router buffering data before transferring it

Discussion in 'Cisco' started by A. Andrews, Feb 19, 2004.

  1. A. Andrews

    A. Andrews Guest

    Hello.

    We had a test lab set up with three 2621XM routers off of two of the
    routers are ASEtesters connected via serial to nm-16a.

    This is to simulate a RTU (remote terminal Unit) in the field (slave)
    and the master RTU. The three routers are connected in a triangle
    (mesh) with serial to serial configured at (as) a T1.


    Router B
    . .
    . .
    . .
    . .
    master---------Router A................Router C--------SlaveASE (RTU)
    ASE (RTU)

    Because the data wil be traversing over PLC (power line carrier) it
    will be at very low baud rates... 150 baud.

    I am seeing a problem.

    When the master polls the slave to send back its analog points the
    slave sends the data back to RouterC, however RouterC does not start
    sending the data to until it has all arrived.

    in a different test we replaced the ASE2000 test sets with
    hyperterminal.

    Router B
    . .
    . .
    . .
    . .
    PC-A---------Router A................Router C--------PC-Chyperterm
    hyperterm

    if I open a connection in hyperterm on PC-C to hyperterm on PC-A and
    begin to type I see what I am typing in PC-A. However the problem is
    again the router holds on the the data until I stop typing then it
    sends it.

    If I type just one character it gets send. however if I keep typing on
    PC-C I dont see anything on PC-A. When I stop typing all my characters
    get transfered.

    I would like RouterC to start sendsing data as soon as it recieves it

    Here is the config for RouterA asynch line 3
    line 3
    no motd-banner
    no exec-banner
    exec-timeout 0 0
    no flush-at-activation
    no activation-character
    no vacant-message
    modem InOut
    autocommand telnet RouterC /stream /source-interface loopback0
    special-character-bits 8
    transport output telnet
    escape-character NONE
    autohangup
    stopbits 1
    speed 150


    and for RouterC
    line 3
    no exec-banner
    exec-timeout 0 0
    no activation-character
    no vacant-message
    modem DTR-active
    special-character-bits 8
    no exec
    transport input telnet
    transport output none
    escape-character BREAK
    stopbits 1
    speed 150


    any ideas would be appreciated

    thx
    Alan
     
    A. Andrews, Feb 19, 2004
    #1
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  2. A. Andrews

    ETLALAR Guest

    It looks like sending/transmitting router uses Nagle algorithm for
    optimising perfomance.
    Do "show tcp" on sending router and look for Flags field.
    HTH,
    Cheers
    Alex

    "A. Andrews" <> wrote in message
    news:...
    > Hello.
    >
    > We had a test lab set up with three 2621XM routers off of two of the
    > routers are ASEtesters connected via serial to nm-16a.
    >
    > This is to simulate a RTU (remote terminal Unit) in the field (slave)
    > and the master RTU. The three routers are connected in a triangle
    > (mesh) with serial to serial configured at (as) a T1.
    >
    >
    > Router B
    > . .
    > . .
    > . .
    > . .
    > master---------Router A................Router C--------SlaveASE (RTU)
    > ASE (RTU)
    >
    > Because the data wil be traversing over PLC (power line carrier) it
    > will be at very low baud rates... 150 baud.
    >
    > I am seeing a problem.
    >
    > When the master polls the slave to send back its analog points the
    > slave sends the data back to RouterC, however RouterC does not start
    > sending the data to until it has all arrived.
    >
    > in a different test we replaced the ASE2000 test sets with
    > hyperterminal.
    >
    > Router B
    > . .
    > . .
    > . .
    > . .
    > PC-A---------Router A................Router C--------PC-Chyperterm
    > hyperterm
    >
    > if I open a connection in hyperterm on PC-C to hyperterm on PC-A and
    > begin to type I see what I am typing in PC-A. However the problem is
    > again the router holds on the the data until I stop typing then it
    > sends it.
    >
    > If I type just one character it gets send. however if I keep typing on
    > PC-C I dont see anything on PC-A. When I stop typing all my characters
    > get transfered.
    >
    > I would like RouterC to start sendsing data as soon as it recieves it
    >
    > Here is the config for RouterA asynch line 3
    > line 3
    > no motd-banner
    > no exec-banner
    > exec-timeout 0 0
    > no flush-at-activation
    > no activation-character
    > no vacant-message
    > modem InOut
    > autocommand telnet RouterC /stream /source-interface loopback0
    > special-character-bits 8
    > transport output telnet
    > escape-character NONE
    > autohangup
    > stopbits 1
    > speed 150
    >
    >
    > and for RouterC
    > line 3
    > no exec-banner
    > exec-timeout 0 0
    > no activation-character
    > no vacant-message
    > modem DTR-active
    > special-character-bits 8
    > no exec
    > transport input telnet
    > transport output none
    > escape-character BREAK
    > stopbits 1
    > speed 150
    >
    >
    > any ideas would be appreciated
    >
    > thx
    > Alan
     
