OSPF (Open Shortest Path First) is an interior gateway protocol (IGP) that operates within a single autonomous system (AS). Starting with NSX 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.
Procedure
Results
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.