OSPF (Open Shortest Path First) is a Layer 3 protocol. It operates at the network layer of the OSI model.
OSPF is a dynamic routing protocol that uses link-state information to make routing decisions within a single Autonomous System (AS). Here's why it's a Layer 3 protocol:
- Operates on IP Addresses: OSPF relies on IP addresses for identifying networks and routers. It doesn't deal with port numbers like Layer 4 protocols (TCP/UDP).
- Routing Decisions: It's primary function is to determine the best path for data packets based on IP addresses, which is a Layer 3 responsibility.
- Uses IP Protocol: OSPF packets are encapsulated directly within IP packets, specifically using IP protocol number 89. It doesn't use TCP or UDP for communication.
In summary, OSPF works at the network layer by exchanging routing information using IP addressing. It is, therefore, a Layer 3 protocol.
