1 files changed, 70 insertions, 18 deletions

diff --git a/Documentation/networking/dccp.txt b/Documentation/networking/dccp.txt
index 74563b38ffd9..387482e46c47 100644
--- a/Documentation/networking/dccp.txt
+++ b/Documentation/networking/dccp.txt
@@ -19,40 +19,92 @@ for real time and multimedia traffic.
 
 It has a base protocol and pluggable congestion control IDs (CCIDs).
 
-It is at draft RFC status and the homepage for DCCP as a protocol is at:
-        http://www.icir.org/kohler/dcp/
+It is at proposed standard RFC status and the homepage for DCCP as a protocol
+is at:
+        http://www.read.cs.ucla.edu/dccp/
 
 Missing features
 ================
 
 The DCCP implementation does not currently have all the features that are in
-the draft RFC.
+the RFC.
 
-In particular the following are missing:
-- CCID2 support
-- feature negotiation
-
-When testing against other implementations it appears that elapsed time
-options are not coded compliant to the specification.
+The known bugs are at:
+        http://linux-net.osdl.org/index.php/TODO#DCCP
 
 Socket options
 ==============
 
-DCCP_SOCKOPT_PACKET_SIZE is used for CCID3 to set default packet size for
-calculations.
-
 DCCP_SOCKOPT_SERVICE sets the service. The specification mandates use of
 service codes (RFC 4340, sec. 8.1.2); if this socket option is not set,
 the socket will fall back to 0 (which means that no meaningful service code
 is present). Connecting sockets set at most one service option; for
 listening sockets, multiple service codes can be specified.
 
+DCCP_SOCKOPT_SEND_CSCOV and DCCP_SOCKOPT_RECV_CSCOV are used for setting the
+partial checksum coverage (RFC 4340, sec. 9.2). The default is that checksums
+always cover the entire packet and that only fully covered application data is
+accepted by the receiver. Hence, when using this feature on the sender, it must
+be enabled at the receiver, too with suitable choice of CsCov.
+
+DCCP_SOCKOPT_SEND_CSCOV sets the sender checksum coverage. Values in the
+        range 0..15 are acceptable. The default setting is 0 (full coverage),
+        values between 1..15 indicate partial coverage.
+DCCP_SOCKOPT_SEND_CSCOV is for the receiver and has a different meaning: it
+        sets a threshold, where again values 0..15 are acceptable. The default
+        of 0 means that all packets with a partial coverage will be discarded.
+        Values in the range 1..15 indicate that packets with minimally such a
+        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).
+
+tx_qlen = 5
+        The size of the transmit buffer in packets. A value of 0 corresponds
+        to an unbounded transmit buffer.
+
 Notes
 =====
 
-SELinux does not yet have support for DCCP. You will need to turn it off or
-else you will get EACCES.
-
-DCCP does not travel through NAT successfully at present. This is because
-the checksum covers the psuedo-header as per TCP and UDP. It should be
-relatively trivial to add Linux NAT support for DCCP.
+DCCP does not travel through NAT successfully at present on many boxes. This is
+because the checksum covers the psuedo-header as per TCP and UDP. Linux NAT
+support for DCCP has been added.