Re: LLQ- help (with elephants)

From: Marko Milivojevic <markom_at_ipexpert.com>
Date: Wed, 19 Dec 2012 16:28:45 -0800

Yeah... WOW indeed... I'll just leave it at that.

I'll also remember that proving you have no idea what you're talking
about and making my point, at least 5 times during this thread is
"making love to myself and not getting to the point".

--
Marko Milivojevic - CCIE #18427 (SP R&S)
Senior CCIE Instructor - IPexpert
On Wed, Dec 19, 2012 at 4:23 PM, Paul Negron <negron.paul_at_gmail.com> wrote:
> I meant it too man when I said Merry Christmas! I don't hate you. You just
> seem to want to belittle people WITHOUT the direct insults.
>
> Making Love to yourself was not calling you a name either. That was my way
> of saying b&GET TO THE POINT!!! Forget about the theatrics. No one wants to
> hear that on here.
>
> You take yourself way too seriously!!!
>
> I apologize if I hurt your feelings!
>
> WOW!!
>
> Paul Negron
> CCIE# 14856
> negron.paul_at_gmail.com
> 303-725-8162
>
>
>
> On Dec 19, 2012, at 7:09 PM, Marko Milivojevic <markom_at_ipexpert.com> wrote:
>
> Get off you? It's you who keep bringing this matter up...(and call
> names - which I will not resort to, no matter how deserved it is; what
> you resorted to in
> this thread is downright disgraceful and shameful). I
> even wished you Merry Christmas when you said vacation earlier today
> in a unicast message, but you keep bringing the matter up. Lab it up
> now, or just publicly send the e-mail you sent me yesterday. I find it
> good etiquette not to repost unicast messages...
>
> I trust my own notes dude.
>
>
> I don't. Noone should, as we've never seen the test. Credibility lost
> is not recovered by saying "it's my notes" and "my buddy Wendell has
> them, but not the configs".
>
> I will always do what's in my power to prevent students from learning
> the wrong things. That means when I'm wrong (and I have been many
> times), I will publicly say so. It only works to improve me as an
> engineer and show everyone how we can all make mistakes. I suppose we
> are not all the same. Really, shame on you.
>
>
> -Marko.
>
> On Wed, Dec 19, 2012 at 4:02 PM, Paul Negron <negron.paul_at_gmail.com> wrote:
>
> I was going to lab it up when I get back from Vacation with My 6 Kids and
> Beautiful wife Bro!
>
>
> Get off me!!!
>
> I trust my own notes dude.
>
> Paul
>
> Paul Negron
> CCIE# 14856
> negron.paul_at_gmail.com
> 303-725-8162
>
>
>
> On Dec 19, 2012, at 6:57 PM, Paul Negron <negron.paul_at_gmail.com> wrote:
>
> I'm sorry. I lost you in you making love to yourself.
>
> What are you saying?
>
> I am incorrect about the BURST?
>
>
> Paul
> Paul Negron
> CCIE# 14856
> negron.paul_at_gmail.com
> 303-725-8162
>
>
>
> On Dec 19, 2012, at 6:52 PM, Marko Milivojevic <markom_at_ipexpert.com> wrote:
>
> You are just not giving up, are you? You are using cyclic logic to
> explain what BURST (to use your spelling) does, still not explaining
> it.
>
> If the policer works as a single-rate two-color policer, then BURST is
> used to calculate the measurement interval. However, read one of my
> previous messages where I offered two explanrtions for the burst: one
> according to what Cisco documentation says, which is *decidedly* in
> contrast to what YOU claim, but never show. Another one was the
> explanation that's in-line with your CLAIMS, but in contrast to Cisco
> documentation. Which one is it then? Cisco or you? If it's you,
> where's proof? If it's Cisco, then you're wrong all along...
>
> So, dear Paul - don't go back to a single statement I made and keep
> putting it *completely* out of contest only because you cannot make
> any reasonable argument and have lost all credibility in this
> discussion. Go, get some gear and lab it up, as both Carlos and I have
> done... or are you just talk and no walk?
>
> --
> Marko Milivojevic - CCIE #18427 (SP R&S)
>
>
> On Wed, Dec 19, 2012 at 3:43 PM, Paul Negron <negron.paul_at_gmail.com> wrote:
>
> ALL,
>
> I spoke with my friend Wendell and he still had notes on my test. No
> configsb&sorry:(
>
> The one thing I forgot was that the link was 128K that I was testing on at
> the time. Very similar to the the 128K test that Carlos accidentally forced.
