OSPF

OSPF (Open Shortest Path First) is a standards-based link-state interior gateway protocol that uses Dijkstra’s shortest path first algorithm to calculate optimal routes within an autonomous system, supporting VRF-aware multi-instance deployments on NX-OS. It provides hierarchical network design through area-based segmentation with configurable area types (stub, NSSA), route summarization, max-metric advertisement for graceful maintenance, and advanced features like BFD integration for fast failure detection. OSPF interface-level configuration controls process association, area membership, cost, network type, priority, authentication, and passive interface behavior across loopback, VLAN, Ethernet, and port-channel interfaces.

Diagram

Classes

routing (nxos.devices.configuration)

Name	Type	Constraint	Mandatory	Default Value
ospf_processes	List	`[ospf_processes]`	No

loopbacks (nxos.devices.configuration.interfaces)

Name	Type	Constraint	Mandatory	Default Value
ospf	Class	`[ospf]`	No

vlans (nxos.devices.configuration.interfaces)

Name	Type	Constraint	Mandatory	Default Value
ospf	Class	`[ospf]`	No

ethernets (nxos.devices.configuration.interfaces)

Name	Type	Constraint	Mandatory	Default Value
ospf	Class	`[ospf]`	No

port_channels (nxos.devices.configuration.interfaces)

Name	Type	Constraint	Mandatory	Default Value
ospf	Class	`[ospf]`	No

ospf_processes (nxos.devices.configuration.routing)

Name	Type	Constraint	Mandatory	Default Value
name	String		Yes
shutdown	Boolean	`true`, `false`	No	`false`
auto_cost_reference_bandwidth	Integer	min: `0`, max: `4294967295`	No
auto_cost_reference_bandwidth_unit	Choice	`mbps`, `gbps`	No
bfd	Boolean	`true`, `false`	No
capability_vrf_lite	Choice	`unspecified`, `l3vpn`, `evpn`	No
default_metric	Integer	min: `0`, max: `16777214`	No
passive_interface_default	Boolean	`true`, `false`	No
default_route_nssa_abr_pbit_clear	Boolean	`true`, `false`	No
discard_route_external	Boolean	`true`, `false`	No
discard_route_internal	Boolean	`true`, `false`	No
distance	Integer	min: `1`, max: `255`	No
down_bit_ignore	Boolean	`true`, `false`	No
log_adjacency_changes	Choice	`none`, `brief`, `detail`	No
maximum_paths	Integer	min: `1`, max: `64`	No
name_lookup	Boolean	`true`, `false`	No
name_lookup_use_vrf	String		No
rfc1583compatibility	Boolean	`true`, `false`	No
router_id	String		No
max_metric_router_lsa	Class	`[max_metric_router_lsa]`	No
areas	List	`[areas]`	No
vrfs	List	`[vrfs]`	No

ospf (nxos.devices.configuration.interfaces.loopbacks)

Name	Type	Constraint	Mandatory	Default Value
process	String		Yes
advertise_secondaries	Boolean	`true`, `false`	No	`true`
advertise_subnet	Boolean	`true`, `false`	No
area	String		No
bfd	Boolean	`true`, `false`	No
cost	Integer	min: `0`, max: `65535`	No
dead_interval	Integer	min: `0`, max: `65535`	No
hello_interval	Integer	min: `0`, max: `65535`	No
mtu_ignore	Boolean	`true`, `false`	No
network	Choice	`unspecified`, `p2p`, `bcast`	No
prefix_attribute_n_flag	Choice	`unspecified`, `clear`	No
passive_interface	Boolean	`true`, `false`	No
priority	Integer	min: `0`, max: `255`	No
retransmit_interval	Integer	min: `1`, max: `65535`	No
transmit_delay	Integer	min: `1`, max: `450`	No
authentication_key	String		No
message_digest_key_id	Integer	min: `0`, max: `255`	No
authentication_key_secure_mode	Boolean	`true`, `false`	No
authentication_key_chain	String		No
message_digest_key	String		No
message_digest_key_secure_mode	Boolean	`true`, `false`	No
authentication	Choice	`unspecified`, `simple`, `md5`, `none`	No

max_metric_router_lsa (nxos.devices.configuration.routing.ospf_processes)

Name	Type	Constraint	Mandatory
on_startup_wait_for_bgp	String		No
external_lsa	Boolean	`true`, `false`	No
external_lsa_max_metric	Integer	min: `0`, max: `16777215`	No
include_stub	Boolean	`true`, `false`	No
summary_lsa	Boolean	`true`, `false`	No
summary_lsa_max_metric	Integer	min: `0`, max: `16777215`	No
on_startup	Boolean	`true`, `false`	No
on_startup_timeout	Integer	min: `0`, max: `4294967295`	No

areas (nxos.devices.configuration.routing.ospf_processes)

