Based on the provided reference from Palo Alto Networks, OSPF (Open Shortest Path First) uses IP protocol number 89.
The reference, titled "Ports Used for Routing," lists various routing protocols and the destination ports or IP protocol numbers they utilize.
OSPF Port Information from Reference
The relevant entry from the reference table is:
| Destination Port | Protocol | Description |
|---|---|---|
| 89 | IP | Port used for OSPF and OSPFv3. |
This indicates that OSPF does not use a traditional TCP or UDP port number in the same way applications do. Instead, it operates directly over IP using Protocol Number 89.
Understanding IP Protocol Numbers
Unlike applications like HTTP (TCP 80/443) or DNS (UDP/TCP 53) that use port numbers on top of TCP or UDP, some protocols, like OSPF and ICMP (Protocol 1), operate directly at the IP layer. These protocols are identified by an IP protocol number within the IP packet header, not a port number. OSPF is one such protocol, using the assigned IP protocol number 89.
For more details on ports used for routing protocols, you can refer to the Ports Used for Routing documentation on the Palo Alto Networks website.
