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TCP_INITIAL_RTO_PARAMETERS structure (mstcpip.h)

  • Article

Specifies data used by the SIO_TCP_INITIAL_RTO IOCTL to configure initial retransmission timeout (RTO) parameters to be used on the socket. The Windows TCP/IP stack will honor the values in this struct's members for subsequent connection attempts.

Syntax

typedef struct _TCP_INITIAL_RTO_PARAMETERS {
  USHORT Rtt;
  UCHAR  MaxSynRetransmissions;
} TCP_INITIAL_RTO_PARAMETERS, *PTCP_INITIAL_RTO_PARAMETERS;

Members

Rtt

Supplies the initial round trip time (RTT) estimate in milliseconds. This value is used to compute the retransmission timeout.

MaxSynRetransmissions

Supplies the maximum number of retransmissions that will be attempted before the connection setup fails. The retransmission behavior for TCP is documented in IETF RFC 793 and 2988.

  • Use one of the unspecified defines TCP_INITIAL_RTO_UNSPECIFIED_RTT and TCP_INITIAL_RTO_UNSPECIFIED_MAX_SYN_RETRANSMISSIONS to allow the system to pick up administrator-configured settings for the parameter left unspecified.
  • You can choose system defaults for any of these fields, and supply those values using the default defines TCP_INITIAL_RTO_DEFAULT_RTT and TCP_INITIAL_RTO_DEFAULT_MAX_SYN_RETRANSMISSIONS.
  • You can use the define TCP_INITIAL_RTO_NO_SYN_RETRANSMISSIONS to set the number of SYN retransmissions for a TCP socket to 0 (in other words, the TCP SYN shouldn't be retransmitted).

Requirements

Requirement Value
Minimum supported client Windows 8 [desktop apps only]
Minimum supported server Windows Server 2012 [desktop apps only]
Header mstcpip.h

See also

SIO_TCP_INITIAL_RTO