TCP_ESTATS_REC_ROD_v0 structure (tcpestats.h)
The TCP_ESTATS_REC_ROD_v0 structure contains read-only dynamic information for extended TCP statistics on the local receiver for a TCP connection.
Syntax
typedef struct _TCP_ESTATS_REC_ROD_v0 {
ULONG CurRwinSent;
ULONG MaxRwinSent;
ULONG MinRwinSent;
ULONG LimRwin;
ULONG DupAckEpisodes;
ULONG DupAcksOut;
ULONG CeRcvd;
ULONG EcnSent;
ULONG EcnNoncesRcvd;
ULONG CurReasmQueue;
ULONG MaxReasmQueue;
SIZE_T CurAppRQueue;
SIZE_T MaxAppRQueue;
UCHAR WinScaleSent;
} TCP_ESTATS_REC_ROD_v0, *PTCP_ESTATS_REC_ROD_v0;
Members
CurRwinSent
Type: ULONG
The most recent window advertisement, in bytes, that has been sent.
MaxRwinSent
Type: ULONG
The maximum window advertisement, in bytes, that has been sent.
MinRwinSent
Type: ULONG
The minimum window advertisement, in bytes, that has been sent.
LimRwin
Type: ULONG
The maximum window advertisement, in bytes, that may be sent.
DupAckEpisodes
Type: ULONG
The number of Duplicate Acks Sent when prior Ack was not duplicate. This is the number of times that a contiguous series of duplicate acknowledgments have been sent.
This is an indication of the number of data segments lost or reordered on the path from the remote TCP endpoint to the near TCP endpoint.
DupAcksOut
Type: ULONG
The number of duplicate ACKs sent.
The ratio of the change in the DupAcksOut member to the change in the DupAckEpisodes member is an indication of reorder or recovery distance over some interval.
CeRcvd
Type: ULONG
The number of segments received with IP headers bearing Congestion Experienced (CE) markings.
EcnSent
Type: ULONG
Reserved for future use. This member is always set to zero.
EcnNoncesRcvd
Type: ULONG
Reserved for future use. This member is always set to zero.
CurReasmQueue
Type: ULONG
The current number of bytes of sequence space spanned by the reassembly queue.
This is generally the difference between rcv.nxt and the sequence number of the right most edge of the reassembly queue.
MaxReasmQueue
Type: ULONG
The maximum number of bytes of sequence space spanned by the reassembly queue.
This is the maximum value of the CurReasmQueue member.
CurAppRQueue
Type: SIZE_T
The current number of bytes of application data that has been acknowledged by TCP but not yet delivered to the application.
MaxAppRQueue
Type: SIZE_T
The maximum number of bytes of application data that has been acknowledged by TCP but not yet delivered to the application.
WinScaleSent
Type: UCHAR
The value of the transmitted window scale option if one was sent; otherwise, a value of -1.
Note that if both the WinScaleSent member and the WinScaleRcvd member of the TCP_ESTATS_OBS_REC_ROD_v0 structure are not -1, then Rcv.Wind.Scale will be the same as this value and used to scale receiver window announcements from the local host to the remote host.
Remarks
The TCP_ESTATS_REC_ROD_v0 structure is used as part of the TCP extended statistics feature available on Windows Vista and later.
The TCP_ESTATS_REC_ROD_v0 is defined as version 0 of the structure for read-only dynamic information for extended TCP statistics on the local receiver for a TCP connection. This information is available after the connection has been established.
The TCP_ESTATS_REC_ROD_v0 structure is retrieved by calls to the GetPerTcp6ConnectionEStats or GetPerTcpConnectionEStats functions when TcpConnectionEstatsRec is passed in the EstatsType parameter. Extended TCP statistics need to be enabled to retrieve this structure.
TCP congestion control and congestion control algorithms are discussed in detail in the IETF RFC 2581 on TCP Congestion Control. For more information, see http://www.ietf.org/rfc/rfc2581.txt.
Explicit Congestion Notification in IP is discussed in detail in the IETF RFC 2581 on The Addition of Explicit Congestion Notification (ECN) to IP. For more information, see http://www.ietf.org/rfc/rfc3168.txt.
The members of this structure are defined in the IETF RFC on the TCP Extended Statistics MIB. For more information, see http://www.ietf.org/rfc/rfc4898.txt.
The following is the mapping of the members in the TCP_ESTATS_REC_ROD_v0 structure to the entries defined in RFC 4898 for extended TCP statistics:
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows Vista [desktop apps only] |
| Minimum supported server | Windows Server 2008 [desktop apps only] |
| Header | tcpestats.h |