Network communication needs reliable, ordered delivery for applications like web browsing and file transfers. Without a connection-oriented approach, data might arrive out of order, get lost, or overwhelm receivers.
A service that establishes a dedicated logical connection between sender and receiver before exchanging data, guaranteeing reliable, ordered delivery with flow and congestion control.
- A connection establishment phase occurs using a handshake (e.g., TCP three-way handshake: SYN, SYN-ACK, ACK)
- Both endpoints maintain state information including sequence numbers, acknowledgments, and buffer sizes
- Data is delivered reliably with guaranteed ordering, error checking, and retransmission of lost packets
- Flow control prevents fast senders from overwhelming slow receivers
- Congestion control manages network traffic to prevent bottlenecks
- A teardown phase releases the connection when communication ends
- Guaranteed delivery through retransmission of lost packets
- Ordered delivery preserving send sequence
- Stateful: both endpoints maintain connection state
- Higher overhead due to setup, maintenance, and reliability mechanisms
- Uses a logical path (virtual circuit) for the connection duration
- Built from: Three-Way Handshake — connection establishment mechanism
- Built from: Reliable Data Transfer — core guarantee provided
- Builds into: TCP — primary protocol implementing this service
- Contrasts with: Connectionless Service — no setup or reliability guarantees
- Related: Flow Control — prevents receiver overload
- Related: Congestion Control — manages network bottlenecks
- Higher latency due to connection setup overhead
- State maintenance consumes memory on both endpoints
- Connection state can be lost during network failures requiring re-establishment
- Not suitable for bursty, small messages where setup cost dominates