From: Narbik Kocharians (narbikk@gmail.com)
Date: Sat Nov 22 2008 - 19:51:02 ARST
Huan,
Yep i see your point.
On Sat, Nov 22, 2008 at 1:05 PM, But Nicky <lyredhair@gmail.com> wrote:
> You guys,
> I absolutely agree with you guys, there is an error example in docCD.
>
>
> On Sun, Nov 23, 2008 at 2:16 AM, darth router <darklordrouter@gmail.com
> >wrote:
>
> > That's the way it works.
> >
> > Would be nice if someone was to exactly explain why cisco created that
> > command and did it that way. I think it has to do with an arrangement
> with
> > your provider. Say, they guarantee you a rate of 512, but allow you a
> peak
> > rate of 1024, but if there is congestion, they will be able to drop that
> > 2nd
> > 512 of data. Regardless, your sending 1024 per interval. So depending on
> > how
> > you marked your traffic, certain classes in that first 512 would be safe,
> > and anything else would be fair game for the service provider bit bucket
> in
> > case of congestion.
> >
> > On Sat, Nov 22, 2008 at 9:59 AM, Hobbs <deadheadblues@gmail.com> wrote:
> >
> > > Anyways, after all that yes I agree with your solution. I wonder what
> the
> > > experts think...
> > >
> > > On Sat, Nov 22, 2008 at 11:51 AM, Hobbs <deadheadblues@gmail.com>
> wrote:
> > >
> > > > Ok. I think I understand this a little better. Whether you configure
> > > "peak"
> > > > or "average" the following value is still always CIR. This will
> always
> > be
> > > > the "average rate". You target rate will be set using default values
> if
> > > you
> > > > do not specify a Be. And it appears Be = Bc by default.
> > > >
> > > > R3(config-pmap-c)#shape ?
> > > > average configure token bucket: CIR (bps) [Bc (bits) [Be
> > > > (bits)]], send out Bc only per interval
> > > > peak configure token bucket: CIR (bps) [Bc (bits) [Be
> > > > (bits)]], send out Bc+Be per interval
> > > >
> > > > So if you want a peak rate of 512000, there are multiple things you
> can
> > > > configure since you are sending Bc+Be every interval. In fact you
> can:
> > > >
> > > > 1) set peak to 512000, Bc to 5120, Be of 0
> > > > 2) set peak to 384000, Bc to 3840, Be to 1280
> > > > 3) set peak to 256000, Bc to 2560, Be to 2560
> > > >
> > > > All of these (and many more combinations) set target rate to 512000.
> > > >
> > > > So if you are not asked to specify Bc or Be and can use any values
> for
> > > > them, there are many correct answers :)
> > > >
> > > >
> > > > On Sat, Nov 22, 2008 at 10:48 AM, Hobbs <deadheadblues@gmail.com>
> > wrote:
> > > >
> > > >> I have noticed that too. When you configure shape peak, your target
> > rate
> > > >> is doubled. In you example it is 1024000bps, but nowhere did you
> > > configure
> > > >> that. I don't really understand why that is...anybody? I have tested
> > in
> > > my
> > > >> lab with shape peak 128000. It configures target rate to 256000, and
> I
> > > am
> > > >> able to push about ~240 traffic (not exactly 256 for some reason)
> > > through
> > > >> the interface.
> > > >>
> > > >>
> > > >> On Sat, Nov 22, 2008 at 6:00 AM, Huan Pham <pnhuan@yahoo.com>
> wrote:
> > > >>
> > > >>> Hi,
> > > >>>
> > > >>> I posted a similar question few months ago, and I got a very good
> > > answer
> > > >>> from Narbik. I also believe his answer is right.
> > > >>>
> > > >>> http://www.groupstudy.com/archives/ccielab/200806/msg01899.html
> > > >>>
> > > >>> However, today, I came accross an example in DOC CD, which left me
> > > >>> wondering, whether DOC CD example is wrong or not. I did come
> accross
> > > few
> > > >>> wrong example in the Doc CD before, and I believe this one is
> another
> > > one.
> > > >>>
> > > >>> Really need your opinion on this, to clear things up.
