Turning on relative sequence numbers also allows Ethereal to detect and
understand TCP window scaling. Were scaling bits set in the SYN
segments for the connection? If so, I'm guessing that "747520" is the
CORRECT window size, and 5840 is the window size before shifting bits
(which is not the true size of the advertised window)...
Ian
On Jul 29, 2004, at 5:35 AM, Markus Rehbach wrote:
Hi all,
there seems to be a problem in 0.10.5 and probably older ones.
If preference is 'tcp.relative_sequence_numbers: TRUE' there is a wrong
value shown for the window size (3rd line below: Win=747520 should be
5840).
0.070763 a -> b TCP 32985 > imap [SYN] Seq=0 Ack=0 Win=5840 Len=0
MSS=1460 TSV=3609664 TSER=0 WS=7
0.071129 b -> a TCP imap > 32985 [SYN, ACK] Seq=0 Ack=1 Win=5840
Len=0 MSS=1460
0.071176 a -> b TCP 32985 > imap [ACK] Seq=1 Ack=1 Win=747520 Len=0
If preference is 'tcp.relative_sequence_numbers: FALSE' it looks good.
0.076386 a -> b TCP 32991 > imap [SYN] Seq=4090487846 Ack=0 Win=5840
Len=0 MSS=1460 TSV=4006974 TSER=0 WS=7
0.076748 b -> a TCP imap > 32991 [SYN, ACK] Seq=3661596958
Ack=4090487847 Win=5840 Len=0 MSS=1460
0.076798 a -> b TCP 32991 > imap [ACK] Seq=4090487847 Ack=3661596959
Win=5840 Len=0
Problem shows up in ethereal and tethereal (no surprise;-).
Markus
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