    ETLALAR, Feb 20, 2004
    #2
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  3. A. Andrews

    AnyBody43 Guest

    "ETLALAR" <> wrote in message news:<c14v0j$g27$>...
    > It looks like sending/transmitting router uses Nagle algorithm for
    > optimising perfomance.
    > Do "show tcp" on sending router and look for Flags field.
    > HTH,
    > Cheers
    > Alex
    >
    > "A. Andrews" <> wrote in message
    > news:...
    > > Hello.
    > >
    > > We had a test lab set up with three 2621XM routers off of two of the
    > > routers are ASEtesters connected via serial to nm-16a.
    > >
    > > This is to simulate a RTU (remote terminal Unit) in the field (slave)
    > > and the master RTU. The three routers are connected in a triangle
    > > (mesh) with serial to serial configured at (as) a T1.
    > >
    > >
    > > Router B
    > > . .
    > > . .
    > > . .
    > > . .
    > > master---------Router A................Router C--------SlaveASE (RTU)
    > > ASE (RTU)
    > >
    > > Because the data wil be traversing over PLC (power line carrier) it
    > > will be at very low baud rates... 150 baud.
    > >
    > > I am seeing a problem.
    > >
    > > When the master polls the slave to send back its analog points the
    > > slave sends the data back to RouterC, however RouterC does not start
    > > sending the data to until it has all arrived.
    > >
    > > in a different test we replaced the ASE2000 test sets with
    > > hyperterminal.
    > >
    > > Router B
    > > . .
    > > . .
    > > . .
    > > . .
    > > PC-A---------Router A................Router C--------PC-Chyperterm
    > > hyperterm
    > >
    > > if I open a connection in hyperterm on PC-C to hyperterm on PC-A and
    > > begin to type I see what I am typing in PC-A. However the problem is
    > > again the router holds on the the data until I stop typing then it
    > > sends it.
    > >
    > > If I type just one character it gets send. however if I keep typing on
    > > PC-C I dont see anything on PC-A. When I stop typing all my characters
    > > get transfered.
    > >
    > > I would like RouterC to start sendsing data as soon as it recieves it
    > >
    > > Here is the config for RouterA asynch line 3
    > > line 3
    > > no motd-banner
    > > no exec-banner
    > > exec-timeout 0 0
    > > no flush-at-activation
    > > no activation-character
    > > no vacant-message
    > > modem InOut
    > > autocommand telnet RouterC /stream /source-interface loopback0
    > > special-character-bits 8
    > > transport output telnet
    > > escape-character NONE
    > > autohangup
    > > stopbits 1
    > > speed 150
    > >
    > >
    > > and for RouterC
    > > line 3
    > > no exec-banner
    > > exec-timeout 0 0
    > > no activation-character
    > > no vacant-message
    > > modem DTR-active
    > > special-character-bits 8
    > > no exec
    > > transport input telnet
    > > transport output none
    > > escape-character BREAK
    > > stopbits 1
    > > speed 150
    > >
    > >
    > > any ideas would be appreciated
    > >
    > > thx
    > > Alan


    Hi,

    This reminds me of something I worked on a few years ago.

    The customer wanted to transport serial data from some Trend
    Controls Building control equipment over an Ethernet LAN. The building
    control stuff has proprietory L2/L3 protocols that ran over point
    to point rs232 serial links.

    http://www.trend-controls.com/General/English.nsf/Docs/Homepage
    May well have been the control system company.

    They wanted to use terminal servers to do the job in a very
    similar configuration to yours. Trend recommended a particular make
    whose name now escapes me but the end user wanted to use big name
    networking kit. Anyway to cut a long story short it did not work
    because of the way the big name kit packetised the serial data.

    In our case it sent data every 100ms (IIRC). This broke the Trend
    protocols which assumed that a delay of this size between bytes
    was an indication of a loss of connectivity.

    Anyway, my helpful point is that the Terminal servers that
    Trend Controls recommended could not have behaved in this way.

    Unfortunately I cannot recall the name of the company but if
    you called up Trend Controls and pretended to have some 8 year
    old kit and asked for a recommendation for a terminal server you
    might be in business.

    We were at our wits end trying to make it go, for the first (and
    only) time I was looking at RS232 data with an OSCILLOSCOPE?!?!?!
    I think we even had some soldering irons out at some stage 'cos
    the "RS232" turned out to be RS232ish but using TTL levels.


