From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Wed Feb 18 2004 - 11:43:09 GMT-3
> >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
Outside US: 775-826-4344 x 705
> -----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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