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2.3.6- Afhtb

  

Next example is implemented by DS on Linux Distribution with the name Afhtb (originally Afcbq).  It's really a more complex example using RED queuing discipline. Implementing this example in Linux is not easy. Let's see how it works on Cisco.

Despite of the implementation problems the idea is truly simple; we have traffic from five DS classes: AF1, AF2, AF3, AF4 and BE. Each individual class should be limited to a rate of 1500 Kbps with a ceiling of 10 Mbps when traffic conditions allow. Classes AFx come in flavors AFx1, AFx2 and AFx3.  Then, you can have AF11, AF12, AF13, AF21, ..., AF43; twelve classes.
For each AFx? class we should implement a RED queuing discipline with the following parameters:

For a mark-probability of 0.06 denominator should be 16.66 and for a mark-probability of 0.4 denominator should be 2.5; but because Cisco doesn't admit decimal values we will use integer values as shown in the upper table.

What will be our approach?  We will use bandwidth command to limit bandwidth to each AFx class and then random-detect command to implement RED queuing discipline for each AFx? class.  Then type as follows in your Cisco router:
 

Really very easy.  Cisco DS implementation is very terse and we can build complex configurations using relatively very few commands. Have a look to Linux DS implementation to see how hard is implementing the Afhtb configuration.
Well, fellows, next example is ef-prio.
   

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