Only TCP segments that contains data have to be reordered ? - TCP-IP

This is a discussion on Only TCP segments that contains data have to be reordered ? - TCP-IP ; Hi, I think this question might be a simple one, but I did not find the RFC 793 clear in the matter: regarding out of order TCP segments, only those segments that contain data have to be reordered or others ...

+ Reply to Thread
Results 1 to 4 of 4

Thread: Only TCP segments that contains data have to be reordered ?

  1. Only TCP segments that contains data have to be reordered ?

    Hi,

    I think this question might be a simple one, but I did not find the RFC
    793
    clear in the matter: regarding out of order TCP segments, only those
    segments
    that contain data have to be reordered or others like FIN segments also
    have to be ordered ?

    RFC 793 generally puts the word data in the sentences where reorder
    is in it like:

    "
    The TCP must recover from data that is damaged, lost, duplicated, or
    delivered out of order by the internet communication system
    "

    or

    " A stream of data sent on a TCP connection is delivered reliably and
    in
    order at the destination.
    "

    But in this other place it looks like all segments have to be
    reordered:

    "
    A natural way to think about processing incoming segments is to
    imagine that they are first tested for proper sequence number (i.e.,
    that their contents lie in the range of the expected "receive window"
    in the sequence number space) and then that they are generally queued
    and processed in sequence number order.
    "

    Thanks


  2. Re: Only TCP segments that contains data have to be reordered ?

    joseluismarchetti@yahoo.com.br wrote:
    > I think this question might be a simple one, but I did not find the
    > RFC 793 clear in the matter: regarding out of order TCP segments,
    > only those segments that contain data have to be reordered or others
    > like FIN segments also have to be ordered ?


    The receiving application cannot be notified of the arrival of the FIN
    until after it has been notified of the arrival of preceeding
    data. (Similarly the FIN cannot be ACKed until all preceeding data has
    arrived). That is to say, that everything in the TCP sequence space
    is dealt with in order.

    rick jones
    --
    Wisdom Teeth are impacted, people are affected by the effects of events.
    these opinions are mine, all mine; HP might not want them anyway...
    feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

  3. Re: Only TCP segments that contains data have to be reordered ?

    In article <1148687418.332913.258550@g10g2000cwb.googlegroups. com>,
    joseluismarchetti@yahoo.com.br wrote:

    > Hi,
    >
    > I think this question might be a simple one, but I did not find the RFC
    > 793
    > clear in the matter: regarding out of order TCP segments, only those
    > segments
    > that contain data have to be reordered or others like FIN segments also
    > have to be ordered ?


    SYN and FIN segments take up a byte of sequence number space, precisely
    so that they can be fit into the proper order.

    And if you process a FIN out of order, you'll end up missing the last
    few data segments, which would clearly be wrong.

    --
    Barry Margolin, barmar@alum.mit.edu
    Arlington, MA
    *** PLEASE post questions in newsgroups, not directly to me ***
    *** PLEASE don't copy me on replies, I'll read them in the group ***

  4. Re: Only TCP segments that contains data have to be reordered ?

    Barry,

    Interesting argument, at least if a packet changes the sequence number
    it can be ordered.

    Although I agree with you all that SYN and FIN, besides packets that
    contains data have to be ordered, what are the places in RFC 793 that
    this is stated ?

    Thanks again


+ Reply to Thread