From: Ahmed Mustafa (ahmed.mustafa@sbcglobal.net)
Date: Wed Feb 18 2004 - 22:37:54 GMT-3
Brian,
Good explanation. It makes sense now.
----- Original Message -----
From: "Brian McGahan" <bmcgahan@internetworkexpert.com>
To: "'Yasser Aly'" <blackyeyes00@hotmail.com>; <ccie2b@hotmail.com>;
<ccielab@groupstudy.com>
Sent: Wednesday, February 18, 2004 6:43 AM
Subject: RE: Limiting ICMP using CAR
> > >So, 128,000 kbps dvided by 8 = 16,000 = bits per interval, Tc. To
allow
> > >for a burst of 1/4 of this rate, divide by 4. 16,000 / 4 = 4000.
>
> Yes and no. The interval is determined by what you configure. Your
> target rate is 128000, which is entered in bits per second. The burst
> committed value, which comes next, is in bytes per interval. Since it is
> specified that the burst should be a quarter of the target, the rate is
> (128000/8)/4 = 4000.
>
> The reason that the Be is 4000 is that there is no excess burst.
> When Be = Bc in CAR, there is no burst. This is different from GTS and
FRTS
> where the configured Be is above Bc. In CAR if you set Bc to 4000 and Be
to
> 8000, it means your excess burst is actually 4000.
>
>
> HTH,
>
> Brian McGahan, CCIE #8593
> bmcgahan@internetworkexpert.com
>
> Internetwork Expert, Inc.
> http://www.InternetworkExpert.com
> Toll Free: 877-224-8987 x 705
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>
>
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> > Yasser Aly
> > Sent: Tuesday, February 17, 2004 7:15 PM
> > To: ccie2b@hotmail.com; ccielab@groupstudy.com
> > Subject: RE: Limiting ICMP using CAR
> >
> > Hi Packet Man,
> >
> > Bc and Be are configured in Bytes not bits. I am not sure about
whether
> > it
> > is per Tc or not.
> >
> > Needs clarification.
> >
> > Regards,
> > Yasser
> >
> > >From: "Packet Man" <ccie2b@hotmail.com>
> > >To: blackyeyes00@hotmail.com, ccielab@groupstudy.com
> > >Subject: RE: Limiting ICMP using CAR
> > >Date: Tue, 17 Feb 2004 18:27:11 -0500
> > >
> > >Yasser,
> > >
> > >I think the issue you might be having is due to the different units
used
> > >for the different parameters. Remember that the 1st parameter, cir, is
> > in
> > >bits per SECONDS while the Bc and Be are in bits per Tc which is 1/8
of
> > a
> > >second.
> > >
> > >So, 128,000 kbps dvided by 8 = 16,000 = bits per interval, Tc. To
allow
> > >for a burst of 1/4 of this rate, divide by 4. 16,000 / 4 = 4000.
> > >
> > >Now, given the requirements you stated, I think the answer that was
> > >provided is wrong. I think it should be
> > > CIR Bc Be
> > >rate-limit output access-group 100 128000 16000 4000 conform-action
> > >transmit exceed-action drop
> > >
> > >Hopefully, if I'm mistaken, someone will immediately say so and point
out
> > >my mistake. (It wouldn't be the 1st time)
> > >
> > >HTH
> > >
> > >
> > >>From: "Yasser Aly" <blackyeyes00@hotmail.com>
> > >>Reply-To: "Yasser Aly" <blackyeyes00@hotmail.com>
> > >>To: ccielab@groupstudy.com
> > >>Subject: Limiting ICMP using CAR
> > >>Date: Tue, 17 Feb 2004 18:07:34 -0500
> > >>
> > >>Hi group,
> > >>
> > >> The task is as follows: Configure E0/0 such that ICMP traffic is
> > limited
> > >>to 128Kbps.
> > >>Allow for a burst of 1/4th of this rate.
> > >>
> > >>
> > >>The answer for this question was as follows:
> > >>
> > >>acess-group 101 permit icmp any any
> > >>!
> > >>interface Ethernet0/0
> > >>rate-limit output access-group 100 128000 4000 4000 conform-action
> > >>transmit exceed-action drop
> > >>
> > >>I am confused why Bc and Be were set this way. Would you kindly
explain
> > >>and give more detail on general concepts used when configuring Bc and
Be
> > >>while using CAR.
> > >>
> > >>Regards,
> > >>Yasser
> > >>
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