Name	Type	Constraint	Mandatory
id	String		Yes
authentication	Choice	`unspecified`, `simple`, `md5`, `none`	No
default_cost	Integer	min: `0`, max: `16777215`	No
nssa_no_redistribution	Boolean	`true`, `false`	No
no_summary	Boolean	`true`, `false`	No
nssa_translate_type7	Choice	`always`, `candidate`, `never`	No
segment_routing_mpls	Boolean	`true`, `false`	No
nssa_translate_type7_suppress_fa	Boolean	`true`, `false`	No
type	Choice	`regular`, `stub`, `nssa`	No

vrfs (nxos.devices.configuration.routing.ospf_processes)

Name	Type	Constraint	Mandatory	Default Value
vrf	String		Yes
shutdown	Boolean	`true`, `false`	No	`false`
auto_cost_reference_bandwidth	Integer	min: `0`, max: `4294967295`	No
auto_cost_reference_bandwidth_unit	Choice	`mbps`, `gbps`	No
bfd	Boolean	`true`, `false`	No
capability_vrf_lite	Choice	`unspecified`, `l3vpn`, `evpn`	No
default_metric	Integer	min: `0`, max: `16777214`	No
passive_interface_default	Boolean	`true`, `false`	No
default_route_nssa_abr_pbit_clear	Boolean	`true`, `false`	No
discard_route_external	Boolean	`true`, `false`	No
discard_route_internal	Boolean	`true`, `false`	No
distance	Integer	min: `1`, max: `255`	No
down_bit_ignore	Boolean	`true`, `false`	No
log_adjacency_changes	Choice	`none`, `brief`, `detail`	No
maximum_paths	Integer	min: `1`, max: `64`	No
name_lookup	Boolean	`true`, `false`	No
name_lookup_use_vrf	String		No
rfc1583compatibility	Boolean	`true`, `false`	No
router_id	String		No
max_metric_router_lsa	Class	`[max_metric_router_lsa]`	No
areas	List	`[areas]`	No

Examples

Example 1: Basic OSPF underlay for spine-leaf fabric with loopback and P2P links

nxos:
  devices:
    - name: LEAF1
      configuration:
        routing:
          ospf_processes:
            - name: "1"
              router_id: 10.1.100.3
              areas:
                - id: 0.0.0.0
        interfaces:
          loopbacks:
            - id: 0
              ospf:
                process: "1"
                area: 0.0.0.0
            - id: 1
              ospf:
                process: "1"
                area: 0.0.0.0
          ethernets:
            - id: 1/1
              ospf:
                process: "1"
                area: 0.0.0.0
                network: p2p
            - id: 1/2
              ospf:
                process: "1"
                area: 0.0.0.0
                network: p2p

Example 2: OSPF with BFD, tuned timers, and passive interfaces

nxos:
  devices:
    - name: SPINE1
      configuration:
        routing:
          ospf_processes:
            - name: "1"
              router_id: 10.1.100.1
              bfd: true
              log_adjacency_changes: detail
              areas:
                - id: 0.0.0.0
        interfaces:
          loopbacks:
            - id: 0
              ospf:
                process: "1"
                area: 0.0.0.0
            - id: 100
              ospf:
                process: "1"
                area: 0.0.0.0
          ethernets:
            - id: 1/1
              ospf:
                process: "1"
                area: 0.0.0.0
                network: p2p
                hello_interval: 3
                dead_interval: 12
            - id: 1/2
              ospf:
                process: "1"
                area: 0.0.0.0
                network: p2p
                hello_interval: 3
                dead_interval: 12

Example 3: Multi-area OSPF with stub area and max-metric for maintenance

nxos:
  devices:
    - name: BORDER-LEAF1
      configuration:
        routing:
          ospf_processes:
            - name: "1"
              router_id: 10.1.100.3
              log_adjacency_changes: brief
              maximum_paths: 8
              rfc1583compatibility: false
              max_metric_router_lsa:
                on_startup: true
                on_startup_timeout: 600
                external_lsa: true
                summary_lsa: true
              areas:
                - id: 0.0.0.0
                - id: 0.0.0.10
                  type: stub
                  default_cost: 10
                  no_summary: true

Example 4: OSPF in a VRF with passive-interface default and interface overrides

nxos:
  devices:
    - name: LEAF1
      configuration:
        routing:
          ospf_processes:
            - name: "1"
              router_id: 10.1.100.3
              areas:
                - id: 0.0.0.0
            - name: "100"
              vrfs:
                - vrf: BLUE
                  router_id: 10.1.100.3
                  passive_interface_default: true
                  auto_cost_reference_bandwidth: 100
                  auto_cost_reference_bandwidth_unit: gbps
                  areas:
                    - id: 0.0.0.0
        interfaces:
          vlans:
            - id: 1010
              vrf: BLUE
              ospf:
                process: "100"
                area: 0.0.0.0
                passive_interface: disabled