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, and Ethernet and port-channel subinterfaces.

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

Diagram

Classes

nxos

Name	Type	Constraint	Mandatory	Default Value
devices	List	devices	No
device_groups	List	device_groups	No
global	Class	global	No
templates	List	templates	No
interface_groups	List	interface_groups	No

nxos

Name	Type	Constraint	Mandatory	Default Value
devices	List	devices	No
device_groups	List	device_groups	No
global	Class	global	No
templates	List	templates	No

devices (nxos)

Name	Type	Constraint	Mandatory	Default Value
configuration	Class	configuration	No

device_groups (nxos)

Name	Type	Constraint	Mandatory	Default Value
configuration	Class	configuration	No

global (nxos)

Name	Type	Constraint	Mandatory	Default Value
configuration	Class	configuration	No

templates (nxos)

Name	Type	Constraint	Mandatory	Default Value
configuration	Class	configuration	No

interface_groups (nxos)

Name	Type	Constraint	Mandatory	Default Value
configuration	Class	configuration	No

configuration (nxos.devices)

Name	Type	Constraint	Mandatory	Default Value
routing	Class	routing	No
interfaces	Class	interfaces	No

configuration (nxos.interface_groups)

Name	Type	Constraint	Mandatory	Default Value
subinterfaces	List	subinterfaces	No
ospf	Class	ospf	No

interfaces (nxos.devices.configuration)

Name	Type	Constraint	Mandatory	Default Value
loopbacks	List	loopbacks	No
vlans	List	vlans	No
ethernets	List	ethernets	No
port_channels	List	port_channels	No

ethernets (nxos.devices.configuration.interfaces)

Name	Type	Constraint	Mandatory	Default Value
subinterfaces	List	subinterfaces	No
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
subinterfaces	List	subinterfaces	No
ospf	Class	ospf	No

port_channels (nxos.devices.configuration.interfaces)

Name	Type	Constraint	Mandatory	Default Value
ospf	Class	ospf	No

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

subinterfaces (nxos.devices.configuration.interfaces.ethernets)

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
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	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	IP		No
default_information_originate	Boolean	true, false	No
default_information_originate_always	Boolean	true, false	No
default_information_originate_route_map	String		No
graceful_restart	Boolean	true, false	No
graceful_restart_grace_period	Integer	min: 5, max: 1800	No
graceful_restart_helper_disable	Boolean	true, false	No
graceful_restart_planned_only	Boolean	true, false	No
timers_throttle_spf_start_time	Integer	min: 1, max: 600000	No
timers_throttle_spf_hold_time	Integer	min: 1, max: 600000	No
timers_throttle_spf_max_time	Integer	min: 1, max: 600000	No
timers_throttle_lsa_start_time	Integer	min: 0, max: 5000	No
timers_throttle_lsa_hold_time	Integer	min: 50, max: 30000	No
timers_throttle_lsa_max_time	Integer	min: 50, max: 30000	No
timers_lsa_arrival	Integer	min: 10, max: 600000	No
timers_lsa_group_pacing	Integer	min: 1, max: 1800	No
max_metric_router_lsa	Class	max_metric_router_lsa	No
areas	List	areas	No
redistributions	List	redistributions	No
summary_addresses	List	summary_addresses	No
vrfs	List	vrfs	No

ospf_processes (nxos.devices.configuration.routing)

Name	Type	Constraint	Mandatory	Default Value
name	String		Yes
shutdown	Boolean	true, false	No
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	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	IP		No
max_metric_router_lsa	Class	max_metric_router_lsa	No
areas	List	areas	No
redistributions	List	redistributions	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
advertise_subnet	Boolean	true, false	No
area	Any	IP or Integer[min: 0, max: 4294967295]	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	point-to-point, broadcast	No
prefix_attributes_n_flag_clear	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	simple, md5, none	No

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

Name	Type	Constraint	Mandatory	Default Value
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	Default Value
id	Any	IP or Integer[min: 0, max: 4294967295]	Yes
authentication	Choice	simple, message-digest	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
ranges	List	ranges	No

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

Name	Type	Constraint	Mandatory	Default Value
id	Any	IP or Integer[min: 0, max: 4294967295]	Yes
authentication	Choice	simple, message-digest	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

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

Name	Type	Constraint	Mandatory	Default Value
protocol	Choice	static, direct, bgp, isis, ospf, ospfv3, eigrp, host, rip, amt, lisp, hmm, am, dhcpv6, icmpv6	Yes
protocol_instance	String		No
asn	Any	String or Integer[min: 0, max: 4294967295]	No
route_map	String		No

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

Name	Type	Constraint	Mandatory	Default Value
prefix	IP		Yes
not_advertise	Boolean	true, false	No
tag	Integer	min: 0, max: 4294967295	No

