📡 Routing vs Forwarding

1. Routing

• Definition: The decision-making process of determining the best path for data packets to travel across a network.
• Who does it: Routers (using routing tables and protocols).
• Key points:
  • Involves building and maintaining a routing table.
  • Uses routing protocols (e.g., RIP, OSPF, BGP) to exchange information with other routers.
  • Considers metrics like hop count, bandwidth, latency, and policy.
• Analogy: Like planning a road trip — choosing which highways and roads to take before you start driving.

2. Forwarding

• Definition: The actual act of sending a packet from one interface to another, based on the routing table’s decision.
• Who does it: Routers and switches.
• Key points:
  • Uses the forwarding table (derived from the routing table).
  • Happens at high speed, often in hardware (ASICs).
  • Focuses only on moving the packet to the next hop.
• Analogy: Like driving along the chosen road — once the route is decided, forwarding is just following it.

3. Relationship

• Routing = thinking (deciding the path).
• Forwarding = doing (sending the packet along that path).
• Routing is control‑plane logic; forwarding is data‑plane action.

4. Example

• You send a message from your laptop in Manila to a server in New York.
  • Routing: Routers decide the best path across the Internet (via Hong Kong → Los Angeles → New York).
  • Forwarding: Each router along the way physically passes the packet to the next router according to the chosen path.

✅ Summary

• Routing = decision process (control plane).
• Forwarding = packet delivery (data plane). Together, they ensure data travels efficiently across networks