From: Ryan Morris (ryan@egate.net)
Date: Mon Jun 02 2008 - 15:35:53 ART
This has been a very interesting thread. Great discussion on the
different syntax, but can anyone explain the difference in behaviour
between the commands in Option 1 & 2 below (assuming we want 30 Mbps CIR
and 10 ms Tc).
Is there a difference in the end result? (Let's say we have a 100
Mbps fastE connection but we're not allowed to burst over 30 Mbps by our
service provider):
Option 1:
policy-map SHAPE
class class-default
shape average 30000000 300000
service-policy QUEUE
Option 2:
policy-map SHAPE
class class-default
shape peak 15000000 150000
service-policy QUEUE
For example, when does the algorithm consider the link congested, in order
to fire additional QoS queuing mechanisms in the nested policy map? Is it
different depending on the shaping technique used (i.e. PIR or CIR for
shape peak)?
Sample output:
Option 1:
R2(config-pmap-c)#do show policy-map int fa0/0.1
FastEthernet0/0.1
Service-policy output: SHAPE
Class-map: class-default (match-any)
0 packets, 0 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)
30000000/30000000 75000 300000 300000 10 37500
Adapt Queue Packets Bytes Packets Bytes Shaping
Active Depth Delayed Delayed Active
- 0 0 0 0 0 no
Option 2:
R2(config-pmap-c)#shape peak 15000000 150000
R2(config-pmap-c)#do show policy-map int fa0/0.1
FastEthernet0/0.1
Service-policy output: SHAPE
Class-map: class-default (match-any)
0 packets, 0 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)
30000000/15000000 37500 150000 150000 10 37500
Adapt Queue Packets Bytes Packets Bytes Shaping
Active Depth Delayed Delayed Active
- 0 0 0 0 0 no
Ryan Morris
CCIE #18953
On Mon, 2 Jun 2008, David Lonnie wrote:
> When you configure frame-relay traffic-shaping on s0/0 of your router,
> you are shaping the traffics outbound s0/0 interface.
> excess burst will be marked in DE bit.
> So,while the traffics with DE bit set are congesting.It will be discarded by
> other devices.
>
>
>
> On Mon, Jun 2, 2008 at 11:19 AM, Mark Stephanus Chandra <
> mark.chandra@gmail.com> wrote:
>
> > I have the same question with Mr Ahmed Here, How the other end determine if
> > my
> > traffic is a burst and the other end might potential drop the excess burst
> > traffic ?
> >
> >
> >
> > I Mean, when we configure in frame-relay, the frame-relay switch will send
> > DE
> > (Discard Eligible bit) right ? To mArk the traffic that it's an excess
> > burst
> > traffic and it might be drop.
> >
> >
> >
> > And now we are dealing with router to router traffic, what method that the
> > router will mark the excess so it is eligible to be discarded ?
> >
> >
> >
> >
> >
> >
> >
> > Mark Stephanus Chandra
> > IT Consultant
> >
> >
> >
> > From: ahmed badr [mailto:eng.ahmedbadr@gmail.com]
> > Sent: 31 Mei 2008 23:40
> > To: Narbik Kocharians
> > Cc: Mark Stephanus Chandra; Sadiq Yakasai; Cisco certification
> > Subject: Re: Shape Peak
> >
> >
> >
> > So, how will the other end determine if I'm sending with/without the excess
> > burst? at the end it will receive 256k (either by shape average 256000 or
> > shape peak 128000) ?
> > I'm confused!!
> >
> >
> >
> > 2008/5/31 Narbik Kocharians <narbikk@gmail.com>:
> >
> > CB-Shaping can be done in two different ways: Shape average and Shape Peak.
> >
> > Shape average limits the transmission rate to CIR, whereas, with Shape peak
> > the router can send more traffic than CIR.
> >
> > The formula is:
> >
> > Peak Rate = CIR (1+Be/Bc) and remember by default Be and the Bc are set to
> > 8k
> >
> > With Shape Peak you are allowed to burst higher than CIR but remember that
> > the
> > excess traffic has the potential of being dropped if the network is
> > congested.
> > Typically used if the network has more bandwidth available and the app that
> > is
> > being used can handle packet loss.
> >
> >
> >
> > On Sat, May 31, 2008 at 8:04 AM, ahmed badr <eng.ahmedbadr@gmail.com>
> > wrote:
> >
> > yes Mark, this is why I ask. unless there is a reason for that, why then
> > cisco produced the "shape peak" command if I can get the same result with
> > "shape average" and be=0 !!!
> >
> > 2008/5/31 Mark Stephanus Chandra <mark.chandra@gmail.com>:
> >
> >
> > > Hi All,
> > >
> > > Just reading you guys e-mail and suddenly just come in my mind, so anyway
> > > what the peak for then ? Is there any different treat between burst
> > traffic
> > > and commited traffic ? Just like when we configure frame relay, frame
> > relay
> > > have different treat with burst traffic, burst traffic can might be get
> > DE
> > > bit right ?
> > >
> > > Mark Stephanus Chandra
> > > IT Consultant
> > >
> > > -----Original Message-----
> > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> > > Sadiq Yakasai
> > > Sent: 31 Mei 2008 21:22
> > > To: ahmed badr
> > > Cc: Cisco certification
> > > Subject: Re: Shape Peak
> > >
> > > Hi Ahmed,
> > >
> > > Yes, you get the same data rate in this scenario because Be=0 in the
> > first
> > > case anyway.
> > >
> > > Sadiq
> > >
> > >
> > > _______________________________________________________________________
> > > Subscription information may be found at:
> > > http://www.groupstudy.com/list/CCIELab.html
> >
> >
> > _______________________________________________________________________
> > Subscription information may be found at:
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> >
> >
> >
> >
> >
> >
> >
> >
> >
> > --
> > Narbik Kocharians
> > CCSI#30832, CCIE# 12410 (R&S, SP, Security)
> > www.Net-Workbooks.com
> > Sr. Technical Instructor
> >
> >
> > _______________________________________________________________________
> > Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
>
>
> _______________________________________________________________________
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