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Notable Replies

  1. system says:

    Very Nice lesson. Appreciate it!

  2. system says:

    how about hierarchical tocken bucket (HTB)? how many bucket that we use in HTB, and how the policier take the token from the bucket

  3. Hi Rene,
    Nice explanation. I have one query though.
    With the single rate tri colour policing, if we don't mention the bc and be values in the cli command, then they both are same. If we have a single burst which is exceeding bc value, then what will happen? Since be is also same as bc will the packet be dropped ( considering that this has violated ) or will the packet pass through if the number of tokens in bc+be is more than the burst arriving?

  4. Hi SP,

    When you use single rate three colour policing and don't specify the bc/be values then you will have two buckets that have the same size. When there are not enough tokens in the bc bucket, it will be empty and we will get some extra tokens from the be bucket...you are now exceeding.

    If you send a burst and there are not enough tokens in the bc+be buckets combined, that's when you are violating and your packet will be dropped.

  5. So if you defined Be = CIR/8 instead of CIR/32, this means that Be is now 4x larger. This means that you are allowed to store up more "credit" of unused traffic so you can burst more later. Keep in mind, that the average traffic rate, over a large period of time, will still be a maximum of the CIR rate, it is just now with a higher Be, you could potentially send 4x as much traffic in a short interval, if you had not been sending the full amount of traffic for previous intervals (hence you have "built up the credit").

    From a provider's point of view, this could result in a lot more "spikey" traffic (periods of small activity followed by a period of large activity). Most providers would prefer to have a more predicable traffic flow which is why, when Be is even an option with a Single Rate policer, it will almost always be set such the Be = Bc.

    Make sense?

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