How does internet deliver without reserving a path first?
Per Wikipedia: “A datagram network treats each packet independently; each may take different path, no setup, no reservation.”
Like postcards — each mailed alone, may take different trucks, receiver reorders if needed.
- App slices message into datagrams
- Each stamped with destination
- Routers forward independently
- May arrive out of order
- Destination reassembles
- No setup delay
- Robust — alternate paths if link fails
- No bandwidth guarantee
- Needs sequence numbers
IP forwarding per packet- Built from: Packet Switching — datagram is packet switching style
- Contrasts with: Circuit Switching — circuit fixes path
- Related: Store-and-Forward — datagrams use store-forward
- Related: Broadcast Links — both are best-effort
- Assuming ordered delivery — datagrams not ordered
- Thinking connection needed — datagram is connectionless