1 files changed, 41 insertions, 0 deletions

diff --git a/Documentation/networking/dccp.txt b/Documentation/networking/dccp.txt
index a8142a81038a..c2328c862e98 100644
--- a/Documentation/networking/dccp.txt
+++ b/Documentation/networking/dccp.txt
@@ -63,6 +63,47 @@ DCCP_SOCKOPT_SEND_CSCOV is for the receiver and has a different meaning: it
         coverage value are also acceptable. The higher the number, the more
         restrictive this setting (see [RFC 4340, sec. 9.2.1]).
 
+Sysctl variables
+================
+Several DCCP default parameters can be managed by the following sysctls
+(sysctl net.dccp.default or /proc/sys/net/dccp/default):
+
+request_retries
+        The number of active connection initiation retries (the number of
+        Requests minus one) before timing out. In addition, it also governs
+        the behaviour of the other, passive side: this variable also sets
+        the number of times DCCP repeats sending a Response when the initial
+        handshake does not progress from RESPOND to OPEN (i.e. when no Ack
+        is received after the initial Request).  This value should be greater
+        than 0, suggested is less than 10. Analogue of tcp_syn_retries.
+
+retries1
+        How often a DCCP Response is retransmitted until the listening DCCP
+        side considers its connecting peer dead. Analogue of tcp_retries1.
+
+retries2
+        The number of times a general DCCP packet is retransmitted. This has
+        importance for retransmitted acknowledgments and feature negotiation,
+        data packets are never retransmitted. Analogue of tcp_retries2.
+
+send_ndp = 1
+        Whether or not to send NDP count options (sec. 7.7.2).
+
+send_ackvec = 1
+        Whether or not to send Ack Vector options (sec. 11.5).
+
+ack_ratio = 2
+        The default Ack Ratio (sec. 11.3) to use.
+
+tx_ccid = 2
+        Default CCID for the sender-receiver half-connection.
+
+rx_ccid = 2
+        Default CCID for the receiver-sender half-connection.
+
+seq_window = 100
+        The initial sequence window (sec. 7.5.2).
+
 Notes
 =====