Control use of Explicit Congestion Notification (ECN) by TCP. ECN is used only when both ends of the TCP connection indicate support for it. This feature is useful in avoiding losses due to congestion by allowing supporting routers to signal congestion before having to drop packets. Possible values are: 0 Disable ECN. Neither initiate nor accept ECN. 1 Enable ECN when requested by incoming connections and also request ECN on outgoing connection attempts. 2 Enable ECN when requested by incoming connections but do not request ECN on outgoing connections. Default: 2
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