Re: QoS interpretation

Thanks Roy ...what always gets me confused is the wording... here " the
maximum " but i think the line in bold makes it very clear
but during my study i dont see any wording for the peak..its always use peak
sometimes use target rate vs avg rate

 ".... BB2 will only allow R5 to send traffic across this link at a
maximum of 2.5mpbs.
  ----- Original Message -----
  From: Roy Waterman
  To: Mohamed El Henawy
  Cc: Nick ; Gabriel ; Cisco certification
  Sent: Saturday, April 25, 2009 4:25 PM
  Subject: Re: QoS interpretation

  Hi Mohammed
  This comes to knowing the difference between shape peak & shape average.
  As per the QoS command ref for shape [average|[peak]
  -----------

  Peak rate shaping allows the router to burst higher than average rate
shaping. However, using peak rate shaping, the traffic sent above the CIR (the
delta) could be dropped if the network becomes congested.

  If your network has additional bandwidth available (over the provisioned
CIR) and the application or class can tolerate occasional packet loss, that
extra bandwidth can be exploited through the use of peak rate shaping.
However, there may be occasional packet drops when network congestion occurs.
If the traffic being sent to the network must strictly conform to the
configured network provisioned CIR, then you should use average traffic
shaping.

  I think the clear answer here is shape average

  Regards

  Roy

  2009/4/25 Mohamed El Henawy <m.henawy_at_link.net>

    so this should be shape avg or shape peak ?

    ----- Original Message ----- From: "Nick" <ccieaz_at_googlemail.com>
    To: "Gabriel" <mail.to.gabriel_at_gmail.com>
    Cc: "Cisco certification" <ccielab_at_groupstudy.com>
    Sent: Wednesday, April 15, 2009 4:49 AM
    Subject: Re: QoS interpretation

      Thank you for you help. I see why shaping is used in this question now.
:)

      Nick

      2009/4/15 Gabriel <mail.to.gabriel_at_gmail.com>

        You police as the provider, you shape as the customer. In these
        examples, you are the customer and the owner of BBn is the provider,
        so he is policing and you should shape.

        If you think about it, it makes sense this way: if you're the
        provider, you don't care what happens to the customer's excess
        traffic: you promised the customer X mbps and that's all he gets. If
        you're the customer with a policed pipe, you want to do the best you
        can to make good use of that X mbps for your most important traffic,
        so you shape to fit the rate that's being policed by the provider.

        -Gabriel

        On Tue, Apr 14, 2009 at 6:24 PM, Nick <ccieaz_at_googlemail.com> wrote:
> Hi all,
>
> I still have trouble sometimes with QoS question interpretation.
>
> Take this example from IE lab 18
>
> ".... BB2 will only allow R5 to send traffic across this link at a
        maximum
> of 2.5mpbs. BB3 will only allow R5 to send traffic into its network
at > a
> maximum rate of 3mpbs"
>
> How should I interpret this?
>
> I think that you could do this with shaping, policing or bandwidth
> statement. But which is best and why?
>
> Any tips would be great.
>
> (SG uses shaping)
>
> Thanks
>
> Nick
>
>
> Blogs and organic groups at http://www.ccie.net
>
>
Received on Sat Apr 25 2009 - 16:56:13 ART