From: Rick (ccie_2003@hotmail.com)
Date: Fri Sep 20 2002 - 16:19:24 GMT-3
Can someone just explain why we even have to set the normal burst and excess
burst?
Here is a excerpt from the doc cd
Testing of TCP traffic suggests that the chosen normal and extended burst
values should be on the order of several seconds worth of traffic at the
configured average rate. That is, if the average rate is 10 Mbps, then a
normal burst size of 10 to 20 Mbps and an Excess Burst size of 20 to 40 Mbps
would be appropriate.
We recommend the following values for the normal and extended burst
parameters:
normal burst = configured rate * (1 byte)/(8 bits) * 1.5 seconds
extended burst = 2 * normal burst
With the listed choices for parameters, extensive test results have shown
CAR to achieve the configured rate. If the burst values are too low, then
the achieved rate is often much lower than the configured rate.
Thanks,
Rick
----- Original Message -----
From: "Rick" <ccie_2003@hotmail.com>
To: "Ccielab (E-mail)" <ccielab@groupstudy.com>
Sent: Friday, September 20, 2002 1:41 PM
Subject: CAR question for QOS expert
> Lets say I want to rate limit a connection to 15Mbs on a 45Mbs interface.
I
> looking a Cisco example and it shows they have the burst normal and burst
> exceed allowing 2,812,500 bytes. Why must we have the burst statements. If
you
> bought a tiered 15Meg connection from a ISP, aside from frame-relay you
don't
> get any more BW than you pay for right? I'm just trying to relate this to
> something because I don't understand the burst statements. Can someone
please
> explain. I have read about the token bucket and all, but I'm a litte
confused.
> Here is the syntax of the example I was looking at.
> int HSSI 0/0/0
> rate-limit output 15000000 2812500 5625000 conform-action transmit
> exceed-action drop
> ip add 10.1.0.9 255.255.255.0
>
> On a side note, How does one remember all this QOS stuff..??? I guess the
> trick is once you learn it you must know where to reference it on the DOC
CD.
>
> Thanks and Good Luck to all!
> Rick
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