-0/0/0 hello-interval 5`	n/a	Supported	n/a	Commits into canonical hello timer.
`set protocols ospf area 0 interface ge-0/0/0 dead-interval 20`	n/a	Supported	n/a	Commits into canonical dead timer.
`set protocols ospf area 0 interface ge-0/0/0 priority 0`	n/a	Supported	n/a	Commits into DR/BDR priority.
`set protocols ospf area 0 interface ge-0/0/0 passive`	n/a	Supported	n/a	Adds interface to passive OSPF set.
`set protocols ospf area 0 interface ge-0/0/0 bfd-liveness-detection`	n/a	Supported	n/a	Enables OSPF BFD gating.
`set protocols ospf area 0 network 10.0.0.0/24`	n/a	n/a	Supported	VyOS-style area network syntax.
`passive-interface default`	Supported	Partial	Supported	Canonical passive-default is supported; vendor surfaces vary.
`passive-interface GigabitEthernet0/0`	Supported	Partial	Supported	Vendor import maps to canonical passive interfaces where available.
`ip ospf priority 200`	Supported	n/a	n/a	Controls DR / BDR election.
`ip ospf cost 20`	Supported	Partial	Partial	Canonical interface cost is supported; vendor syntax differs.
`ip ospf hello-interval 5`	Supported	Not yet	Not yet	Cisco-style per-interface timer override.
`ip ospf dead-interval 20`	Supported	Not yet	Not yet	Must be greater than hello interval.
`ip ospf message-digest-key 1 md5 secret`	Partial	Not yet	Not yet	Auth mismatch affects adjacency; cryptographic packet fidelity is simplified.
`area 1 stub`	Supported	Not yet	Supported	Blocks Type-5 external routes and injects default.
`area 1 stub no-summary`	Supported	Not yet	Not yet	Totally-stubby behaviour.
`area 1 nssa`	Supported	Not yet	Supported	NSSA route behaviour is modelled.
`area 1 nssa no-summary`	Supported	Not yet	Not yet	Totally-NSSA behaviour.
`area 1 range 10.0.0.0 255.255.0.0`	Supported	Not yet	Not yet	ABR Type-3 summarisation.
`area 1 virtual-link 2.2.2.2`	Supported	Not yet	Not yet	Logical area-0 adjacency through transit area.
`redistribute static`	Supported	Partial	Supported	Static redistribution into OSPF.
`redistribute static route-map NAME`	Supported	Not yet	Not yet	Route-map can filter redistributed static routes.
`bfd all-interfaces`	Supported	Not yet	Not yet	Enables BFD gating for all OSPF interfaces.
`ip ospf bfd`	Supported	Not yet	Not yet	Enables BFD gating per interface.
`show ip ospf`	Supported	Supported view	n/a	Shows process and area state from canonical runtime.
`show ip ospf neighbor`	Supported	Supported view	Supported	Neighbour table from runtime state.
`show ip ospf database`	Supported	Supported view	n/a	LSDB-oriented view.
`show ip ospf border-routers`	Supported	n/a	n/a	ABR / ASBR visibility.
`show ip ospf virtual-links`	Supported	n/a	n/a	Virtual-link state and reason when down.

Behaviour notes

OSPF in netverdict is replay-oriented. Timers are simulated events, not wall-clock sleeps. Running the same topology and the same commands should produce the same neighbour states and route tables.

SPF is deterministic. When multiple equal-cost candidates exist, the engine uses stable ordering so a replay does not drift between runs.

Broadcast network DR / BDR election follows the OSPF priority rule first, then router ID. The bundled DR lab deliberately uses router IDs 1.1.1.1, 2.2.2.2, and 3.3.3.3 so the default outcome is easy to inspect before changing priority.

ABR summarisation is modelled at the area boundary. With area 1 range 10.0.0.0 255.255.0.0, more-specific area-1 components are suppressed when leaving area 1, and the ABR emits the configured summary unless not-advertise is present.

Virtual links are modelled as logical area-0 links between ABRs. They require a valid non-stub transit area. If the transit area is stub-family, the virtual link stays down and show ip ospf virtual-links reports the reason.

Examples

Basic single-area OSPF

configure terminal
router ospf 1
 router-id 1.1.1.1
 network 10.0.12.0 0.0.0.3 area 0
 network 1.1.1.1 0.0.0.0 area 0
end
show ip ospf neighbor
show ip route

Vendor styles

IOS-style

router ospf 1
 router-id 1.1.1.1
 network 10.0.12.0 0.0.0.3 area 0
 network 10.0.1.0 0.0.0.255 area 1
 area 1 stub no-summary

Junos-style

set routing-options router-id 1.1.1.1
set protocols ospf area 0 interface ge-0/0/0.0
set protocols ospf area 1 stub
set protocols ospf area 1 interface ge-0/0/1.0

VyOS-style

set protocols ospf parameters router-id 1.1.1.1
set protocols ospf area 0 network 10.0.12.0/30
set protocols ospf area 1 network 10.0.1.0/24
set protocols ospf area 1 area-type stub

Force a DR election outcome

configure terminal
interface GigabitEthernet0/0
 ip ospf priority 200
end
clear ip ospf process
show ip ospf neighbor

Summarise area routes at an ABR

configure terminal
router ospf 1
 area 1 range 10.0.0.0 255.255.0.0
end
show ip ospf database
show ip route

Build a virtual link through area 1

On the ABR connected to area 0:

configure terminal
router ospf 1
 area 1 virtual-link 3.3.3.3
end
show ip ospf virtual-links

On the remote ABR:

configure terminal
router ospf 1
 area 1 virtual-link 2.2.2.2
end
show ip ospf virtual-links

Runnable labs

Lab	Covers	Link
OSPF DR / BDR election	Broadcast segments, priority, router-id tie-break	Open lab
OSPF multi-area ABR	Area 0, non-zero areas, ABR Type-3 projection	Open lab
OSPF area range	ABR summarisation with `area <id> range`	Open lab
OSPF virtual link	Logical area-0 adjacency through transit area	Open lab

Known limits

netverdict intentionally separates routing behaviour from full packet-level vendor emulation.

The current OSPFv2 model does not implement graceful restart, opaque LSAs, traffic-engineering LSAs, vendor-specific SPF throttling, or exact vendor debug output. PCAP export is useful for inspection, but it is not a guarantee that every byte matches a specific router release.

Use the page as a support contract for the simulator, not as a claim that netverdict is a drop-in replacement for IOS, Junos, FRR, or VyOS.