Re: LLQ- help

Oh, I understand it very well... This has *nothing* to do with burst,
as I said hours ago... :-) It has something to do when a strict
scheduler is in effect. It's in effect when software queueing is in
effect and is in effect when lower layer (for the lack of better term
- TX, parent shaper) signal they are congested (TX) or they exist
(shaper).

Now, your message I'm responding to clearly shows you really
misunderstand how CBWFQ works. There is no policer there. Conditional
policer exists only in the LLQ. Unfortunately, I'm off to watch The
Hobbit now, so I'll have to explain better in couple of hours.

PRIORITY keyword does not create a "PRIORITY QUEUE". It creates LLQ,
which I downright * refuse* call by the term used in IOS for something
else.

If you're curious. Create LLQ with 2 Mb/s priority. Send 10 Mb/s of
the traffic that matches, but *no* other traffic. Ensure that you're
not oversubscribing the outgoing interface. What will happen?

--
Marko Milivojevic - CCIE #18427 (SP R&S)
Senior CCIE Instructor - IPexpert
On Mon, Dec 17, 2012 at 9:03 PM, Paul Negron <negron.paul_at_gmail.com> wrote:
> Marko,
>
> There are 2 distinct things in play for LLQ.
>
> 1) CBWFQ scheduler- This operates exactly the way you have been stating the entire time. Congestion must be in effect for this scheduler to be operating effectively.
>
> 2) The priority Class- I think you are very mistaken about this part of LLQ. The fact that you did not understand the "Burst" proves this. Not that this is a bad thing. SO what if you did not know. Does not mean I think less of you.;-)
>
> You keep speaking about LLQ from only one of the above perspectives.
>
> I understand the multiple input interfaces deal. I was not testing the Queuing, that is very straight forward.
>
> I was testing the Policer in the Priority Class. Ya know the part that makes LLQ different from CBWFQ. You are speaking as if they behave the same when they don't.
>
> I think I see where we MAY be speaking past each other but let me clarify. I was making a point so EVERYONE would understand how the Priority Q works which is very different then what MOST people think. The statement from the point I was referencing was about the "PRIORITY" keyword, which means it is participating as a Priority Queue.
>
> Paul
>
> Paul Negron
> CCIE# 14856
> negron.paul_at_gmail.com
> 303-725-8162
>
>
>
> On Dec 17, 2012, at 11:33 PM, Marko Milivojevic <markom_at_ipexpert.com> wrote:
>
>> And mind you :-). I was not the one who talked about flows. I talked
>> about different interfaces or classes in the same policies. Two flows
>> in the same queue coming from the same input interface be it 1 or 19
>> phones is still 1 input 1 output. To see the queueing, you need
>> multiple input interfaces. Think of a Y.
>>
>> --
>> Marko Milivojevic - CCIE #18427 (SP R&S)
>> Senior CCIE Instructor - IPexpert
>>
>> On Mon, Dec 17, 2012 at 8:31 PM, Marko Milivojevic <markom_at_ipexpert.com> wrote:
>>> Paul,
>>>
>>> If there was no congestion on the TX ring, there was no LLQ. TX ring
>>> congestion is what signals to IOS that software queueing needs to be
>>> engaged. Your test was flawed, sorry to say.
>>>
>>> --
>>> Marko Milivojevic - CCIE #18427 (SP R&S)
>>> Senior CCIE Instructor - IPexpert
>>>
>>> On Mon, Dec 17, 2012 at 8:25 PM, Paul Negron <negron.paul_at_gmail.com> wrote:
>>>> I have tested it precisely!
>>>>
>>>> I put Voice traffic into the Priority Class and left the burst to default.
>>>>
>>>> I placed enough voice calls to equal the amount of traffic I used with the
>>>> "priority" command (4 calls at 32K each/NO VAD enabled). ALL traffic passed
>>>> and was not rejected. I placed a 5th call and it also went through with no
>>>> problem because it did not exceed the burst rate parameter (Voice is not
>>>> bursty). The second I placed another call, ALL of the Voice flows were
>>>> negatively impacted. The priority class began dropping traffic! It reacted
>>>> as if it was receiving burst traffic that exceeded what it would allow.
>>>>
>>>> When I extended the Burst parameter, ALL of the Voice call issues cleared
>>>> up.
>>>>
>>>> There was NO congestion on the transmit ring at ANY time during this test.
>>>>
>>>>
>>>> I also performed the same test with Live Video but the results were
>>>> devastating due to the extreme Bursty nature of the traffic I was using. I
>>>> needed to extend the  "BURST" parameter extensively due  to it's extreme
>>>> restrictive default.
>>>>
>>>> This is why some people misspeak and say that the Priority class is a
>>>> maximum value. It's true in that it binds the high end bandwidth but it does
>>>> ALLOW you to burst and squeeze a little bit more by default. It's just
>>>> REALLY restrictive. It does not enforce the 1 to 2 second recommendation.
>>>>
>>>> I still disagree with your example of where you " MAY SEE" queueing of
>>>> packets since I have NOT been able to prove it to this point. I did not ask
>>>> you to show me the packets to be confrontational or argumentative. I
>>>> actually thought I was going to learn something in this conversation about
>>>> how the Priority Queue actually buffers packets. I don't know what command
>>>> you used to verify this.
>>>>
>>>> This is why I am NOT confused about how LLQ works. I understood what the
>>>> BURST parameter actually does. I am NOT guessing.
>>>>
>>>> Policing will impose its constraint weather you are congested on the TX ring
>>>> or NOT. Same goes for Shaping!
>>>>
>>>> Paul
>>>>
>>>> Paul Negron
>>>> CCIE# 14856
>>>> negron.paul_at_gmail.com
>>>>
>>>>
>>>>
>>>> On Dec 17, 2012, at 10:19 PM, Marko Milivojevic <markom_at_ipexpert.com> wrote:
>>>>
>>>> On Mon, Dec 17, 2012 at 7:11 PM, Marko Milivojevic <markom_at_ipexpert.com>
>>>> wrote:
>>>>
>>>>
>>>> Yeah, I've seen that in the command reference as well. It's not
>>>> exactly well documented what it does.
>>>>
>>>>
>>>> What I suspect though (and this is purely speculation) is that it
>>>> allows the traffic to burst for the specified time when the LLQ is
>>>> engaged, which means when TX ring (or other choke point, i.e. shaper
>>>> in the parent class) trigger a congestion. Since there's no LLQ when
>>>> there's no congestion, I don't see how this parameter is at all
>>>> relevant when LLQ is not active. That's the thing with your statement
>>>> about 30 seconds that I mostly disagree with.
>>>>
>>>> --
>>>> Marko Milivojevic - CCIE #18427 (SP R&S)
>>>> Senior CCIE Instructor - IPexpert
Blogs and organic groups at http://www.ccie.net