From: kongck (kongck@xxxxxxxxxxxxxx)
Date: Sat Jul 01 2000 - 06:25:29 GMT-3
hi Earl,
thanks for your reply,but to the example u took to us I think the CIR
should be 48000bps,MinCIR=16000bps,Bc=6000bits,Be=?(which I confused).
take a look at http://www.cisco.com/warp/customer/125/21.shtml#21-A
kck
> Here is something that I got from the archives
>
> Set the values of bc/be give the following conditions
> 1)Packets will be discarded if the traffic is more than 64kbps
> 2)DE bit will be set if the traffic is more than 48kbps
> 3)Slow down to 16kbps if BECN is received
> 4)Ts is 0.125
>
> First here are some definitions that I got from the frame relay forum.
>
> Bc----Committed Burst size is the maximum amount of data that the network
> agrees
> to transfer, under normal conditions, during a time interval Tc.
>
> Tc---- is the time interval during which the user can send only Bc and Be
> amount of data. In general, the duration of the Tc is proportional to the
> burstiness of the traffic. Tc is computed as Tc=Bc/CIR. Tc is not a
> periodic time interval. Instead, it is used only to measure incoming
data,
> during which it acts like a sliding window. Incoming data triggers the Tc
> interval, which continues until it completes its commuted duration.
>
> Be-----is the maximum amount of uncommitted data in excess of Bc that a
> frame relay network can attempt to deliver during a time interval Tc.
This
> data (be) generally is delivered with a lower probability than Bc. The
> network treats Be data as discard eligible.
>
> CIR---the committed rate at which the ingress access interface trunk
> interfaces, and egress access interface of a frame relay network transfer
> information to the destination frame relay end system under normal
> conditions. The rate is averaged over a minimum time interval Tc.
>
>
> The first condition tells you that the PVC is a 64Kbps circuit because
> everything will be discarded after it gets past 64k.
> The frame relay network treats Be data as discard eligible. If a BECN is
> received you go back to the CIR. We are given the Tc as Ts.
> Since Tc=Bc/CIR==>Bc=Tc * CIR=.125 * 16000=2000
> Be is the difference between total bandwidth allowed and the CIR and is
> allowed for the time interval of Tc.
> That gives us the equation (64000-16000)*.125=6000.
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