Technical Tip: Maximum number of OSPF neighbors
Description
This article discusses the maximum number of OSPF neighbors allowed in FortiOS.
Scope
FortiGate.
Solution
The limit of a maximum number of 10 per VDOM, which is as stated in the Maximum Value table for version 4.3, 5.0.x, 5.2.x, is restricted only to the statically configured neighbors, that is, in 'config neighbor'. However, OSPF was designed in a way to be highly scalable without requiring manual neighbor configuration.
The parameter to search for is 'router.ospf:neighbor'. Refer to the Maximum Value Table
For OSPF dynamic neighbors, there is no hard-coded limitation in FortiOS like for static neighbors. Static OSPF neighbors are a configurable parameter; dynamic neighbors are not.
The limit of dynamic neighbors is more related to the operational status of the FortiGate and is dictated by factors such as:
- Amount of available memory on the low-end and high-end devices.
- Traffic load of the unit.
- Number of features used (For example: UTM, VPN, other routing protocols).
- Size of the OSPF routes provided by the neighbors.
- OSPF link state database.
A maximum of 10 static neighbors can be configured in the CLI, as in the example below:
config router ospf
config neighbor
edit 1 <---- Limitation to a maximum of 10 neighbors applies.
set ip 192.168.21.63 <---- Example neighbor IP.
end
end
The relevant CLI Reference guides available in the Fortinet Document Library provide further information.