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Message-ID: <CAMRd1sV_ZzgFF8a2D=CsugHPHrNY=ifV1F46bKVwNSP9FvNPUw@mail.gmail.com>
Date: Mon, 14 Apr 2014 13:02:16 +0800
From: chptx y <chptxy@...il.com>
To: Eric Dumazet <eric.dumazet@...il.com>
Cc: Sharat Masetty <sharat04@...il.com>,
Linux Netdev List <netdev@...r.kernel.org>
Subject: Re: What causes these TCP packet getting lost in linux kernel
Text exporting from wireshark, is it OK?
---------------------------------------------------------------------------------------------------------
Frame 30: 168 bytes on wire (1344 bits), 168 bytes captured (1344 bits)
Transmission Control Protocol, Src Port: http (80), Dst Port: 34865
(34865), Seq: 12517, Ack: 3086, Len: 100
Source port: http (80)
Destination port: 34865 (34865)
[Stream index: 0]
Sequence number: 12517 (relative sequence number)
[Next sequence number: 12617 (relative sequence number)]
Acknowledgement number: 3086 (relative ack number)
Header length: 32 bytes
Flags: 0x010 (ACK)
Window size value: 7541
[Calculated window size: 7541]
[Window size scaling factor: 1]
Checksum: 0x89d8 [correct]
[Good Checksum: True]
[Bad Checksum: False]
Options: (12 bytes)
[SEQ/ACK analysis]
[Reassembled PDU in frame: 34]
TCP segment data (100 bytes)
Frame 31: 68 bytes on wire (544 bits), 68 bytes captured (544 bits)
Transmission Control Protocol, Src Port: 34865 (34865), Dst Port: http
(80), Seq: 3086, Ack: 12617, Len: 0
Source port: 34865 (34865)
Destination port: http (80)
[Stream index: 0]
Sequence number: 3086 (relative sequence number)
Acknowledgement number: 12617 (relative ack number)
Header length: 32 bytes
Flags: 0x010 (ACK)
Window size value: 5001
[Calculated window size: 40008]
[Window size scaling factor: 8]
Checksum: 0x8213 [incorrect, should be 0x1614 (maybe caused by
"TCP checksum offload"?)]
[Good Checksum: False]
[Bad Checksum: True]
Options: (12 bytes)
[SEQ/ACK analysis]
Frame 32: 1416 bytes on wire (11328 bits), 1416 bytes captured (11328 bits)
Transmission Control Protocol, Src Port: http (80), Dst Port: 34865
(34865), Seq: 12617, Ack: 3086, Len: 1348
Source port: http (80)
Destination port: 34865 (34865)
[Stream index: 0]
Sequence number: 12617 (relative sequence number)
[Next sequence number: 13965 (relative sequence number)]
Acknowledgement number: 3086 (relative ack number)
Header length: 32 bytes
Flags: 0x010 (ACK)
Window size value: 7541
[Calculated window size: 7541]
[Window size scaling factor: 1]
Checksum: 0x4139 [correct]
[Good Checksum: True]
[Bad Checksum: False]
Options: (12 bytes)
[SEQ/ACK analysis]
[Reassembled PDU in frame: 34]
TCP segment data (1348 bytes)
Frame 33: 68 bytes on wire (544 bits), 68 bytes captured (544 bits)
Transmission Control Protocol, Src Port: 34865 (34865), Dst Port: http
(80), Seq: 3086, Ack: 12617, Len: 0
Source port: 34865 (34865)
Destination port: http (80)
[Stream index: 0]
Sequence number: 3086 (relative sequence number)
Acknowledgement number: 12617 (relative ack number)
Header length: 32 bytes
Flags: 0x010 (ACK)
Window size value: 5001
[Calculated window size: 40008]
[Window size scaling factor: 8]
Checksum: 0x8213 [incorrect, should be 0x1614 (maybe caused by
"TCP checksum offload"?)]