> > > >>>
> > > >>> Here's the link to the DOC CD:
> > > >>>
> > > >>>
> > > >>>
> > >
> >
> http://www.cisco.com/en/US/docs/ios/qos/command/reference/qos_s1.html#wp1014690
> > > >>>
> > > >>> shape
> > > >>>
> > > >>> To specify average or peak rate traffic shaping, use the shape
> > command
> > > in
> > > >>> class-map configuration mode. To remove traffic shaping, use the no
> > > form of
> > > >>> this command.
> > > >>>
> > > >>> shape {average | peak} cir [bc] [be]
> > > >>>
> > > >>> =================================================================
> > > >>>
> > > >>> The following example uses peak rate shaping to ensure a bandwidth
> of
> > > 300
> > > >>> kbps but allow throughput up to 512 kbps if enough bandwidth is
> > > available on
> > > >>> the interface:
> > > >>>
> > > >>> bandwidth 300
> > > >>> shape peak 512000
> > > >>>
> > > >>> =================================================================
> > > >>>
> > > >>>
> > > >>> In my opinion, this configuration will give a peak rate of 1024K,
> > > instead
> > > >>> of 512K.
> > > >>>
> > > >>> here's the config, and what the show policy interface output:
> > > >>>
> > > >>>
> > > >>> Rack1R1#
> > > >>> class-map match-all WWW
> > > >>> match protocol http
> > > >>>
> > > >>> policy-map SHAPE
> > > >>> class WWW
> > > >>> bandwidth 300
> > > >>> shape peak 512000
> > > >>>
> > > >>> interface Serial0/0
> > > >>> service-policy output SHAPE
> > > >>>
> > > >>> Rack1R1#sh policy-map interface
> > > >>> Serial0/0
> > > >>> Service-policy output: SHAPE
> > > >>> Class-map: WWW (match-all)
> > > >>> 0 packets, 0 bytes
> > > >>> 5 minute offered rate 0 bps, drop rate 0 bps
> > > >>> Match: protocol http
> > > >>> Queueing
> > > >>> Output Queue: Conversation 265
> > > >>> Bandwidth 300 (kbps)Max Threshold 64 (packets)
> > > >>> (pkts matched/bytes matched) 0/0
> > > >>> (depth/total drops/no-buffer drops) 0/0/0
> > > >>> 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)
> > > >>> 1 packets, 13 bytes
> > > >>> 5 minute offered rate 0 bps, drop rate 0 bps
> > > >>> Match: any
> > > >>>
> > > >>>
> > > >>> I think the solution should be, following. Any opinion please?
> > > >>>
> > > >>> bandwidth 300
> > > >>> shape peak 300000 37500 26500
> > > >>>
> > > >>> Rack1R1#show policy-map interface
> > > >>> Serial0/0
> > > >>> Service-policy output: SHAPE
> > > >>> Class-map: WWW (match-all)
> > > >>> 0 packets, 0 bytes
> > > >>> 5 minute offered rate 0 bps, drop rate 0 bps
> > > >>> Match: protocol http
> > > >>> Queueing
> > > >>> Output Queue: Conversation 265
> > > >>> Bandwidth 300 (kbps)Max Threshold 64 (packets)
> > > >>> (pkts matched/bytes matched) 0/0
> > > >>> (depth/total drops/no-buffer drops) 0/0/0
> > > >>> Traffic Shaping
> > > >>> Target/Average Byte Sustain Excess Interval
> > > Increment
> > > >>> Rate Limit bits/int bits/int (ms)
> > (bytes)
> > > >>> 512000/300000 8000 37500 26500 125
> 8000
> > > >>> Adapt Queue Packets Bytes Packets Bytes
> > Shaping
> > > >>> Active Depth Delayed Delayed
> > Active
> > > >>> - 0 0 0 0 0 no
> > > >>> Class-map: class-default (match-any)
> > > >>> 293 packets, 64409 bytes
> > > >>> 5 minute offered rate 0 bps, drop rate 0 bps
> > > >>> Match: any
> > > >>>
> > > >>>
> > > >>> Blogs and organic groups at http://www.ccie.net
> > > >>>
> > > >>>
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-- Narbik Kocharians CCSI#30832, CCIE# 12410 (R&S, SP, Security) www.MicronicsTraining www.Net-Workbooks.com Sr. Technical InstructorBlogs and organic groups at http://www.ccie.net
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