[Ns-bugs] [Bug 166] Loss of Tag and change in size of Packet using TCP.

[bugzilla-daemon@nsnam-www.ece.gatech.edu]

http://www.nsnam.org/bugzilla/show_bug.cgi?id=166


liujatp at gmail.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |raj.b at gatech.edu,
                   |                            |liujatp at gmail.com




------- Comment #2 from liujatp at gmail.com  2008-04-15 03:18 -------

(In reply to comment #0)
> I have a Packet that I send using a point-to-point TCP connection. I am seeing
> an attached Tag disappear on the receiving side and the size changes. I think
> these both may be bugs. I'll attach a test case below. 
> I've used the component of internet-node, but thats just a wild guess.
> Compile---%<-------------------%<----------%<----------%<----------%<---------%<
> g++ -DNS3_ASSERT_ENABLE -DNS3_LOG_ENABLE -DDEBUG -g -O0
> -I/.../ns-3-dev/build/debug -I/.../ns-3-dev/build/debug -I.
> -L/home/evensky/ns-3-dev/build/debug -lns3 -Wl,-rpath=/.../ns-3-dev/build/debug
>  -o tcp-tester tcp-tester.cc
> Output---%<-------------------%<----------%<----------%<----------%<---------%<
> evensky at waltz:~/tools/trunk$ ./tcp-tester 
> TalkerApp::ConfRecv(0x62e360,00:00:00:00:20:00) Server
> TalkerApp::ConfSend(0x62d9a0,0a:01:00:02:20:00) Client
> TalkerApp::StartApplication() Server
> TalkerApp::StartApplicationRecv() Server
> TalkerApp::StartApplication() Client
> TalkerApp::StartApplicationSend() Client
> writing packet Client
>    Payload (size=536)(tag=17)
> TalkerApp::CloseConnection(): Client
> TalkerApp::ConnectionRequested(): Server
> TalkerApp::ConnectionSucceeded(): Client
> TalkerApp::ConnectionCreated(): Server
> Received 535 bytes from 10.1.0.1 [0a:01:00:01:01:c0]---''
>    Payload (size=535)
> TalkerApp::ConnectionCloseRequested(): Server
> TalkerApp::CloseConnection(): Server
> note, that the size changes from 536->535 and the tag is gone.

1, "536->535" caused in TcpSocket::SendPendingData ()::
Ptr<Packet> p = m_pendingData->CopyFromSeq (s, m_firstPendingSequence, 
        m_nextTxSequence);
when m_firstPendingSequence = 0, m_nextTxSequence = 1; the packet size decrease
by 1. Actually i have no idea about how it works like that, maybe you should
contact Raj Bhattacharjea <raj.b at gatech.edu> for more.

2,the tag is gone:: you cannot add packet header in application layer. TCP
socket just send data by ptr,
TcpSocket::Send (const Ptr<Packet> p) //p here is just data, no headers
Application header shoud be added in application data ptr. 

wish it can help you.

Liu,

> Thanks,
> \dae


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