ECn

ECN is an acronym that can refer to several technologies depending on the context, most commonly in finance and in computer networking.

In finance, Electronic Communications Network refers to an electronic trading system that matches buy and sell orders for securities outside traditional stock exchanges. ECNs provide direct access to liquidity pools, enabling faster execution, time-stamped trades, and often greater pre-trade transparency. They can operate as alternative trading systems and may support after-hours trading. ECNs contributed to increased competition among liquidity providers, tighter bid-ask spreads, and improved price discovery. They are subject to financial regulation and require market participants to maintain connectivity and compliance with trading rules.

In computer networking, Explicit Congestion Notification is a mechanism that signals network congestion without dropping packets. ECN uses specific bits in IP and TCP headers to indicate congestion and to mark packets when routers experience queuing delays. Endpoints that support ECN adjust their transmission rates in response to the congestion signal, potentially improving throughput and reducing retransmissions. ECN works best when both communicating endpoints and the network infrastructure support it and is defined in standards such as RFC 3168. It is commonly used alongside congestion control algorithms and can interact with active queue management techniques.

Aside from these primary meanings, ECN can denote other domain-specific concepts, but the two above are the most widely encountered. The term is typically clarified by context to avoid ambiguity.