TcpRun loses exactly one frame (loseFirst: the card's output buffer drops
it; the sender's packet log still shows it, as with setDrop) in three new
stories: lostSynAck, lostFin, lostLastFin.
Measured: Java never repeats a SYN+ACK or a FIN. The server gives a
handshake up after one timeout (3 RTT) and closes with a FIN from SYN_RCVD
(its boundary check sometimes lets it wait twice; it means once). After its
FIN a socket waits at most five times, each wait ended by a segment or the
timeout; then it is gone. The core does the same (TCP_CLOSING_WAITS, with
TIME_WAIT in the loop) and shows CLOSED where Java leaves the state
standing (a named Java bug).
One departure: a repeated SYN in SYN_RCVD gets the SYN+ACK once more and
the wait starts anew; Java closes there, but its client never repeats the
SYN. lostSynAck is compared up to the second SYN (JAVA_UNTIL); the rest is
an engine test.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Java's SimplexVerbindung sleeps a cable's delay with the port's buffer
locked: frames on one cable leave one after the other, and a frame shows
in the packet log when it leaves. The engine now queues a frame in the
output buffer until the one before has arrived (ethernetLinkDeparture).
Swift sends a cable's frames at once; the option swiftCables keeps that for
the Swift comparison, which goes on checking everything else trace by
trace.
With the queue, the Java comparisons match within 120 ms (was 200); a
state of the TCP stories within 250 ms, where the engine's calls block
one after the other.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
TCP follows Java's TCPSocket where it differs from Swift: each attempt and
TIME_WAIT wait three round trips that follow the speed (8250 ms at 90 %),
counted from when the segment is handed down, before ARP; the next segment
ends TIME_WAIT; the other end closes by itself on FIN; data no one
acknowledges closes with FIN; the accepted socket has the listener's
initial sequence number, and the listener takes the next.
Not taken from Java: three SYNs, not one (Java's retry loop ends after
the first timeout), named in tcpJava.test.ts as JAVA_BUGS.
tcpJava.test.ts compares TcpRun's three stories frame by frame and state
by state; the Swift comparison only checks that the TCP scenarios differ.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
julian.kiedaischandClaude Opus 5.5