Viewing TCP Group Information
10-2
Figure10-1. TCP Group Window
The left portion of the TCP Group window displays statistics about TCP circuits.
The right portion shows the current active connections.
TCP Statistics
Retransmit Algorithm
The algorithm used to determine the timeout value for retransmitting
unacknowledged octets, according to the tcpRtoAlgorithm.
• other (1)—none of the following
• constant (2)—a constant rto
• rsre (3)—MIL-STD-1778, Appendix B
• vanj—Van Jacobson’s algorithm
Every time TCP sends a segment, it starts a timer and waits for an
acknowledgement that the receiving station received the segment. If the timer
expires before the acknowledgment arrives, the sending station assumes that the
segment was lost or corrupted and retransmits the segment. To function in an
internet environment, TCP retransmission algorithms are adaptive, that is, each
segment received and acknowledged adds to TCP’s understanding of the time
required for a datagram to travel between the two nodes.
Rto. Min. (Retransmit time out Minimum)
The minimum value permitted by a TCP implementation for the retransmission
timeout (measured in milliseconds) according to the tcpRtoMin. More refined
semantics for objects of this type depend upon the algorithm used to determine
the retransmission timeout. In particular, when the timeout algorithm is rsre (3),
an object of this type has the semantics of the LBOUND quantity described in
RFC 793.