OSPF (Open Shortest Path First) is an interior gateway protocol (IGP) that operates within a single autonomous system (AS). Starting with NSX-T Data Center 3.1.1, you can configure OSPF on a tier-0 gateway.

The OSPF feature has the following capabilities and restrictions:
  • Only OSPFv2 is supported.
  • The tier-0 gateway can be active-active or active-standby (preemptive and non-preemptive).
  • Only the default VRF is supported.
  • You can configure a single area on a tier-0 gateway with a maximum of two tier-0 uplinks per Edge node.
  • Backbone, normal area, and NSSA (not-so-stubby area) are supported.
  • No redistribution is supported between BGP and OSPF.
  • OSPF and BGP can be used together in the case of BGP multi-hop where the peer IP is learned through OSPF.
  • The same redistribution features supported for BGP are supported for OSPF (tier-0 uplinks, downlinks, loopbacks, tier-1 downlinks, etc.). Depending on the area type, redistribution for all these networks will result in the Edge node generating type 5 external LSA (link-state advertisement) or type 7 external LSA with type 2 metric only (e2 or n2 routes). The Edge node itself can learn any type of LSA.
  • MD5 and plain password authentication are supported on the area configuration.
  • Federation is not supported.
  • Route summarization for e2 and n2 routes is supported.
  • The interface running OSPF can be broadcast or numbered point-to-point (/31).
  • OSPF sessions can be backed with BFD.
  • For graceful restart, only the helper mode is supported.
  • Redistribution route maps are supported. Only the matching of prefix lists is applicable. No set actions.
  • OSPF ECMP is supported up to maximum of 8 paths.
  • Default Originate is supported.
  • NAT with OSPF is not supported.
  • Tier-0 VIP with OSPF is not supported.
How the OSPF router ID (RID) is determined:
  • If there is no loopback interface, OSPF takes the highest interface IP address as RID.
  • If OSPF has already chosen the highest interface IP as RID, adding a loopback interface will not affect OSPF neighborship and RID is not changed.
  • If RID is the highest interface IP and loopback is present, disabling and enabling OSPF will change the RID to the loopback IP.
  • If RID is the highest interface IP and loopback is present, rebooting the edge node, enabling maintenance mode on the edge node, or restarting the routing process will not change the RID.
  • If RID is the highest interface IP and loopback is present, redeploying or replacing the edge transport node will change the RID to the loopback interface IP.
  • If RID is the highest interface IP and loopback is present, modifying or deleting the highest interface IP address will change the RID to the loopback interface IP.
  • If RID is the loopback interface IP, modifying or deleting the highest interface IP will not change the RID.
  • Clearing OSPF neighbors will change the RID. It retains only the old RID.
  • A soft restart or hard restart of OSPF adjacency from a remote site does not affect the OSPF RID.


  1. With admin privileges, log in to NSX Manager.
  2. Select Networking > Tier-0 Gateways.
  3. Click the OSPF toggle to enable OSPF.
  4. In the Area Definition field, click Set to add an area definition.
    You can add only one area definition.
    1. Click Add Area Definition.
    2. Enter an area ID.
      The value must be a number or 4 numbers in IPv4 format (for example,
    3. In the Type column, select Normal or NSSA.
      An OSPF NSSA (not-so-stubby area) allows external routes to be flooded within the area.
    4. In the Authentication column, select None, Password, or MD5.
    5. In the Key ID column, enter a key ID if Authentication is set to MD5.
    6. In the Password column, enter a password if Authentication is set to Password or MD5.
      In NSX-T Data Center and earlier, the plain-text and MD5 passwords can have a maximum of 8 characters. Starting with NSX-T Data Center, the MD5 password can have a maximum of 16 characters, and the maximum length of the plain-text password remains to be 8 characters.
    7. Click Save.
  5. In the Graceful Restart field, select either Disable or Helper Only.
  6. Click the ECMP toggle to enable or disable ECMP.
    ECMP (equal-cost multi-path) routing allows packet forwarding to occur over multiple best paths. It can provide fault tolerance for failed paths.
  7. In the Route Summarization field, click Set to add a summary address.
    Route summarization can reduce the number of LSAs that are flooded into an area. You can summarize one or more ranges of IP addresses and send routing information about these addresses in a single LSA.
    1. Click Add Prefix.
    2. Enter an IP address prefix in CIDR format.
    3. In the Advertise column, select Yes or No to indicate whether to advertise the summary route.
      The default is Yes.
    4. Repeat the steps above to add more prefixes.
  8. Click the Default Route Originate toggle to enable or disable default route originate.
    Enable this to redistribute the default route in OSFP.
  9. In the OSPF Configured Interfaces field, click Set to configure OSPF on existing external interfaces.
    1. Click Configure Interface.
    2. In the Interface column, select an interface from the dropdown list.
    3. In the Area ID column, select an area ID from the dropdown list.
    4. In the Network Type column, select Broadcast or P2P.
    5. In the OSPF column, set the toggle to Enabled.
    6. Click the BFD toggle to enable or disable BFD.
    7. If BFD is enabled, select a BFD profile.
    8. To change the OSPF Hello Interval, enter a new value.
      The default is 10 seconds. This parameter specifies the time between Hello messages.
    9. To change the OSPF Dead Interval, enter a new value.
      The default is 40 seconds. If a Hello message is not received within this time interval, the neighbor is considered unavailable..
    10. Click Save.
    11. Repeat the steps above to configure more interfaces.
  10. Click Save.
  11. Click Route Re-distribution to expand the section.
  12. Click the OSPF Route Redistribution Status toggle to enable OSPF.
  13. If you have route re-distribution rules configured, click the number to see the current rules or to add additional ones. If you do not have any configured, click Set to add re-distribution rules. Add OSPF to the Destination Protocol of any rule that will redistribute routes into OSPF. Remember to do this step if you plan to add re-distribution rules later.


After you configure OSPF, in the OSPF Neighbors field, you can click View to see information about OSPF neighbors. The information displayed includes Neighbor IP Address, Interface, Source, Edge Node, Priority, and State.

Note: If a neighbor is not reachable, an alarm about the neighbor will be raised. If the neighbor is no longer in the network, simply acknowledge the alarm but do not resolve it. If you resolve the alarm, it will be raised again.