How to introduce delays for the TCP/IP responses?? - TCP-IP

This is a discussion on How to introduce delays for the TCP/IP responses?? - TCP-IP ; We have to introduce certain delay at the LDAP(TCP/IP) server and this should be done only while sending the response to a specific client. Can this be done using any TCP/IP parameters? We require this only for testing purpose i.e. ...

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Thread: How to introduce delays for the TCP/IP responses??

  1. How to introduce delays for the TCP/IP responses??

    We have to introduce certain delay at the LDAP(TCP/IP) server and this
    should be done only while sending the response to a specific client.
    Can this be done using any TCP/IP parameters? We require this only for
    testing purpose i.e. to check the client's behaviour for different time
    delays at the server.


  2. Re: How to introduce delays for the TCP/IP responses??


    wrote in message
    news:1157375465.463000.286100@h48g2000cwc.googlegr oups.com...
    > We have to introduce certain delay at the LDAP(TCP/IP) server and this
    > should be done only while sending the response to a specific client.
    > Can this be done using any TCP/IP parameters? We require this only for
    > testing purpose i.e. to check the client's behaviour for different time
    > delays at the server.
    >


    I've used dummynet to do this. I have a LiveCD of FreeBSD that I boot on a
    PC when I need to run it. It is relatively simple to set up and can be run
    on any spare PC or laptop.



  3. Re: How to introduce delays for the TCP/IP responses??

    What you can use is a pc with two interface cards and let it be a
    bridge.
    With the use of tc qdisc with parameters netem delay xx ms you can
    introduce delays in the traffic. Nice way to simulate WAN behaviour.


  4. Re: How to introduce delays for the TCP/IP responses??

    qazmlp1209@rediffmail.com wrote:
    > We have to introduce certain delay at the LDAP(TCP/IP) server and
    > this should be done only while sending the response to a specific
    > client. Can this be done using any TCP/IP parameters? We require
    > this only for testing purpose i.e. to check the client's behaviour
    > for different time delays at the server.


    Delays at the server, or delays in the network? The answer would be
    different for each.

    rick jones
    --
    The computing industry isn't as much a game of "Follow The Leader" as
    it is one of "Ring Around the Rosy" or perhaps "Duck Duck Goose."
    - Rick Jones
    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...

  5. Re: How to introduce delays for the TCP/IP responses??


    Rick Jones wrote:
    > qazmlp1209@rediffmail.com wrote:
    > > We have to introduce certain delay at the LDAP(TCP/IP) server and
    > > this should be done only while sending the response to a specific
    > > client. Can this be done using any TCP/IP parameters? We require
    > > this only for testing purpose i.e. to check the client's behaviour
    > > for different time delays at the server.

    >
    > Delays at the server, or delays in the network? The answer would be
    > different for each.

    I require delays for the responses coming out of the server.


  6. Re: How to introduce delays for the TCP/IP responses??


    qazmlp1209@rediffmail.com wrote:

    > I require delays for the responses coming out of the server.


    The easiest way would be to modify the source code to the server,
    assuming you have access to it.

    DS


  7. Re: How to introduce delays for the TCP/IP responses??


    David Schwartz wrote:
    > > I require delays for the responses coming out of the server.

    >
    > The easiest way would be to modify the source code to the server,
    > assuming you have access to it.

    The reason why I posted the question was because I do not have the
    access to the server source code : -(


  8. Re: How to introduce delays for the TCP/IP responses??


    easterman wrote:
    > What you can use is a pc with two interface cards and let it be a
    > bridge.
    > With the use of tc qdisc with parameters netem delay xx ms you can
    > introduce delays in the traffic. Nice way to simulate WAN behaviour.

    I understand that it can be used for introducing the delay at the
    routers. I hope it can be used at any server interface also directly.
    Where do I get this netem from?
    I have the following linux release:
    $more /etc/SuSE-release
    SUSE LINUX Enterprise Server 9 (x86_64)
    VERSION = 9

    How do I find whether netem is available in my machine? If not, where
    can I get the netem for the SuSE linux?


  9. Re: How to introduce delays for the TCP/IP responses??


    Noah Davids wrote:
    > I've used dummynet to do this. I have a LiveCD of FreeBSD that I boot on a
    > PC when I need to run it. It is relatively simple to set up and can be run
    > on any spare PC or laptop.

    Is dummynet available for the SuSE Linux release also? If yes, where
    can I get it from(Google does not help)?


  10. Re: How to introduce delays for the TCP/IP responses??

    qazmlp1209@rediffmail.com wrote:
    > Rick Jones wrote:
    >> qazmlp1209@rediffmail.com wrote:
    >> > We have to introduce certain delay at the LDAP(TCP/IP) server and
    >> > this should be done only while sending the response to a specific
    >> > client. Can this be done using any TCP/IP parameters? We require
    >> > this only for testing purpose i.e. to check the client's behaviour
    >> > for different time delays at the server.

    >>
    >> Delays at the server, or delays in the network? The answer would be
    >> different for each.

    > I require delays for the responses coming out of the server.


    So, you mean processing delays in the server rather than networking
    delays.

    You would not want to use something like dummynet or netem for that as
    they will delay all traffic, including ACKs and the like. You would
    then be inducing behaviour at TCP that would not match what would
    happen in "real life."

    What you want, if you can, is to interpose some code into the server
    application that recognizes a query for a specific client and delays
    giving it to the transport. This would be something outside the
    context of TCP/IP. It would be in the context of the LDAP code.
    Perhaps via LD_PRELOAD.

    rick jones
    --
    portable adj, code that compiles under more than one compiler
    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...

  11. Re: How to introduce delays for the TCP/IP responses??

    wrote in message
    news:1157545603.125194.180090@d34g2000cwd.googlegr oups.com...
    >
    > Noah Davids wrote:
    >> I've used dummynet to do this. I have a LiveCD of FreeBSD that I boot on
    >> a
    >> PC when I need to run it. It is relatively simple to set up and can be
    >> run
    >> on any spare PC or laptop.

    > Is dummynet available for the SuSE Linux release also? If yes, where
    > can I get it from(Google does not help)?
    >



    I do not believe so. But the nice thing about the live CD is that you can
    run it on any PC regardless of the OS installed, assuming that the PC will
    boot from a CD. Take a look at
    http://members.cox.net/~ndav1/self_p..._dummynet.html

    Note that you can introduce delays in only 1 direction.



  12. Re: How to introduce delays for the TCP/IP responses??


    qazmlp1209@rediffmail.com wrote:
    > easterman wrote:
    > > What you can use is a pc with two interface cards and let it be a
    > > bridge.
    > > With the use of tc qdisc with parameters netem delay xx ms you can
    > > introduce delays in the traffic. Nice way to simulate WAN behaviour.

    > I understand that it can be used for introducing the delay at the
    > routers. I hope it can be used at any server interface also directly.
    > Where do I get this netem from?
    > I have the following linux release:
    > $more /etc/SuSE-release
    > SUSE LINUX Enterprise Server 9 (x86_64)
    > VERSION = 9
    >
    > How do I find whether netem is available in my machine? If not, where
    > can I get the netem for the SuSE linux?


    I just use it from a knoppix live cd. Netem (net emulation) is an
    option of tc. What it does is introducing a delay at network level.
    Every packet is delayed for whatever you want milliseconds (other
    option also available).

    I thought, but am not sure, it is standard in linux 2.6 kernel, but by
    just using the tc command you can find out if your version supports it.
    If not an easy option is to use a knoppix live cd.

    If you need it I can post the settings I used


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