From: Syed Mukhtar (snmukhtar@hotvoice.com)
Date: Sun Jun 01 2003 - 16:39:24 GMT-3
Jason,
Your understanding and explanation in the e mail is correct.
Just keep in mind that it may not always be possible to assign
exactly the same amount of bandwidth to different protocols/applications
using cusotmer queueing as asked in the exam. The idea is to
have some mechanism to provide some level of QoS.
Custom queueing does not provide a 100% control over how you
want to allocate bandwidth to different applications, but it
does a fairly good job. So you should not worry about not getting
the same exact ratios as asked in the question.
I hope that helps?
Syed
CCIE # 11513
On Sun, 1 Jun 2003 00:28:11 -0500
Jason Cash wrote:
>I am getting really confused on the custom queuing! I have
looked over the
>previously provided links, but those examples don't address
the problem I am
>having. Whereas I am instructed:
>
>
>
>IP traffic 30% bw
>
>SNA traffic 30% bw
>
>IPX traffic 25% bw
>
>Telnet traffic 15% bw
>
>
>
>Here is what I do (average pkt 1500)
>
>1) For each queue, divide the percentage of bandwidth you want
to allocate
>to the queue by the packet size, in bytes.
>
>30/1500 = .02
>
>30/1500 = .02
>
>25/1500 = .0166
>
>15/1500 = .01
>
>
>
>2) Normalize the numbers by dividing by the lowest number:
>
>..02/.01 = 2
>
>..02/.01 = 2
>
>..0166/.01 = 1.66
>
>..01/.01 = 1
>
>
>
>3) A fraction in any of the ratio values means that an additional
packet
>will be sent. Round up the numbers to the next whole number
to obtain the
>actual packet count.
>
>IP = 2
>
>SNA = 2
>
>IPX = 2
>
>Telnet = 1
>
>
>
>4) Convert the packet number ratio into byte counts by multiplying
each
>packet count by the corresponding packet size.
>
>IP = 1500x2 = 3000
>
>SNA = 1500x2 = 3000
>
>IPX = 1500x2 = 3000
>
>Telnet = 1500x1 = 1500
>
>
>
>Now here is one place I get lost. IPX byte count is the same
as IP and SNA
>and I know that can't be right, but what do I do? 2 is the
only multiple to
>go by.
>
>
>
>5) To determine the bandwidth distribution this ratio represents,
first
>determine the total number of bytes sent after all three queues are
>serviced:
>
>Based on my info above I get: 3000+3000+3000+1500= 10500
>
>
>
>6) Then determine the percentage of the total number of bytes
sent from each
>queue:
>
>IP = 3000/10500 = .28 (28%)
>
>SNA = 3000/10500 = .28 (28%)
>
>IPX = 3000/10500 = .28 (28%)
>
>Telnet = 1500/10500= .14 (14%)
>
>
>
>This adds up to 98%. So I will wait for some advice before
I proceed.
>Basically, when I a queue is rounded up and is equal to a greater
queue, how
>is that queues byte count determined?
>
>
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