>
> Therefore, when I placed 4 calls that tootled approx 112K of the Pipe. All
> worked well. The 5th call went through fine cause it was not enough to
> congest the link. The 6th call had to have had congested the link which
> kicked in the BURST parameter set in the Priority Queue and traffic dropped
> traffic out of the VOICE CLASS.
>
> WHen I used Video, I used enough Video traffic to barely congest the link
> but the BURST was much greater to cause more drops.
>
> I also have in my notes that the POLICE action worked very similar to a
> Single Rate 2 Color Policer. '
>
> The conclusion was that the Priority Class Burst Parameter will drop traffic
> only when the link is congested, even if it's by a little depending on the
> traffic.
>
> This is how the BURST parameter works.
>
> I believe Mr Neiberger said this exact same thing in a previous post. (Good
> Job Neiberger).
>
> Marko was correct about the congestion but I never argued about the CBWFQ
> portion of this. Just the Priority Queue behavior with the BURST parameter.
> It's just that the BURST parameter ONLY kicks in when there is congestion on
> the physical interface. I believe Carlos also agrees with this but I will
> let him speak for himself. Not sure if Marko agrees since he admitted he did
> not know how the BURST worked. (Not that there is anything wrong with that)
> :-)
>
>
> Paul
>
>
> Paul Negron
> CCIE# 14856
> negron.paul_at_gmail.com
> 303-725-8162
>
>
>
> On Dec 19, 2012, at 7:28 AM, Carlos G Mendioroz <tron_at_huapi.ba.ar> wrote:
>
> Oh my.
> I found why the policer was dropping in FR: the serial was clocked at 128K
> on the other side :(
>
> (This was cloaked by SNMP showing TX at 200k for as long as I tested, w/o
> the policy... this is indeed a heads up on SNMP metering for me).
>
> Sorry about that.
>
> On the other hand, I would like to share an example on one of the reasons we
> need bursting:
>
> Assume we have someone that has to send some elephants through a path that
> crosses a river with a bridge. The brisge has a guard that is told not to
> let more than 3 elephants per minute through, and just kill any violating
> elephants that may arrive at bridge entrance.
>
> Knowing the bridge policy, the herd owner ask you to be carefull not to send
> more than 3 epm. (elephants per minute).
>
> So you start your clock and send at times:
> 0'10
> 0'30
> 0'50
> 1'00
> 1'15
> 1'30
> 2'12
> 2'40
> 2'55
>
> Right ? No minute had more than 3. All elephants walk preciselly at speed of
> light :) and arrive w/o jitter at the bridge, but the gatekeeper's watch is
> not synchronized, so let's add 15 seconds and see:
>
> 0'25
> 0'45
> 1'05
> 1'15
> 1'30
> *1'45* Kill it, 4th in a minute!
> 2'27
> 2'55
> 3'10
>
>
> What went wrong ? Well, metering. That's one of the reasons we need
> bursting.
>
> Hope nobody gets under one elephant foot :)
>
> -Carlos
> P.S.
> No animal was hurt in this test!
>
>
>
>
> Carlos G Mendioroz @ 19/12/2012 06:50 -0300 dixit:
>
> Paul,
> I would kindly ask you to apply some policing on words like CRAP. Those
> raise the emotions w/o adding any technical data...
>
> Now, it would be great if we agree on what we say. Congestion is a not
> very precise word. It might be that your are dropping packets, that you
> have some packets backlog (queue), or that your processor is running at
> top speed. In cisco's queue management, it's usually used to denote that
> one interface's TX ring is full, so the router can not just FIFO packets
> at interrupt time and has to "engage" software queueing.
>
> Marko, I and a lot of people at cisco (e.g. Tim Szigeti) kind of konw
> that CBWFQ or LLQ vanish when not congested, for good reason.
> Well, not if you have "police" commands. Those work always.
>
> So one or the arguments (main one ?) is that the "priority xx yy" is not
> going to produce drops unless somehoy you force LLQ to engage.
>
> It seems that there is some other way that cisco implements that also
> takes the "priority xx yy" into consideration that I stumbled on, while
> trying to prove this with a test.
>
> Now, real phone stream is not golden test data. Cisco has special images
> to generate test data and if you have a programmer side, you can do that
> too, or use one of the many tools to do CBR, or some VBR.
