TCP for transaction

From: kfl (kfl_at_xiphos.ca)
Date: 05/28/03

  • Next message: kfl: "TCP for transaction" 
    To: "freebsd - net" <freebsd-net@freebsd.org>
Date: Wed, 28 May 2003 13:32:14 -0400

    Hi,
            Here is a tcpdump output from one FreeBSD box with TCP for transaction
    enabled and a client supporting the NOPUSH setsockopt with a windows box:

    19:00:15.357281 192.168.3.200.1247 > 192.168.2.7.microsoft-ds: SP
    4208572194:420
    8572331(137) win 65535 <mss 1460,nop,wscale 2,nop,nop,ccnew 2> (DF)
    19:00:15.357514 192.168.2.7.microsoft-ds > 192.168.3.200.1247: S
    2795532295:2795
    532295(0) ack 4208572195 win 61680 <mss 1460,nop,wscale 2> (DF)
    19:00:15.357911 192.168.3.200.1247 > 192.168.2.7.microsoft-ds: . ack 1 win
    52560
     (DF)
    19:00:18.356736 192.168.3.200.1247 > 192.168.2.7.microsoft-ds: P 1:138(137)
    ack
    1 win 52560 (DF)
    19:00:18.357465 192.168.2.7.microsoft-ds > 192.168.3.200.1247: P 1:90(89)
    ack 13
    8 win 61646 (DF)
    19:00:18.456659 192.168.3.200.1247 > 192.168.2.7.microsoft-ds: . ack 90 win
    5256
    0 (DF)
    19:00:20.611227 192.168.3.200.1247 > 192.168.2.7.microsoft-ds: P
    138:336(198) ac
    k 90 win 52560 (DF)
    19:00:20.612037 192.168.2.7.microsoft-ds > 192.168.3.200.1247: P 90:359(269)
    ack
     336 win 61597 (DF)

    I see two problems here (in fact its only one problem with a side effect):

            1) When sending the ccnew option T/TCP send data with it.
            2) As a results the sender times out and retransmit at 19:00:18.356736
               adding 3 seconds to the connection data transfer.

    Now, in the rfc1644 it is stipulated that a host can send data with the
    cc.new option. I am a bit confused here since T/TCP should accelerate data
    transfer for small transaction (saving 1 RTT) and not timing out if the
    destination host does not support it.

            I think we should avoid sending data with the cc.new option.

    Any thoughs?

    Karim.

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  • Next message: kfl: "TCP for transaction"

    Relevant Pages

    • FW: TCP for transaction
      ... > transaction enabled and a client supporting the NO_PUSH ... > setsockopt with a windows box: ... > 90:359ack ... > RTT) and not timing out if the destination host does not support it. ...
      (freebsd-net)
    • TCP for transaction
      ... enabled and a client supporting the NO_PUSH setsockopt with a windows box: ... I am a bit confused here since T/TCP should accelerate data ... destination host does not support it. ...
      (freebsd-net)
    • TCP for transaction
      ... enabled and a client supporting the NOPUSH setsockopt with a windows box: ... I am a bit confused here since T/TCP should accelerate data ... destination host does not support it. ...
      (freebsd-net)