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Subject: cipe win-linux
From: Thomas Schaefer <mail,AT,thomas--schaefer,DOT,de>
Date: Wed, 24 Jul 2002 21:12:05 +0200

Hi,

Firstly my configuration:

An application on a PC with winNT, also one end of cipe (nt-version by DKW)
some network between ...
a PC with linux (Suse7.3) second end of cipe and as router,
a host with different services for management (SNMP, tftp, telnet ...)
Mostly everything is ok.
But today I had a reproducable failure:
I made a tftp-upload from the windows-PC via the tunnel to the host.
The transfer was interrupted at the same place in any attempt.( ca.4MB alreay 
transfered)
Direct transfers (without cipe) worked.

..
    905 9.956763    192.1.12.180          10.0.12.1             TFTP     
Acknowledgement, Block: 8204
    906 9.969972    10.0.12.1             192.1.12.180          TFTP     Data 
Packet, Block: 8205
    907 9.977277    192.1.12.180          10.0.12.1             TFTP     
Acknowledgement, Block: 8205
    908 9.989398    10.0.12.1             192.1.12.180          TFTP     Data 
Packet, Block: 8206
    909 9.995402    192.1.12.180          10.0.12.1             TFTP     
Acknowledgement, Block: 8206
    910 10.007506   10.0.12.1             192.1.12.180          TFTP     Data 
Packet, Block: 8207
    911 10.013522   192.1.12.180          10.0.12.1             TFTP     
Acknowledgement, Block: 8207
    912 13.028191   10.0.12.1             192.1.12.180          TFTP     Data 
Packet, Block: 8207
    913 13.034175   192.1.12.180          10.0.12.1             TFTP     
Acknowledgement, Block: 8207
    914 18.033731   10.0.12.1             192.1.12.180          TFTP     Data 
Packet, Block: 8207
    915 18.039690   192.1.12.180          10.0.12.1             TFTP     
Acknowledgement, Block: 8207
    916 26.038213   10.0.12.1             192.1.12.180          TFTP     Data 
Packet, Block: 8207
    917 26.039281   10.0.12.1             192.1.12.180          TFTP     
Error Code, Code: Not defined, Message: timing out
    918 26.150407   192.1.12.180          10.0.12.1             TFTP     
Acknowledgement, Block: 8207
...

This trace was made on the cipe-interface on the linux box. 
The acknowledgment seems never to reach the application on the PC.(10.12.0.1)
Therefore the application repeats with data-packets.

The suspect acknowledgement-packet in detail:
(first on cipe-interface on linux, second on eth-interface on winnt)
The records are unfortanetely not exact the same. (not traced at once)
But the effect was the same - the application(tftp) misses the 
acknowledgement and repeats with data.

Frame 915 (32 on wire, 32 captured)
    Arrival Time: Jul 24, 2002 16:32:39.364019000
    Time delta from previous packet: 0.005959000 seconds
    Time relative to first packet: 18.039690000 seconds
    Frame Number: 915
    Packet Length: 32 bytes
    Capture Length: 32 bytes
Raw packet data
    No link information available
Internet Protocol, Src Addr: 192.1.12.180 (192.1.12.180), Dst Addr: 10.0.12.1 
(10.0.12.1)
    Version: 4
    Header length: 20 bytes
    Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
        0000 00.. = Differentiated Services Codepoint: Default (0x00)
        .... ..0. = ECN-Capable Transport (ECT): 0
        .... ...0 = ECN-CE: 0
    Total Length: 32
    Identification: 0xa726
    Flags: 0x00
        .0.. = Don't fragment: Not set
        ..0. = More fragments: Not set
    Fragment offset: 0
    Time to live: 29
    Protocol: UDP (0x11)
    Header checksum: 0x13f1 (correct)
    Source: 192.1.12.180 (192.1.12.180)
    Destination: 10.0.12.1 (10.0.12.1)
User Datagram Protocol, Src Port: 69 (69), Dst Port: 4802 (4802)
    Source port: 69 (69)
    Destination port: 4802 (4802)
    Length: 12
    Checksum: 0x0000 (none)
Trivial File Transfer Protocol
    Opcode: Acknowledgement (4)
    Block: 8207

0000  45 00 00 20 a7 26 00 00 1d 11 13 f1 c0 01 0c b4   E.. .&..........
0010  0a 00 0c 01 00 45 12 c2 00 0c 00 00 00 04 20 0f   .....E........ .

Frame 2275 (74 on wire, 74 captured)
    Arrival Time: Jul 24, 2002 16:23:58.098633000
    Time delta from previous packet: 0.011147000 seconds
    Time relative to first packet: 11.302786000 seconds
    Frame Number: 2275
    Packet Length: 74 bytes
    Capture Length: 74 bytes
Ethernet II
    Destination: 00:e0:00:17:3a:fc (00:e0:00:17:3a:fc)
    Source: 00:30:f2:0f:90:00 (00:30:f2:0f:90:00)
    Type: IP (0x0800)
Internet Protocol, Src Addr: 139.21.185.109 (139.21.185.109), Dst Addr: 
139.21.89.61 (139.21.89.61)
    Version: 4
    Header length: 20 bytes
    Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
        0000 00.. = Differentiated Services Codepoint: Default (0x00)
        .... ..0. = ECN-Capable Transport (ECT): 0
        .... ...0 = ECN-CE: 0
    Total Length: 60
    Identification: 0x6835
    Flags: 0x00
        .0.. = Don't fragment: Not set
        ..0. = More fragments: Not set
    Fragment offset: 0
    Time to live: 27
    Protocol: UDP (0x11)
    Header checksum: 0x0ea7 (correct)
    Source: 139.21.185.109 (139.21.185.109)
    Destination: 139.21.89.61 (139.21.89.61)
User Datagram Protocol, Src Port: 9012 (9012), Dst Port: 9012 (9012)
    Source port: 9012 (9012)
    Destination port: 9012 (9012)
    Length: 40
    Checksum: 0x0000 (none)
Data (32 bytes)

0000  00 e0 00 17 3a fc 00 30 f2 0f 90 00 08 00 45 00   ....:..0......E.
0010  00 3c 68 35 00 00 1b 11 0e a7 8b 15 b9 6d 8b 15   .<h5.........m..
0020  59 3d 23 34 23 34 00 28 00 00 45 00 00 20 a7 24   Y=#4#4.(..E.. .$
0030  00 00 1d 11 13 f3 c0 01 0c b4 0a 00 0c 01 00 45   ...............E
0040  12 c2 00 0c 00 00 00 04 20 0f                     ........ .

Please, don't hate me. I am not sure if it is the "short packet problem".
May be someone finds the reason, why the packet does not reache the 
application.

Regards,
Thomas Schäfer

-- 
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