frame-relay traffic-rate

Discussion in 'Cisco' started by Matt, Jan 27, 2007.

  1. Matt

    Matt Guest

    I am studying Frame relay traffic shaping and have a question about how
    the "frame-relay traffic-rate" command figures the Byte Limit as
    displayed in the "show frame pvc xxx" or the "show traffic-shape"
    commands. If I set "frame-relay traffic-rate 64000 64000", a "show
    traffic-shape" shows a Byte Limit of 1000 which is essentially the size
    of my token bucket. With no additional peak rate configured, the Be is
    0 and Bc is 8000 bits/int, with tc = 125ms. So my byte limit is 8000/8
    = 1000 bytes/int. Now if you change the command to "frame-relay
    traffic-rate 64000 96000" the Byte Limit becomes 5000. This is where I
    don't quite understand how it is coming up with that number. The cisco
    docs say the following about this command:

    "For example, entering the frame-relay traffic-rate 64000 96000 command
    will result in a CIR of 64000 bps. Assuming 8 intervals of 125
    milliseconds, the Bc is 64000/8 or 8000 bits. The Be value is
    calculated by subtracting 64000 from 96000, so the one-second value is
    32000 bits. For each 125-millisecond interval, the Be value is 4000
    bits."
    from:
    http://www.cisco.com/univercd/cc/td/doc/product/software/ios124/124tcr/twan_r/wan_f2ht.htm#wp1083344

    So if the Be is 4000 bits/int, that would be 500 bytes/int. If the
    byte limit for a CIR of 64000 with no Be is 1000 bytes/int, then I
    would think adding a Be of 4000 bits/int would make the Byte Limit 1500
    rather than 5000.

    All of the books I've read and Cisco's doc's seem to be in agreement
    that the Be is 4000 bits/interval. So I don't understand how 4000
    bits/int can translate to a 4000 byte/int increase in the Byte limit.
    What am I missing?

    Thanks in advance for any help,
    Matt
     
    Matt, Jan 27, 2007
    #1
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