Difference between revisions of "Manual:Queues - PCQ"

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==Classifiers==
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==Classification Examples==
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To better understand classification we will take a list of 18 packet streams from specific address and port to a specific address and port. Then we will choose a classifier and divide all 18 packet streams into PCQ sub-streams 
  
 
[[Image:PCQ_Example1.png|700px|Classifiers]]
 
[[Image:PCQ_Example1.png|700px|Classifiers]]
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[[Image:PCQ_Example2.png|700px|Classifiers]]
 
[[Image:PCQ_Example2.png|700px|Classifiers]]
  
==Limit and Total Limit==
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==PCQ Rate Examples==
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Here it is possible to see what happened if PCQ-rate is or isn't specified. I must note that if both limits (pcq-rate and max-limit) are unspecified, queue behavior can be inprecise. I  it is strongly suggested to have at least one of these options specified.
  
  
 
[[Image:PCQ3.png|500px|Classifiers]]
 
[[Image:PCQ3.png|500px|Classifiers]]
[[Image:PCQ4.png|500px|Classifiers]]
 
  
  
==Rate==
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[[Image:PCQ4.png|500px|Classifiers]]
  
  
 
[[Category:Manual]]
 
[[Category:Manual]]
[[Category:Unfinished]]
 

Revision as of 17:25, 4 December 2008

Usage

PCQ was introduce to optimize massive QoS systems where most of the queues was exactly the same only for different sub-streams. For example a sub-stream can be download or upload for one particular client (IP) of connection to server.

PCQ algorithm is very simple - at first it uses selected classifiers to distinguish one sub-stream from another, then applies individual FIFO queue size and limitation on every sub-stream (witch is exactly the same for every sub-stream), then group all sub-streams together and apply global FIFO queue size and limitation.

PCQ parameters:

  • pcq-classifier (dst-address | dst-port | src-address | src-port; default: "")  : selection of sub-stream identifiers
  • pcq-rate (number) : maximal available data rate of each sub-steam
  • pcq-limit (number) : queue size of one sub-stream in packets
  • pcq-total-limit (number) : queue size of global FIFO queue


PCQ Algorithm


So instead of having 100 queues with 1000kbps limitation for download we can have one PCQ queue with 100 sub-streams


Classification Examples

To better understand classification we will take a list of 18 packet streams from specific address and port to a specific address and port. Then we will choose a classifier and divide all 18 packet streams into PCQ sub-streams

Classifiers

Classifiers

PCQ Rate Examples

Here it is possible to see what happened if PCQ-rate is or isn't specified. I must note that if both limits (pcq-rate and max-limit) are unspecified, queue behavior can be inprecise. I it is strongly suggested to have at least one of these options specified.


Classifiers


Classifiers