Network layers want to forward packets as fast as possible without the overhead of guaranteeing delivery. Some services (like IP) prioritize speed and simplicity over reliability.
A delivery model where the network makes its “best effort” to deliver packets but provides no guarantees — packets can be lost, duplicated, or arrive out of order.
- Network layer receives packet from transport layer
- Attempts to route and forward packet toward destination
- If link is congested or error occurs: packet may be dropped
- No acknowledgments, retransmissions, or error recovery at this layer
- Higher layers (e.g., TCP) must handle reliability if needed
- No delivery guarantees
- No order guarantees
- No error recovery (just detection via checksums)
- Minimal overhead — fast and simple
- Built from: IP Protocol — uses best-effort delivery
- Built from: Connectionless Service — inherently best-effort
- Contrasts with: Reliable Data Transfer — guarantees vs no guarantees
- Related: UDP — transport layer best-effort protocol
- Higher layers must implement reliability if needed (TCP does this on top of IP)
- Packet loss is expected and must be handled by applications or transport layer
- “Best effort” doesn’t mean “no effort” — routers still try their best to forward