From: MMoniz (ccie2002@tampabay.rr.com)
Date: Sun May 09 2004 - 23:13:45 GMT-3
Well as I said..QOS is not my strongest area...
But I think the first option will not invoke shaping parameters until the BW is reached or carrier becns are received, of course if it exceeds your CIR it is very possible traffic will be dropped. This will allow the PVC to use whatever is available until the carrier starts dropping your traffic. Not good for time sensitive type traffic but for fire and forget it is good.
The second option will start to invoke shaping parameters at 64 k if it is reached.
This statement from the QOS doc is what I am trying to explain.
Frame Relay Adaptability to Congestion Example
This example does not restrict flow across a Frame Relay subinterface that has been layered onto a single data-link connection identifier (DLCI). However, in the presence of BECN bits from the network, the flow is throttled back to the committed information rate (CIR). The access rate of the interface is assumed to be 1544 kbps, and the CIR is 64 kbps.
interface serial 2
traffic-shape rate 1544000
traffic-shape adaptive 64000
traffic-shape fecn-adapt
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Kenneth Wygand
Sent: Sunday, May 09, 2004 9:16 PM
To: MMoniz; ccielab@groupstudy.com
Subject: RE: Shaping to Peak?
Mike,
Thanks for your input. Let's use your case for example. What is the _functional_ (or technical) difference between the way these two options will shape?
OPTION 1:
policy-map POLICE
class class-default
shape average 1536000
OPTION 2:
policy-map POLICE
class class-default
shape peak 64000 6400 147200
Thanks!
Ken
-----Original Message-----
From: MMoniz [mailto:ccie2002@tampabay.rr.com]
Sent: Sun 5/9/2004 8:18 PM
To: Kenneth Wygand; ccielab@groupstudy.com
Cc:
Subject: RE: Shaping to Peak?
Kenneth, the only reason I can think of is that a lot of carriers never enforce CIR!!
For instance, I have had circuits that were TI access but suppose to be like 256 CIR. By shaping to
the max T1 you still have some control of throttling if congestion occurs.
And at many times the traffic rate was well above the CIR but didn't get throttled because we were shaping to
much higher. It was only degraded when the carrier was oversubscribed or degraded.
Does that make sense? Kind of hard to explain
mike
BTW...QOS is one of my weakest subjects as is with lot's of other people.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Kenneth Wygand
Sent: Sunday, May 09, 2004 7:58 PM
To: ccielab@groupstudy.com
Subject: Shaping to Peak?
Hey everyone,
I'm really trying to understand all the options for QoS and I'm currently looking at CB Shaping. Why would one want to shape to a _peak_ instead of shaping to an _average_? I understand that shaping to a _peak_ will try to send Bc + Be bits during every Tc, but doesn't that defeat the whole purpose of shaping? Why not just shape to an _average_ but just make the Bc the total combined value of the Bc and Be values used when shaping to a _peak_, and not configure a Be?
Am I missing something?
TIA,
Ken
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