> As long as you send below your output TX rate, you should not congest,
> and testing with low values of priority should be enough to see test
> results.
>
> BTW, the reason for the implicit policer is fairness. The priority queue
> is served always first, and there is no scheduler check for that. That's
> why you need to prevent much traffic from entering the queue or else it
> will starve others. "Queue" here is a control mechanism, it cisco says
> it has not packet count limit.
>
> -Carlos
>
>
> Paul Negron @ 19/12/2012 01:30 -0300 dixit:
>
> Guys,
>
> The reason why we are going through this is because of a statement I
> said a while back in the thread that Marko is disagreeing with.
>
> I tested this crap with REAL Voice packets from a real phone from a
> multiple real FXS ports.
> Not your crappy UDP tests that may not set up real BURST behavior like
> real Video.
>
> I remember trying to prove that the Priority Queue would NOT drop
> packets if I sent more Call traffic through it in the event that there
> was NO congestion. Very similar to what Marko is saying. To my surprise
> I saw the Priority Queue actually drop traffic when I had placed 2 more
> calls than the "Priority" command was configured for.
>
> Marko said I had done an" Invalid test" which I felt was very Cocky on
> his part especially when he could not recall how the Burst command
> actually worked. It's kinda like saying someone else is wrong before you
> know ALL the facets involved. He could be right but I guarantee he is
> NOT performing the same test with REAL traffic from REAL devices. He is
> NOT listening he is just trying to win an argument. WHATEVER!!
>
> The reason why the Priority Queue introduced the policer was to
> protect the Priority Class from using too much traffic in the event that
> other classes were not using their share. Now this was when QOS was
> first introduced to the code and I was testing on Frame-Relay links so
> it COULD have been flawed side it looked like Carlos's test showed but I
> am NOT completely sure since I am getting different results from
> different people now (like Carlos and Marko). I remember what I saw
> cause I repeated the same test with REAL Video Traffic and got similar
> results. The priority Queue would drop traffic prior to congesting the
> link due to very high burst in a very small period of time. The behavior
> was almost like CAR not Class Based Policing.
>
> I may be getting old and soft in the brain but I remember that test. It
> was the Original QOS lab that SKYLINE would run for QOS back in 2002 I
> think. One 2600 with FXS ports connected to another 2600 with FXS ports.
> We would set up an HTTP server and create Video Flows from Cisco IPTV to
> congest the link.
>
> I put in a call to Wendell Odem to refresh my memory since we set up
> that lab together.
>
> I almost hope he agrees with Marko cause it would make more sense that
> way since it would behave most like a pure Queuing mechanism. John
> Neiberger also added very accurate insight that agreed with Marko but I
> KNOW he is listening to the whole conversation with an unbiased eye.
> (thanks man). This discussion is waking up my brain on this subject and
> I actually enjoy the dialogue.
>
>
> Paul Negron
> CCIE# 14856
> negron.paul_at_gmail.com <mailto:negron.paul_at_gmail.com>
>
>
>
> On Dec 18, 2012, at 6:46 PM, Marko Milivojevic <markom_at_ipexpert.com
> <mailto:markom_at_ipexpert.com>> wrote:
>
> That's exactly my point. We don't (you talked about single-rate
> policer, not me, btw.). This is what the description of the command
> says:
>
> "(Optional) Burst size in bytes. The burst size configures the network
> to accommodate temporary bursts of traffic. The default burst value,
> which is computed as 200 milliseconds of traffic at the configured
> bandwidth rate, is used when theburst argument is not specified. The
> range of the burst is from 32 to 2000000 bytes."
>
> Further down, there's an example:
>
> "Examples
>
> The following example shows how to configure PQ with a guaranteed
> bandwidth of 50 kbps and a one-time allowable burst size of 60 bytes
> for the policy map named policy1:
>
> Router(config)# policy-map policy1
> Router(config-pmap)# class voice
> Router(config-pmap-c)# priority 50 60"
>
> Now, look me in the eye and say this sounds like Bc to you? To me,
> this sounds more like a Be (which implies two rate policer. This is
> not the three color policer, as there seems to be no option to specify
> three actions, hence my comment that it sounds like be, but not even
> that, as it lacks the functionality I'd expect to see...