    This may have been the beast.
    "ID202:- The Trend ID202 Access controller provides "out of the box"
    functionality, is easy to install and use, and can operate in stand
    alone mode or be connected to an ID200 Supervisor via the Trend
    network. If needed, a wide range of peripherals can be connected to
    the controller, enabling most retrofit applications to utilise
    existing readers, cards and locks. Whatever the size of the system,
    the simple modular construction ensures easy installation and
    intuitive operation."

    Yes call them up and say that you want to run this stuff over Ethernet
    and ask for suggestions.

    Alternatively IIRC the DEC terminal servers that we investigated
    that sent a packet every 100ms and may well do the job you want
    since at 150bps that would be at most two bytes in a packet.

    Of course there may be a configuration tweak for the cisco kit.

    If you REALLY, really want to do this you might consider
    writing your own code say for a linux box. Does not sound
    too hard.

    Repeat
    Wait for byte
    Send packet
    For ever


    Good LUCK.
     
    AnyBody43, Feb 21, 2004
    #3
  4. A. Andrews

    News Account Guest

    Try "no service nagle"

    Don Woodward


    "A. Andrews" <> wrote in message
    news:...
    > Hello.
    >
    > We had a test lab set up with three 2621XM routers off of two of the
    > routers are ASEtesters connected via serial to nm-16a.
    >
    > This is to simulate a RTU (remote terminal Unit) in the field (slave)
    > and the master RTU. The three routers are connected in a triangle
    > (mesh) with serial to serial configured at (as) a T1.
    >
    >
    > Router B
    > . .
    > . .
    > . .
    > . .
    > master---------Router A................Router C--------SlaveASE (RTU)
    > ASE (RTU)
    >
    > Because the data wil be traversing over PLC (power line carrier) it
    > will be at very low baud rates... 150 baud.
    >
    > I am seeing a problem.
    >
    > When the master polls the slave to send back its analog points the
    > slave sends the data back to RouterC, however RouterC does not start
    > sending the data to until it has all arrived.
    >
    > in a different test we replaced the ASE2000 test sets with
    > hyperterminal.
    >
    > Router B
    > . .
    > . .
    > . .
    > . .
    > PC-A---------Router A................Router C--------PC-Chyperterm
    > hyperterm
    >
    > if I open a connection in hyperterm on PC-C to hyperterm on PC-A and
    > begin to type I see what I am typing in PC-A. However the problem is
    > again the router holds on the the data until I stop typing then it
    > sends it.
    >
    > If I type just one character it gets send. however if I keep typing on
    > PC-C I dont see anything on PC-A. When I stop typing all my characters
    > get transfered.
    >
    > I would like RouterC to start sendsing data as soon as it recieves it
    >
    > Here is the config for RouterA asynch line 3
    > line 3
    > no motd-banner
    > no exec-banner
    > exec-timeout 0 0
    > no flush-at-activation
    > no activation-character
    > no vacant-message
    > modem InOut
    > autocommand telnet RouterC /stream /source-interface loopback0
    > special-character-bits 8
    > transport output telnet
    > escape-character NONE
    > autohangup
    > stopbits 1
    > speed 150
    >
    >
    > and for RouterC
    > line 3
    > no exec-banner
    > exec-timeout 0 0
    > no activation-character
    > no vacant-message
    > modem DTR-active
    > special-character-bits 8
    > no exec
    > transport input telnet
    > transport output none
    > escape-character BREAK
    > stopbits 1
    > speed 150
    >
    >
    > any ideas would be appreciated
    >
    > thx
    > Alan
     
    News Account, Feb 22, 2004
    #4
  5. A. Andrews

    Konstantin Guest

    Why are you still using such unhandy thing as Hyper Terminal? Recently
    I've found an interesting program - Flash Terminal. It is really Hyper
    Terminal killer. With Flash Terminal you can chat and exchange files
    via modem (including v.90, ISDN, ADSL, GPRS) and null-modem
    simultaneously without Internet! You can exchange up to 255 files at
    once with unlimited transfer resuming after connection break. Program
    includes large amount of nice avatars.
    Direct link for downloading:
    http://www.qwertystudios.com/FlashTerminalSetup.zip
    Direct link for Win95 version downloading:
    http://www.qwertystudios.com/FlashTerminalSetup_w95.zip
    Developers site:
    http://www.qwertystudios.com/
    More info:
    http://www.qwertystudios.com/products.php.html
     
    Konstantin, Feb 26, 2004
    #5
  6. A. Andrews

    A. Andrews Guest

    "News Account" <> wrote in message news:<CRa_b.5816$>...
    > Try "no service nagle"
    >
    > Don Woodward
    >
    >



    I resolved the problem by decreasing the buffer-length serring on the
    asynch line from 1536 bytes to 16.

    Works like a charm
     
    A. Andrews, Feb 26, 2004
    #6
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