// SUT initiates connection. SUT sends data. Sacks are injected with gaps.
// A retransmission is triggered.
+0       socket(..., SOCK_STREAM, IPPROTO_SCTP) = 3
+0       connect(3, ..., ...) = -1 EINPROGRESS (Operation now in progress)
+0     > sctp: INIT[flgs=0, tag=..., a_rwnd=..., os=2048, is=10, tsn=0, ...]
+0.05  < sctp: INIT_ACK[flgs=0, tag=22, a_rwnd=100000, os=2048, is=10, tsn=0, STATE_COOKIE[len=4, val=...]]
+0     > sctp: COOKIE_ECHO[flgs=0, len=4, val=...]
+0.05     < sctp: COOKIE_ACK[flgs=0]
+0.20    write(3, ..., 1000) = 1000
+0     > sctp: DATA[flgs=BE, len=1016, tsn=0, sid=0, ssn=0, ppid=0] // Other flags allowed: IU
+0.10  < sctp: SACK[flgs=0, cum_tsn=0, a_rwnd=100000, gaps=[], dups=[]]
+0.05    write(3, ..., 1000) = 1000
+0     > sctp: DATA[flgs=BE, len=1016, tsn=1, sid=1, ssn=0, ppid=0]
+0       write(3, ..., 1000) = 1000
+0     > sctp: DATA[flgs=BE, len=1016, tsn=2, sid=2, ssn=0, ppid=0]
+0.10  < sctp: SACK[flgs=0, cum_tsn=0, a_rwnd=100000, gaps=[2 : 2], dups=[]]
+0       write(3, ..., 1000) = 1000
+0     > sctp: DATA[flgs=BE, len=1016, tsn=3, sid=3, ssn=0, ppid=0]
+0.10  < sctp: SACK[flgs=0, cum_tsn=0, a_rwnd=100000, gaps=[2 : 3], dups=[]]
+0       write(3, ..., 1000) = 1000
+0     > sctp: DATA[flgs=BE, len=1016, tsn=4, sid=4, ssn=0, ppid=0]
+0.10  < sctp: SACK[flgs=0, cum_tsn=0, a_rwnd=100000, gaps=[2 : 4], dups=[2 : 2]]
+0     > sctp: DATA[flgs=BE, len=1016, tsn=1, sid=1, ssn=0, ppid=0]
+0.10  < sctp: SACK[flgs=0, cum_tsn=4, a_rwnd=100000, gaps=[], dups=[]]
+0.20    close(3) = 0
+0     > sctp: SHUTDOWN[flgs=0, cum_tsn=...]
+0.05  < sctp: SHUTDOWN_ACK[flgs=0]
+0     > sctp: SHUTDOWN_COMPLETE[flgs=0] // Other flags allowed: T, Is SHUTDOWN_COMPLETE[] allowed?