>
> Now, there are two possibilites:
>
> 1) Cisco documentation is wrong and this indeed specifies Bc for a
> single rate, two color policer. It would actually make sense, as it
> allows the possibility to adjust metering on transmission side to the
> metering on the receiving side (other side of the link), should they
> be mismatched. This is not an unlikely scenario and it's what you're
> saying.
>
> 2) This is indeed a temporary "excess burst", but with the implied
> "transmit" action, meaning that it can be used to create a two rate,
> two color policer. According to the documentation, this is what it is.
>
>
> --
> Marko Milivojevic - CCIE #18427 (SP R&S)
> Senior CCIE Instructor - IPexpert
>
> On Tue, Dec 18, 2012 at 3:39 PM, Narbik Kocharians <narbikk_at_gmail.com
> <mailto:narbikk_at_gmail.com>> wrote:
>
> Since when do we have a Be in single rate two color policer?
>
>
> On Tue, Dec 18, 2012 at 3:33 PM, Marko Milivojevic
> <markom_at_ipexpert.com <mailto:markom_at_ipexpert.com>>
> wrote:
>
>
> Well, let's talk about the burst parameter, because I believe we
> reached a conclusion it does not work like Bc (i.e. to determine the
> Tc). Rather it works more closely to Be, but not even that... :-)
>
> I'm not confused about it - I just can't seem to find the information
> what it does. I can *believe* what it does, but that doesn't explain
> it to me ;-)
>
> --
> Marko Milivojevic - CCIE #18427 (SP R&S)
> Senior CCIE Instructor - IPexpert
>
> On Tue, Dec 18, 2012 at 3:30 PM, Narbik Kocharians
> <narbikk_at_gmail.com <mailto:narbikk_at_gmail.com>>
> wrote:
>
> I have not, why would you say that? I am not going to participate
> in you
> said he said stuff. The burst in LLQ works the way I explained it,
> and I
> still say that, when did I say the burst does not work the way i
> mentioned?
>
> The burst in LLQ works just like the Bc in a single rate 2 color
> policer.
> NOW...whether it's behavior is that way during congestion or not it
> needs to
> be tested, I believe it works that way during congestion, but i do
> not
> have
> the testing gear to provide results, the tests shown in some of the
> examples
> are ridiculous to test the complete package, things like burst and
> playing
> with the burst value.
>
> It was you that was confused about the burst parameter and not me. Go
> back
> and read what you wrote.
>
>
> On Tue, Dec 18, 2012 at 3:15 PM, Marko Milivojevic
> <markom_at_ipexpert.com <mailto:markom_at_ipexpert.com>>
> wrote:
>
>
> Thank you for agreeing with what I was saying all along (even though
> it kind-of contradicts your previous burst statement) ;-)
>
> Now, testing LLQ is tricky and making calls is not exactly the best
> way to test it, should you intend to use it for something other than
> voice. Any throughput, queueing, performance testing is best left to
> the professional tools designed for that purpose. Human ears are
> not a
> good tool :-).
>
> For anyone with (serious) production concerns about the LLQ and a
> (serious) testing budget, I can only highly recommend Spirent
> SmartBits or TestCenter products. They are *unparalleled* to what
> you'll be able to learn about your routers and switches and their
> (lack of) performance... :-)
>
> --
> Marko Milivojevic - CCIE #18427 (SP R&S)
> Senior CCIE Instructor - IPexpert
>
> On Tue, Dec 18, 2012 at 3:09 PM, Narbik Kocharians
> <narbikk_at_gmail.com <mailto:narbikk_at_gmail.com>>
> wrote:
>
> Totally agree with what was stated in that link.
> We have to remember that PQ, CBWFQ, are all congestion management
> tool.
> but
> the best way to test LLQ is to actually make calls and test the
> quality.
>
> On Tue, Dec 18, 2012 at 2:40 PM, Joe Sanchez <marco207p_at_gmail.com
> <mailto:marco207p_at_gmail.com>>
> wrote:
>
>
> Here is a great view:
>
>
>
>
> http://www.cisco.com/en/US/docs/ios/12_0t/12_0t7/feature/guide/pqcbwfq.html#wp5329
>
>
> JS
>
> On Tue, Dec 18, 2012 at 3:28 PM, Marko Milivojevic
> <markom_at_ipexpert.com>
> wrote:
>
>
> For fun, I added another source of the traffic and lowered
> bandwidth
> on the interface to 768000 (in an attempt to actually create a
> congestion). This is by no means an exhaustive test of LLQ and
> the
> quality, but it shows a conditional policer in action.