[Good Checksum: False]
[Bad Checksum: True]
Options: (12 bytes)
[SEQ/ACK analysis]
Frame 34: 687 bytes on wire (5496 bits), 687 bytes captured (5496 bits)
Transmission Control Protocol, Src Port: http (80), Dst Port: 34865
(34865), Seq: 13965, Ack: 3086, Len: 619
Source port: http (80)
Destination port: 34865 (34865)
[Stream index: 0]
Sequence number: 13965 (relative sequence number)
[Next sequence number: 14584 (relative sequence number)]
Acknowledgement number: 3086 (relative ack number)
Header length: 32 bytes
Flags: 0x018 (PSH, ACK)
Window size value: 7541
[Calculated window size: 7541]
[Window size scaling factor: 1]
Checksum: 0xf362 [correct]
[Good Checksum: True]
[Bad Checksum: False]
Options: (12 bytes)
[SEQ/ACK analysis]
TCP segment data (619 bytes)
[7 Reassembled TCP Segments (3415 bytes): #28(1348), #30(100),
#32(1348), #38(1348), #40(1348), #34(619), #36(619)]
Hypertext Transfer Protocol
Line-based text data: text/plain
Frame 35: 68 bytes on wire (544 bits), 68 bytes captured (544 bits)
Transmission Control Protocol, Src Port: 34865 (34865), Dst Port: http
(80), Seq: 3086, Ack: 12617, Len: 0
Source port: 34865 (34865)
Destination port: http (80)
[Stream index: 0]
Sequence number: 3086 (relative sequence number)
Acknowledgement number: 12617 (relative ack number)
Header length: 32 bytes
Flags: 0x010 (ACK)
Window size value: 5001
[Calculated window size: 40008]
[Window size scaling factor: 8]
Checksum: 0x8213 [incorrect, should be 0x1614 (maybe caused by
"TCP checksum offload"?)]
[Good Checksum: False]
[Bad Checksum: True]
Options: (12 bytes)
[SEQ/ACK analysis]
Frame 36: 687 bytes on wire (5496 bits), 687 bytes captured (5496 bits)
Transmission Control Protocol, Src Port: http (80), Dst Port: 34865
(34865), Seq: 13965, Ack: 3086, Len: 619
Source port: http (80)
Destination port: 34865 (34865)
[Stream index: 0]
Sequence number: 13965 (relative sequence number)
[Next sequence number: 14584 (relative sequence number)]
Acknowledgement number: 3086 (relative ack number)
Header length: 32 bytes
Flags: 0x018 (PSH, ACK)
Window size value: 7541
[Calculated window size: 7541]
[Window size scaling factor: 1]
Checksum: 0xeb4e [correct]
[Good Checksum: True]
[Bad Checksum: False]
Options: (12 bytes)
[SEQ/ACK analysis]
[Reassembled PDU in frame: 34]
TCP segment data (619 bytes)
Frame 37: 80 bytes on wire (640 bits), 80 bytes captured (640 bits)
Transmission Control Protocol, Src Port: 34865 (34865), Dst Port: http
(80), Seq: 3086, Ack: 12617, Len: 0
Source port: 34865 (34865)
Destination port: http (80)
[Stream index: 0]
Sequence number: 3086 (relative sequence number)
Acknowledgement number: 12617 (relative ack number)
Header length: 44 bytes
Flags: 0x010 (ACK)
Window size value: 5001
[Calculated window size: 40008]
[Window size scaling factor: 8]
Checksum: 0x821f [incorrect, should be 0xec6d (maybe caused by
"TCP checksum offload"?)]
[Good Checksum: False]
[Bad Checksum: True]
Options: (24 bytes)
[SEQ/ACK analysis]
Frame 38: 1416 bytes on wire (11328 bits), 1416 bytes captured (11328 bits)
Transmission Control Protocol, Src Port: http (80), Dst Port: 34865
(34865), Seq: 12617, Ack: 3086, Len: 1348
Source port: http (80)
Destination port: 34865 (34865)
[Stream index: 0]
Sequence number: 12617 (relative sequence number)
[Next sequence number: 13965 (relative sequence number)]
Acknowledgement number: 3086 (relative ack number)
Header length: 32 bytes
Flags: 0x010 (ACK)
Window size value: 7541
[Calculated window size: 7541]
[Window size scaling factor: 1]
Checksum: 0x3925 [correct]
[Good Checksum: True]
[Bad Checksum: False]
Options: (12 bytes)
[SEQ/ACK analysis]
[Reassembled PDU in frame: 34]
TCP segment data (1348 bytes)
Frame 39: 68 bytes on wire (544 bits), 68 bytes captured (544 bits)
Transmission Control Protocol, Src Port: 34865 (34865), Dst Port: http
(80), Seq: 3086, Ack: 14584, Len: 0
Source port: 34865 (34865)
Destination port: http (80)
[Stream index: 0]
Sequence number: 3086 (relative sequence number)
Acknowledgement number: 14584 (relative ack number)
Header length: 32 bytes
Flags: 0x010 (ACK)
Window size value: 5246
[Calculated window size: 41968]
[Window size scaling factor: 8]
Checksum: 0x8213 [incorrect, should be 0x0ba3 (maybe caused by
"TCP checksum offload"?)]
