Frame relay traffic shaping

Discussion in 'Cisco' started by Toby, May 26, 2004.

  1. Toby

    Toby Guest

    As part of my steep learning curve I decided to investigate Traffic shaping.
    Only having an home lab using 3 2501 routers in this case I have a problem
    that I hope you lot can help with.

    I have connected my PC to R1 by 10 base Ethernet and using R2 as a
    FrameRelay switch and R3 as the remote router. all router connected by their
    serial ports. i.e I have the following set up.

    PC ----- E0-R1-S0.16----S0.16-R2-S1.17----S1.17-R3

    I have full connectivity (no problem there)

    My problem is I have set the link between R1 & R2 to 4000K and the link
    between R2 & R3 to 9.6K to create a bottle neck on purpose.

    I was hoping to be able to ping from either the PC or R1 to the loopback of
    R3 and experience packet drops with no traffic shaping but all I got was
    slow responce. This was due to there only being 1 TCP connection and of
    course it slowed down. All I achieved was timeouts due to the ping timer
    being set to 2 seconds. Increasing the timeout period proved no packets were

    What i need is a method of simulating multiple end users so that I will get
    drops and can play with traffic shaping and other QOS settings as a means of
    learning more in a practical way. This could be a program that creates and
    transmits data on multiple TCP connections or use UDP with no higher layer

    Has anyone come accross this sort of animal or wrote one themselves.


    Toby, May 26, 2004
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  2. Right, that is the whole point of queueing, to prevent drops :cool:

    The real us of traffic shaping is to dribble out traffic so that the frame
    relay switches won't activate policing. So you actually need to do
    "rate-limit" on the frame relay switch with "exceed-action drop" I don't
    know if rate-limit works on frame relay encapsulated packets.
    You might want to get your hands on ttcp. (test tcp) which is also built
    into the router.

    Remember that traffic originated by the router may get treated differently
    than transit traffic, depending on a host of factors.
    Phillip Remaker, May 27, 2004
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  3. Toby

    Toby Guest

    Thanks I hadn't heard of ttcp I will give it a go

    Toby, May 27, 2004
  4. Toby

    Hansang Bae Guest

    It requires enterprise IOS. And router generated packets are process
    switched so keep that in mind.



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    Hansang Bae, May 28, 2004
  5. Hello, Hansang!
    You wrote on Fri, 28 May 2004 01:19:07 GMT:

    HB> It requires enterprise IOS. And router generated packets are
    HB> process switched so keep that in mind.

    And the iperf is so much better than ttcp that there is no reason to use ttcp
    anymore. Unless Cisco box is the only equipment available on the other end, of

    With best regards,
    Andrey Tarasov, May 28, 2004
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