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delay- buffer-rate example

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  • 1.  delay- buffer-rate example

    Posted 10-28-2017 14:30

    Hi everyone,

    Just want  to  confim my understanding of the command " delay-buffer-rate" usage

     

    On MX5, delay buffer for shapers is calacuated as follows (assuming shaper is configued)

    100 msec * Shaped rate 

    For shaper at 20M

    100msec * 20^6=

     

    .1*20^6=2^6

    2000,000 bits or  200,000/8=250KBytes

     

    If we use delay-buffer-rate in traffic control profile i.e

    delay-buffer-rate  30M

    are we saying the delay buffer is based on same 100 msec time but we are using specified rate i.e 30M not the shaper rate i.e

     100 msec*30M= Delay buffer size?

     

     

    Thanks and have a nice weekend!!

     

     

     



  • 2.  RE: delay- buffer-rate example
    Best Answer

     
    Posted 10-29-2017 06:06

    Hi,

    Your understanding is correct.

    The delay-buffer rate overrides the shaping rate as the basis for the delay-buffer calculation. In other words, the shaping rate or scaled shaping rate is used for delay-buffer calculations only when the delay-buffer rate is not configured.

     

    https://www.juniper.net/documentation/en_US/junos11.1/topics/usage-guidelines/cos-oversubscribing-interface-bandwidth.html#id-11138786

     

    On Trio, you get 100ms worth of buffers if shaping-rate >= 1gbps and 500ms for shaping-rate < 1gbps


    delay-buffer-rate is independent of the guaranteed-rate and shaping-rate. It allows you to specify a rate to be used for delay-buffer calculations.  If you don’t configure delay-buffer-rate then guarateed-rate is used for iflset/ifl for delay-buffer calculations and shaping-rate for ifds.  For ifls and iflsets if guaranteed-rate-rate is not specified, the shaping-rate is used. If no rate is specified, port speed is used.

     

    Regards,

    Rahul