doc: make the description of how tcp_ecn works more explicit and clear

Make the description of how tcp_ecn works a bit more explicit and clear.

Signed-off-by: Rick Jones <rick.jones2@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 8 deletions

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 98ac0d7552a1..c6d5fee888c4 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -199,15 +199,16 @@ tcp_early_retrans - INTEGER
         Default: 2
 
 tcp_ecn - INTEGER
-        Enable Explicit Congestion Notification (ECN) in TCP. ECN is only
-        used when both ends of the TCP flow support it. It is useful to
-        avoid losses due to congestion (when the bottleneck router supports
-        ECN).
+        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
-                1 ECN enabled
-                2 Only server-side ECN enabled. If the other end does
-                  not support ECN, behavior is like with ECN disabled.
+                0 Disable ECN.  Neither initiate nor accept ECN.
+                1 Always request ECN on outgoing connection attempts.
+                2 Enable ECN when requested by incomming connections
+                  but do not request ECN on outgoing connections.
         Default: 2
 
 tcp_fack - BOOLEAN