Convert bytes to MB on cisco router

Discussion in 'Cisco' started by tlanum, Mar 29, 2006.

  1. tlanum

    tlanum Guest

    when doing a sho int atm and looking at the output.

    Example

    143849529 packets input, 129326779238 bytes
    125183986 packets output, 29173768997 bytes
    there is a way to convert this to actual Mb/s

    Does someone know the calculation to achieve this
     
    tlanum, Mar 29, 2006
    #1
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  2. On 29.03.2006 22:59 wrote
    Take the minimum of 'Last clearing of "show interface" counters' and
    'uptime' and do the math,
     
    Arnold Nipper, Mar 29, 2006
    #2
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  3. On sufficiently new high-end devices you could probably
    put together some TCL code that did the conversion for you.

    The figures you gave are not enough information to calculate
    Mb/s -- to calculate that, you need the time interval as
    well as the volume difference.

    You should decide "which" Mb/s you mean. Does your prefix 'M'
    mean "million" (10^6), or does it mean the same "mega" that is
    used to measure memory, 1024*1024*1024 (i.e., 2^30) ?

    Also, because of inconsistant usage, you should decide if you
    want megabits per second or megabytes per second.


    I would suggest that possibly the easiest thing for you to do
    would be to set up MRTG monitoring of the device, and let it
    take the measurements and do the calculations and keep the nice
    historical trend graphs. It usually isn't very useful to know
    that the average traffic rate *since the device was last reset*
    was something-or-other -- typically the low evening and weekend
    figures distort those figures completely. You probably want to
    get a good idea of what your peak rates are at various times:
    MRTG and similar are great for that.
     
    Walter Roberson, Mar 29, 2006
    #3
  4. tlanum

    Merv Guest

    If you are just trying to get a traffic snapshot,
    then clear the interface counters and then do
    a show clock and a show interface together
    (cut and paste from notepad)
    wait several minutes and repeat. subtract the
    traffic and the clock times and do the math.

    you can also configure "load-interval 30" on the interface
    and then it will give you traffic average for a 30 second period
    as seen in the output of show interface
     
    Merv, Mar 30, 2006
    #4
  5. Short answer... there is 8 bits to 1 bytes.

    Covert bits to bytes: divide the megabits by 8
    Covert bytes to bits: multiple the megabytes by 8
     
    Joel Salminen, Mar 30, 2006
    #5
  6. Please re-examine the information the OP has available.
    It is in packets and bytes. There is no megabits or megabytes
    on it, so neither of your calculations would apply.

    Your calculations are also not correct as phrased. One does not
    convert "bits" to "bytes" by dividing megabits by 8. Dividing
    megabits by 8 would yeild megabytes, not bytes.

    But the OP wanted "Mb/s". As I indicated in my earlier posting,
    one first has to resolve what "Mb/s" means. "Mb/s" is sometimes
    used for "megabits per second", and sometimes for "megabytes per
    second" (but not correctly). In turn "megabits" might refer to
    one million bits (10^6), or it might refer to "mega" as in the
    use in computer memory, which is 1024*1024*1024 (2^30).

    Once one has decided what "Mb/s" means, one will need a time
    interval in order to do the appropriate calculation. Scaling
    the data the OP showed by 8 cannot yield megabits PER SECOND.
     
    Walter Roberson, Mar 30, 2006
    #6
  7. tlanum

    TLan Guest

    ok then i had this wrong. I thought this was the avg throughput at that
    point in time on that interface. an engineer at AT&T informed me but I
    must have misheard him.

    I have setup MRTG so not an issue anymore

    also Mb/s in my topic was meant as megabits per second.
     
    TLan, Mar 30, 2006
    #7
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