Explicit Congestion Notification


If router finds that network is congested, router marks "ECN bit" in the IP header.
Data Receiver send back "ECN echo" after receiving ECN packets.
Data sender should set window size to minimum after receiving ECN echo.
Pros.
ECN is a bit slower than Source Quench.
Cons.
Can find congestion without packet loss.
Do not add any traffic in the networks.