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

Name	Type	Constraint	Mandatory	Default Value
vrf	String		Yes
shutdown	Boolean	true, false	No
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	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	IP		No
default_information_originate	Boolean	true, false	No
default_information_originate_always	Boolean	true, false	No
default_information_originate_route_map	String		No
graceful_restart	Boolean	true, false	No
graceful_restart_grace_period	Integer	min: 5, max: 1800	No
graceful_restart_helper_disable	Boolean	true, false	No
graceful_restart_planned_only	Boolean	true, false	No
timers_throttle_spf_start_time	Integer	min: 1, max: 600000	No
timers_throttle_spf_hold_time	Integer	min: 1, max: 600000	No
timers_throttle_spf_max_time	Integer	min: 1, max: 600000	No
timers_throttle_lsa_start_time	Integer	min: 0, max: 5000	No
timers_throttle_lsa_hold_time	Integer	min: 50, max: 30000	No
timers_throttle_lsa_max_time	Integer	min: 50, max: 30000	No
timers_lsa_arrival	Integer	min: 10, max: 600000	No
timers_lsa_group_pacing	Integer	min: 1, max: 1800	No
max_metric_router_lsa	Class	max_metric_router_lsa	No
areas	List	areas	No
redistributions	List	redistributions	No
summary_addresses	List	summary_addresses	No

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

Name	Type	Constraint	Mandatory	Default Value
vrf	String		Yes
shutdown	Boolean	true, false	No
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	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	IP		No
max_metric_router_lsa	Class	max_metric_router_lsa	No
areas	List	areas	No
redistributions	List	redistributions	No

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

Name	Type	Constraint	Mandatory	Default Value
prefix	IP		Yes
not_advertise	Boolean	true, false	No
cost	Integer	min: 0, max: 16777215	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: point-to-point
            - id: 1/2
              ospf:
                process: "1"
                area: 0.0.0.0
                network: point-to-point

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: point-to-point
                hello_interval: 3
                dead_interval: 12
            - id: 1/2
              ospf:
                process: "1"
                area: 0.0.0.0
                network: point-to-point
                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: false

Example 5: OSPF with route redistribution

nxos:
  devices:
    - name: BORDER1
      configuration:
        routing:
          ospf_processes:
            - name: "1"
              router_id: 10.1.100.5
              areas:
                - id: 0.0.0.0
              redistributions:
                - protocol: static
                  route_map: STATIC_TO_OSPF
                - protocol: direct
                  route_map: DIRECT_TO_OSPF
                - protocol: bgp
                  asn: "65000"
                  route_map: BGP_TO_OSPF

Example 6: OSPF in VRF with redistributions

nxos:
  devices:
    - name: LEAF1
      configuration:
        routing:
          ospf_processes:
            - name: "100"
              vrfs:
                - vrf: TENANT_A
                  router_id: 10.1.100.3
                  areas:
                    - id: 0.0.0.0
                  redistributions:
                    - protocol: direct
                      route_map: DIRECT_TO_OSPF
                    - protocol: bgp
                      asn: "65001"
                      route_map: BGP_TO_OSPF_VRF

Example 7: OSPF with SPF/LSA throttling, graceful restart, default route origination, and summarization

nxos:
  devices:
    - name: BORDER1
      configuration:
        routing:
          ospf_processes:
            - name: "1"
              router_id: 10.1.100.5
              default_information_originate: true
              default_information_originate_always: true
              default_information_originate_route_map: DEFAULT_TO_OSPF
              graceful_restart: true
              graceful_restart_planned_only: true
              graceful_restart_grace_period: 120
              timers_throttle_spf_start_time: 50
              timers_throttle_spf_hold_time: 100
              timers_throttle_spf_max_time: 5000
              timers_throttle_lsa_start_time: 50
              timers_throttle_lsa_hold_time: 100
              timers_throttle_lsa_max_time: 5000
              timers_lsa_arrival: 100
              timers_lsa_group_pacing: 20
              areas:
                - id: 0.0.0.0
                - id: 0.0.0.10
                  ranges:
                    - prefix: 10.10.0.0/16
                      cost: 10
                    - prefix: 10.11.0.0/16
                      not_advertise: true
              summary_addresses:
                - prefix: 172.16.0.0/12
                  tag: 100
                - prefix: 192.168.0.0/16
                  not_advertise: true

Example 8: Point-to-point fabric uplink with OSPF key chain authentication

nxos:
  devices:
    - name: BORDER-LEAF1
      configuration:
        feature:
          ospf: true
        key_chains:
          - name: OSPF-UNDERLAY-AUTH
            keys:
              - id: 1
                key_string: OspfKey1
        routing:
          ospf_processes:
            - name: "1"
              areas:
                - id: 0.0.0.0
        interfaces:
          ethernets:
            - id: 1/48
              switchport:
                enabled: false
              ip:
                address: 10.1.10.0/31
              ospf:
                process: "1"
                area: 0.0.0.0
                network: point-to-point
                authentication: md5
                authentication_key_chain: OSPF-UNDERLAY-AUTH

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

Example 5: OSPF with route redistribution

nxos:
  devices:
    - name: BORDER1
      configuration:
        routing:
          ospf_processes:
            - name: "1"
              router_id: 10.1.100.5
              areas:
                - id: 0.0.0.0
              redistributions:
                - protocol: static
                  route_map: STATIC_TO_OSPF
                - protocol: direct
                  route_map: DIRECT_TO_OSPF
                - protocol: bgp
                  asn: "65000"
                  route_map: BGP_TO_OSPF

Example 6: OSPF in VRF with redistributions

nxos:
  devices:
    - name: LEAF1
      configuration:
        routing:
          ospf_processes:
            - name: "100"
              vrfs:
                - vrf: TENANT_A
                  router_id: 10.1.100.3
                  areas:
                    - id: 0.0.0.0
                  redistributions:
                    - protocol: direct
                      route_map: DIRECT_TO_OSPF
                    - protocol: bgp
                      asn: "65001"
                      route_map: BGP_TO_OSPF_VRF