From: Youngseok Lee (yslee@cs.cnu.ac.kr)
Date: 06/21/04
From: "Youngseok Lee" <yslee@cs.cnu.ac.kr> Subject: tcptrace tcpdump sees packets but tcp do not receive them Date: Mon, 21 Jun 2004 14:22:06 +0900 Message-ID: <000301c4574f$bd74ae30$2a2cbca8@yourkgrvpgfonq>
Hi all,
After I've capture the tcp connection (iperf) at the receiver,
I've found an abnormal behavior of tcp at the host.
Could you have any idea about this problem ?
The problem is that the packet trace is seen by tcpdump,
but the tcp at the host does not react to the segments.
That is, the receiver does not send ACKs to the segments.
From the following trace, tcpdump was run at the machine with 5001
port.
Though its tcpdump sees the segment arrivals, it looks like frozen.
After timeout at the sender at the port 4260, it retransmitted the
packet,
then, the receiver begins to send ACK again.
This sympton always happen in my experiment regularly.
(sender is window2000 with cdma connection, receiver is linux 2.4
kernel.)
Is there anybody to comment to this ?
09:29:57.437996 211.246.16.2.4260 > 203.255.255.86.5001: .
40093:41553(1460) ack 1 win 17520 (DF)
09:29:57.491970 211.246.16.2.4260 > 203.255.255.86.5001: .
41553:43013(1460) ack 1 win 17520 (DF)
09:29:57.894954 211.246.16.2.4260 > 203.255.255.86.5001: .
43013:44473(1460) ack 1 win 17520 (DF)
09:29:57.916957 211.246.16.2.4260 > 203.255.255.86.5001: .
44473:45933(1460) ack 1 win 17520 (DF)
09:29:57.970434 211.246.16.2.4260 > 203.255.255.86.5001: P
45933:46825(892) ack 1 win 17520 (DF)
09:29:58.115005 211.246.16.2.4260 > 203.255.255.86.5001: .
46825:48285(1460) ack 1 win 17520 (DF)
09:29:58.131056 211.246.16.2.4260 > 203.255.255.86.5001: .
48285:49745(1460) ack 1 win 17520 (DF)
09:29:58.211018 211.246.16.2.4260 > 203.255.255.86.5001: .
49745:51205(1460) ack 1 win 17520 (DF)
09:29:58.290972 211.246.16.2.4260 > 203.255.255.86.5001: .
51205:52665(1460) ack 1 win 17520 (DF)
09:29:58.339522 211.246.16.2.4260 > 203.255.255.86.5001: P
52665:53557(892) ack 1 win 17520 (DF)
09:30:01.406100 211.246.16.2.4260 > 203.255.255.86.5001: P
40093:41553(1460) ack 1 win 17520 (DF)
09:30:01.505427 203.255.255.86.5001 > 211.246.16.2.4260: . ack 41553 win
65535
best regards,
Youngseok
=============================================================
Youngseok Lee
Department of Computer Science and Engineering
Faculty of Electrical and Computer Engineering
Chungnam National University
220 Gung-dong, Yuseong-gu, Daejeon 305-764, Korea
Tel : +82-42-821-6655, Fax: +82-42-822-4997
Cell: 016-497-4479
E-mail : yslee@cs.cnu.ac.kr
=============================================================
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