When T3-rtx expires, the DATA chunks that triggered the T3
timer will be re-sent according with the retransmissions
rules. Every DATA chunk that was included in the SCTP packet
that triggered the T3-rtx timer must be added to the value of
this counter.
Discontinuities in the value of this counter can occur at re-
initialization of the management system, and at other times as
indicated by the value of sctpAssocDiscontinuityTime.