>
> ------------------------------8<------------------------------
>
> !!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!
>
>
> !!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>
>
> !.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!
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> !!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!
>
>
> !!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!
>
>
> !!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!
>
>
> !!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!
>
>
> !!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!
>
>
> !!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!
>
>
> !!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!
>
>
> !!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>
>
> !.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!
>
>
> !!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!
>
>
> !!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!
>
>
> !!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!
>
>
> !!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!
>
>
> !!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!
>
>
> !!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!
>
>
> !!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!
>
> ------------------------------8<------------------------------
>
> If you look closely at the pattern of drops above, you will
> observe
> the regular intervals at which they appear. This *can* be an
> indicator
> of active traffic conditioner. Let's see what our policy says.
> Keep
> in
> mind that the other traffic generator is much more aggressive
> than
> the
> first (timeout 0).
>
> ------------------------------8<------------------------------
> R2#show policy-map interface Serial0/2/0 output class PRIORITY
>
> Serial0/2/0
>
> Service-policy output: LLQ
>
> queue stats for all priority classes:
>
>   queue limit 64 packets
>   (queue depth/total drops/no-buffer drops) 0/0/0
>   (pkts output/bytes output) 158281/238054624
>
> Class-map: PRIORITY (match-all)
>   344671 packets, 518385060 bytes
>   30 second offered rate 10173000 bps, drop rate 9649000 bps
>   Match: protocol icmp
>   Priority: 100 kbps, burst bytes 2500, b/w exceed drops:
> 186359
> ------------------------------8<------------------------------
>
> The problem is that this test is flawed when it comes to
> reproducing
> the real congestion, as here we also have to take into account
> that
> the traffic is arriving from the same input interface, so we have
> 1:1
> input:output mapping (again, something I mentioned very early in
> this
> thread as an important factor).
>
> I could spend even more time labbing it up for you, but I suppose
> I've
> done enough train-the-trainer for one day :-).
>
> --
> Marko Milivojevic - CCIE #18427 (SP R&S)
> Senior CCIE Instructor - IPexpert
>
> On Tue, Dec 18, 2012 at 1:16 PM, Marko Milivojevic
> <markom_at_ipexpert.com>
> wrote:
>
> On Tue, Dec 18, 2012 at 1:14 PM, Narbik Kocharians
> <narbikk_at_gmail.com>
> wrote:
>
> How did you prove that LLQ kicks in during congestion? How did
> you
> measure
> the quality of these packets?
>
>
> Well, that's not at all what I was testing, as the test was
> built
> specifically to avoid congestion to show how there's no policing
> when
> congestion does not occur. Apples and Oranges.
>
> Testing the quality of these packets would be difficult (not
> impossible) to measure using IOS-only and Voice SLA probes as
> traffic
> generators, but as I said... this was not the point here.
>
> --
> Marko Milivojevic - CCIE #18427 (SP R&S)
> Senior CCIE Instructor - IPexpert
>
>
>
> Blogs and organic groups at http://www.ccie.net
>
>
>
> _______________________________________________________________________
>
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>
>
>
>
>
>
>
>
>
>
> --
> Narbik Kocharians
> CCSI#30832, CCIE# 12410 (R&S, SP, Security)
> www.MicronicsTraining.com <http://www.MicronicsTraining.com>
> Sr. Technical Instructor
> YES! We take Cisco Learning Credits!
> A Cisco Learning Partner
>
>
>
>
>
> --
> Narbik Kocharians
> CCSI#30832, CCIE# 12410 (R&S, SP, Security)
> www.MicronicsTraining.com <http://www.MicronicsTraining.com>
> Sr. Technical Instructor
> YES! We take Cisco Learning Credits!
> A Cisco Learning Partner
>
>
>
>
>
> --
> Narbik Kocharians
> CCSI#30832, CCIE# 12410 (R&S, SP, Security)
> www.MicronicsTraining.com <http://www.MicronicsTraining.com>
> Sr. Technical Instructor
> YES! We take Cisco Learning Credits!
> A Cisco Learning Partner
>
>
>
>
> --
> Carlos G Mendioroz  <tron_at_huapi.ba.ar>  LW7 EQI  Argentina
Blogs and organic groups at http://www.ccie.net
Received on Wed Dec 19 2012 - 16:28:45 ART

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