/iː-siː-iː/
n. “A TCP header flag used to indicate Explicit Congestion Notification.”
In the context of the Transmission Control Protocol (TCP), ECE (short for ECN Echo) is a flag that signals the detection of network congestion without dropping packets. It works in conjunction with Explicit Congestion Notification (ECN) mechanisms to provide more efficient and controlled congestion management.
When a TCP segment arrives with the ECE flag set, it informs the sender that the network has experienced congestion and that the sender should reduce its transmission rate to prevent further congestion.
Key characteristics of ECE include:
- Congestion Signaling: Alerts the sender to reduce the transmission rate due to congestion.
- Works with ECN: Part of the Explicit Congestion Notification mechanism.
- Efficient Network Management: Avoids packet loss by signaling congestion before queues overflow.
- Optional in TCP: Only used when both sender and receiver support ECN.
Conceptual example of ECE usage:
// TCP segment with ECE flag
Router detects congestion and marks packets with ECN
Receiver sets ECE flag in TCP header to notify sender
Sender slows down transmission rate
Transmission resumes without packet lossConceptually, ECE is like a gentle traffic signal for data: instead of crashing into congestion (packet loss), it politely warns the sender to slow down, maintaining smooth network flow.