"wrr-queue queue-limit" command - BIG CONFUSION

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Nov 29th, 2007
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Guys,


Please can someone let us kow a couple of things about this command.


1. Is this command setting a percentage of the port buffer (say 14MB for TX on a WS-X6704-10GE) or a weight of the buffer space. Cisco documentation says weight, but SRND says its a percentage?


2. What is the default percentage of the priority queue for for various port types? is it 15% or 30%


3. in the following URL


http://www.cisco.com/en/US/products/hw/switches/ps708/products_white_paper09186a0080131086.shtml


lets say again for the WS-X6704-10GE card on transmit, it has the following TX Queue Sizes, are these just defaults that can be set with the "wrr-queue queue-limit" command?


Tx Queue Sizes

SP-2.2MB

Q7-10KB

Q6-10KB

Q5-10KB

Q4-10KB

Q3-2.2MB

Q2-2.9MB

Q1-7.2MB



This is not very clear atall and if anyone has experience of this, pls could you help.


Many thx,

Ken

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kfarrington Thu, 11/29/2007 - 10:47
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Also, another important factor that ties into this from the SRND is the following



For CatOS, you specifically set the PQ so even if this was percentage or ratio, this would eqaute to the same figure

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Example 2-75 Catalyst 6500 (PFC3) CatOS-1P3Q8T Queuing Example


CAT6500-PFC3-CATOS> (enable) set qos txq-ratio 1p3q8t 5 25 40 30

! Allocates 5% for Q1, 25% for Q2, 40% for Q3 and 30% for Q4 (PQ)

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but for IOS, you donot set the PQ queue-limit (see below), so is the command below, a weighted ratio, ie 5 over 70 (3.5%), 25 over 70 (17.5%) and 40 over 70 (28%)


or the actual percentage figure?


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Example 2-76 Catalyst 6500 IOS-1P3Q8T Queuing Example


CAT6500-PFC3-IOS(config)# interface range GigabitEthernet1/1 - 48

CAT6500-PFC3-IOS(config-if)# wrr-queue queue-limit 5 25 40

! Allocates 5% for Q1, 25% for Q2 and 40% for Q3

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Many thx indeed,

Ken

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