From: Ben (bmunyao@gmail.com)
Date: Tue Sep 25 2007 - 14:35:42 ART
Hi Jan
The question asked for the rate to average to 5Mbps, and be allowed to burst
up to 7.5Mbps.
MQC shaping conceptually uses a conform bucket and an excess bucket. The
conform bucket is replenished beginning of every Tc interval with Bc worth
of tokens. A packet is sent if its size is less or equal to the number of
tokens in conform bucket. When the traffic rate is below the average rate,
then at the beginning of each Tc, there would be left over tokens in conform
bucket. Since it is still replenished with Bc tokens, the left over tokens
spill to the excess bucket. These are the tokens used for exceeding the
average. i.e. when you use "shape average" command, then the rate can exceed
the average only after periods of sending rates below the average
HTH
Ben
On 9/25/07, jan vdb <jvdbro@yahoo.com> wrote:
>
> Hey Joseph,
>
> Must the shaping command not be SHAPE PEAK instead of shape
> average?
>
> Then we have a target rate of 7,5Mbps
> Traffic Shaping
> Target/Average Byte Sustain Excess Interval Increment
> Rate Limit bits/int bits/int (ms) (bytes)
> 7500000/5000000 30000 160000 80000 32 20000
>
> The solution in
> the book was indeed shape average but how can we have this excess burst
> then??
> Or am I missing something?
>
>
> ----- Original Message ----
> From: Joseph Brunner
> <joe@affirmedsystems.com>
> To: slevin kremera <slevin.kremera@gmail.com>; Cisco
> certification <ccielab@groupstudy.com>
> Sent: Tuesday, September 25, 2007
> 3:14:59 AM
> Subject: RE: iewb v4.1 lab 9 task 7.1 FRTS
>
> Let's look at the
> numbers first as given to us by the task
>
> AR = 7,500,000 bits per second
> CIR =
> 5,000,000 bits per second
> Tc = 32 ms
> Be = AR-CIR = 2,500,000
>
> So if we divide
> 1000ms / tc (32ms) we are given 31.25, now we just need to
> divide our cir by
> 31.25 to find our "bits per interval, sustained"
>
> So guess what?
>
> 5,000,000 /
> 31.25 = 160,000 (WHAT WE CAN SEND SUSTAINED PER TC)
>
> So now let's find our
> "bits per interval, excess" (BE)
>
> AR-CIR = 2,500,000 / 31.25 = 80000
>
> So the
> command under class class-default is
>
> shape average 5000000 160000 80000
>
> And
> we verify with... (look at the "interval")
>
> rack1r2#sh policy-map int s0/0
> Serial0/0
>
> Service-policy output: FRPOLICY
>
> Class-map: class-default
> (match-any)
> 2 packets, 148 bytes
> 5 minute offered rate 0 bps, drop
> rate 0 bps
> Match: any
> Traffic Shaping
> Target/Average
> Byte Sustain Excess Interval Increment
> Rate
> Limit bits/int bits/int (ms) (bytes)
> 5000000/5000000
> 30000 160000 80000 32 20000
>
> Adapt Queue
> Packets Bytes Packets Bytes Shaping
> Active Depth
> Delayed Delayed Active
> - 0 2 148 0
> 0 no
>
>
> -----Original Message-----
> From: nobody@groupstudy.com
> [mailto:nobody@groupstudy.com] On Behalf Of
> slevin kremera
> Sent: Monday,
> September 24, 2007 8:16 PM
> To: Cisco certification
> Subject: iewb v4.1 lab 9
> task 7.1 FRTS
>
> can some one explain how did he get the burst value of 160000
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