From: Narbik Kocharians (narbikk@gmail.com)
Date: Mon Jun 30 2008 - 02:39:33 ART
When you need to shape the traffic, there are two types of shaping available
to you:
*Average rate shaping:* Average rate shaping limits the transmission rate to
the CIR. Using the CIR ensures that the average amount of traffic being sent
conforms to the rate expected by the network.
*Peak rate shaping:* Peak rate shaping configures the router to send more
traffic than the CIR. To determine the peak rate, the router uses the
following formula:
*Peak rate = CIR(1+Be/Bc)*
Remember that with Shape Peak, shaping allows the router to burst higher
than average rate shaping. However, the traffic sent above the CIR *CAN* be
dropped if the network becomes congested.
On Sun, Jun 29, 2008 at 8:31 PM, Huan Pham <Huan.Pham@peopletelecom.com.au>
wrote:
> I am not sure about using shape peak command. Appreciate if someone can
> share some clarification.
>
> The most confusing fact is that if you configure "shape peak 512000",
> without optional Bc and Be parrameters (i.e. using default), you are
> actually allow traffic to burst to 1024K (double the configured rate).
>
>
> R5#
> !
> policy-map SHAPE
> class WEB
> shape peak 512000
>
> int s0/0
> service-policy output SHAPE
>
> R5# sh policy-map int s0/0
>
> Serial0/0
>
> Service-policy output: SHAPE
>
> Class-map: WEB (match-all)
> 0 packets, 0 bytes
> 5 minute offered rate 0 bps, drop rate 0 bps
> Match: protocol http
> Traffic Shaping
> Target/Average Byte Sustain Excess Interval
> Increment
> Rate Limit bits/int bits/int (ms) (bytes)
>
> 1024000/512000 3200 12800 12800 25 3200
>
>
> Adapt Queue Packets Bytes Packets Bytes Shaping
> Active Depth Delayed Delayed Active
> - 0 0 0 0 0 no
>
> Class-map: class-default (match-any)
> 223 packets, 2899 bytes
> 5 minute offered rate 0 bps, drop rate 0 bps
> Match: any
>
>
>
> So how will you best answer this question?
>
> Assign WEB traffic the minimum of 128K, and allow it to peak at 512K.
>
>
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>
>
>
>
>
-- Narbik Kocharians CCSI#30832, CCIE# 12410 (R&S, SP, Security) www.Net-Workbooks.com Sr. Technical Instructor
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