Re: Shaping - identical Bc & Be values

Here's one although not a Cisco doc.

http://www.routeralley.com/ra/docs/qos_shaping_policing_efficiency.pdf

Also INE Vol I workbook GTS section - "If the Be value is equal to Bc, then
the excess burst is disabled." and also "By default, with legacy GTS, if
you do not specify a Be value it is equal to Bc."

And the link below and its examples state that they are limiting all output
to a specific value but list the same burst and excess burst values and
the "show traffic-shape" output also shows the Bc and Be values populated.
So if you have Bc set at 64000 and Be also set to 64000 it would seem that
this allows an excess burst of 64000 but apparently this is not the case.
Really confusing.

http://www.cisco.com/en/US/docs/ios/12_2/qos/configuration/guide/qcfgts.html

 GTS Enabled on the Interface Example

This example shows the configuration of two traffic-shaped interfaces on a
router. Ethernet interface 0 is configured to limit User Datagram Protocol
(UDP) traffic to 1 Mbps. Ethernet interface 1 is configured to limit all
output to 5 Mbps.

access-list 101 permit udp any any

interface Ethernet0

 traffic-shape group 101 1000000 125000 125000

!

interface Ethernet1

 traffic-shape rate 5000000 625000 625000

On Thu, Jun 21, 2012 at 6:04 AM, Carlos G Mendioroz <tron_at_huapi.ba.ar>wrote:

> If Be = Bc, then you don't realy have much to burst, and it may be
> considered that it is just to compensate for some clocking hicups.
> That in policing. In shaping, I just don't know what sense does it make,
> not that any lab test makes any sense :)
>
> Would you mind sharing where you read this, if you keep the reference ?
> -Carlos
>
> Matt Sherman @ 20/06/2012 21:00 -0300 dixit:
>
>> Hello,
>>
>> I was wondering if someone could clear this up for me. I've seen it
>> written that if the normal burst (Bc) and excess burst (Be) values are
>> equal, then excess
>> burst is not allowed. So in the examples below, if the Bc and Be values
>> are both 64000, does that mean there is no excess burst?
>>
>> GTS based Shaping
>>
>> Router(config-if)# traffic-shape rate 256000 64000 64000
>> Class-Based Shaping with a policy-map:
>> Router(config)# policy-map MYPOLICY
>> Router(config-pmap)# class MYMAP
>> Router(config-pmap-c)# shape 256000 64000 64000
>>
>> Thanks,
>> Matt
>>
>>
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> --
> Carlos G Mendioroz <tron_at_huapi.ba.ar> LW7 EQI Argentina

Blogs and organic groups at http://www.ccie.net
Received on Thu Jun 21 2012 - 11:09:47 ART