From: Kyle Galusha (kgalusha@xxxxxxxxx)
Date: Sat Jul 01 2000 - 13:37:10 GMT-3
meant to send this to the group..here it is again.
Just to add to the topic (although slightly off topic). Most of the time when
I discuss F/R traffic shapping I talk about modifying Bc to reduce the length
of the time interval on a given or group of PVCs. By default (If I remember c
orrectly) the CIR defaults to 56K and the time interval is 125ms and the Bc is
7000. If we are dealing with voice traffic, 125 msec is a too long of an inte
rval to wait for the next frame of voice so I make Bc smaller (or make link/int
erface speed greater) so that time interval for sending data is less (say under
60 msec).
I use sho traffic-shap to monitor the time interval as I make changes.
Correct me if my default CIR is wrong.
Kyle
At 05:59 PM 6/30/2000 -0400, Vijaykrishna wrote:
>
>About the ex. in 12.1 I think the line may use upto 128K burst for the
>100msec and NOT T1 because
>by the calculcation--
>
>Tc interval = 0.1sec
>Bc = 6400 bits
>Be = 6400 bits
>CIR = Bc/Tc = 64000
>EIR = Be/Tc = 64000
>PIR = CIR+EIR = 128K RATE of traffic only for Tc interval
>
>Similarly considering the above calculation for the ex. in 12.0 should be
>
>traffic-shap rate 64000 8000 184000
>
>where 184000 = (1536000/8) - 8000 so this shaping allows link to burst at
>T1 rate for the first interval.
>but again I don't get how to fit the 30 sec part.
>however 46080000=1536000*30 ie. T1 rate * 30 sec.
>
>Can anyone pl explain this better ??
>
>Vijay
>-----Original Message-----
>From: Sam Li <sxl099@hotmail.com>
>To: ccielab@groupstudy.com <ccielab@groupstudy.com>
>Date: Friday, June 30, 2000 4:27 PM
>Subject: Frame Relay Traffic Shape
>
>
>>I am puzzled on traffic shaping. I don't have problem on what commands to
>>use. I just could not figure out where do you get all parameters used in
>the
>>command.
>>
>>I tracked back the archive of the mailing list, i.e. at
>>
>>http://www.groupstudy.com/archives/ccielab/200005/msg00050.html
>>I think the parameters posted at fatkid.com
>>("traffic-shape group 101 16000 32000 32000 1000")
>>are ok to serve the purpose although it is confusing because of the same
>>number as 32kbps and not good because of using two second as the interval.
>>
>>
>>I would use
>>traffic-shape group 101 16000 2000 2000 which is 1/8 second as the
>interval.
>>
>>In the same email mentioned the some helpful info on CCO, what is the url?
>>
>>I check on the cisco manuals for better answer. Here is what I find.
>>
>>
>>*****************12.0 manual *************************
>>at
>>http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/12cgcr/qos_
>c/qcpart4/qcgts.pdf
>>
>>QC-101 to 102
>>
>>It states
>>
>>Constrained Access Rate Example
>>In this example, a customer may use all of a T1 line for 30 seconds in a
>>burst, but the long-term average is limited to 64 kbps. This configuration
>>restricts the amount of load the system can induce on the outbound network
>>interface.
>>
>>interface <his interface or sub-interface>
>>traffic-shape rate 64000 8000 46080000
>>
>>
>>If you need to restrict the amount of load the system can induce both
>>outbound and inbound, and therefore the total load it can induce on the
>>Internet Service Provider (ISP), configure traffic shaping on both the
>>inbound and outbound interfaces, as in the following example:
>>
>>interface <serial interface or sub-interface>
>>traffic-shape rate 64000 8000 46320000
>>interface <LAN interface>
>>traffic-shape rate 64000 8000 46320000
>>
>>
>>****************** 12.1 Manual *****************
>>
>>at
>>http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/qos
>_c/qcprt4/qcdgts.pdf
>>
>>page QC-135
>>
>>Constrained Access Rate Example
>>In this example, a T1 line may be used for 100 milliseconds in a burst, but
>>the long-term average is limited to 64 kbps. This configuration example
>>restricts the amount of load the system can induce on the outbound network
>>interface.
>>
>>interface serial 4/1:0
>>traffic-shape rate 64000 6400 6400
>>
>>
>>If you need to restrict the amount of load the system can induce outbound,
>>and therefore the total load it can impose on the Internet service provider
>>(ISP), configure traffic shaping on the outbound interfaces.
>>
>>
>>**********
>>
>>I think the parameters used in 12.0 manual were wrong and in 12.1 were
>>correct. I think on 12.0 manual it should be
>>
>>interface <his interface or sub-interface>
>>traffic-shape rate 64000 8000 440000 but that has nothing to with "30
>>second".
>>
>>44000=1544000/8-8000
>>
>>I especially don't understand how do they get the parameters for the ISP
>>example in 12.0 manual showed above.
>>
>>Maybe that is why they don't use that example in 12.1 manual any more.
>>
>>Could someone explain what do I miss?
>>
>>If the lab ask you to "a customer may use all of a T1 line for 30 seconds
>in
>>a burst, but the long-term average is limited to 64 kbps"
>>
>>What interval you are going to use? how does the "30 seconds" get into the
>>calculation?
>>
>>How sorry it will be if you know all commands but can't figure out the
>>numbers to fill in!
>>
>>
>>
>>Thanks in advanced,
>>
>>
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