[Good Checksum: False]
[Bad Checksum: True]
Options: (12 bytes)
[SEQ/ACK analysis]
Frame 40: 1416 bytes on wire (11328 bits), 1416 bytes captured (11328 bits)
Transmission Control Protocol, Src Port: http (80), Dst Port: 34865
(34865), Seq: 12617, Ack: 3086, Len: 1348
Source port: http (80)
Destination port: 34865 (34865)
[Stream index: 0]
Sequence number: 12617 (relative sequence number)
[Next sequence number: 13965 (relative sequence number)]
Acknowledgement number: 3086 (relative ack number)
Header length: 32 bytes
Flags: 0x010 (ACK)
Window size value: 7541
[Calculated window size: 7541]
[Window size scaling factor: 1]
Checksum: 0x3844 [correct]
[Good Checksum: True]
[Bad Checksum: False]
Options: (12 bytes)
[SEQ/ACK analysis]
[Reassembled PDU in frame: 34]
TCP segment data (1348 bytes)
Frame 41: 80 bytes on wire (640 bits), 80 bytes captured (640 bits)
Transmission Control Protocol, Src Port: 34865 (34865), Dst Port: http
(80), Seq: 3086, Ack: 14584, Len: 0
Source port: 34865 (34865)
Destination port: http (80)
[Stream index: 0]
Sequence number: 3086 (relative sequence number)
Acknowledgement number: 14584 (relative ack number)
Header length: 44 bytes
Flags: 0x010 (ACK)
Window size value: 5293
[Calculated window size: 42344]
[Window size scaling factor: 8]
Checksum: 0x821f [incorrect, should be 0xe985 (maybe caused by
"TCP checksum offload"?)]
[Good Checksum: False]
[Bad Checksum: True]
Options: (24 bytes)
[SEQ/ACK analysis]
Frame 42: 68 bytes on wire (544 bits), 68 bytes captured (544 bits)
Transmission Control Protocol, Src Port: 34865 (34865), Dst Port: http
(80), Seq: 3086, Ack: 14584, Len: 0
Source port: 34865 (34865)
Destination port: http (80)
[Stream index: 0]
Sequence number: 3086 (relative sequence number)
Acknowledgement number: 14584 (relative ack number)
Header length: 32 bytes
Flags: 0x011 (FIN, ACK)
Window size value: 5293
[Calculated window size: 42344]
[Window size scaling factor: 8]
Checksum: 0x8213 [incorrect, should be 0x09a7 (maybe caused by
"TCP checksum offload"?)]
[Good Checksum: False]
[Bad Checksum: True]
Options: (12 bytes)
2014-04-13 3:32 GMT+08:00 Eric Dumazet <eric.dumazet@...il.com>:
> On Sat, 2014-04-12 at 12:35 -0600, Sharat Masetty wrote:
>> Check /proc/net/netstat and /proc/net/snmp
>>
>> In netstat look for
>>
>> LINUX_MIB_TCPOFODROP and LINUX_MIB_BACKLOGDROP
>
> The packet is not out of order, according to tcpdump.
>
> Note that the receiver reacts to incoming packet, sending a DUPACK, so
> its not a backlogdrop.
>
> tcpdump trace is really incomplete, I asked tcpdump -vv but got nothing
> from chptx, assuming this is a real name.
>
> packet might be rejected because of a zero receiver window, who knows.
>
> I might search in my basement this crystal ball I might have.
>
>
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