I really like the "law enforcement official" metaphor at 40:01 "I travelled at a rate of 120mph for 30 minutes and then I travelled at a rate of 0mph for another 30 minutes..." :-D
I'm studying for CCIE and as far as the CCIE QoS resources is concerned, I can say this video is the best QoS resource available out there. It's even better than Cisco DocCD. I went through the DocCD of Cisco and I'm lost till I found this fantastic video. Special thanks for you Kavin and for your efforts. That's really a great job. Well done and keep it up.
Hi Kevin. Between the 21-22 minutes mark, you mentioned that if an incoming non IP frame has a CoS marking, and the switch has MLS QoS enabled, the switch allows the marking to be maintained. Wouldn't the switch remark the incoming marking to CoS 0 if MLS QoS is enabled, but a trust boundary is not defined?
i have a comment that i need to add , i'm working on my CCIEwirelesss, and we should have basic knowlegde about switch Qos , so i searched youtube, found your video title saying "QoS simplified..seriously!!!" i said ok this is what i'm looking for , and i start watching , and after almost 15 min , you are saying "this video consider that you have basic knowledge of Qos , and this is for CCIEvoice, " , , , what a time wasting !!!! , i think you need to rename the video title, and add an comment telling that this video for CCIEvoice, thank you
Hi Kevin great Video, just one confusion. If we have a Priority Queue and also Bandwidth shaping applied which one will take precedence ! I know that shaping takes precedence over a shared queue but what if we also have a Priority Queue applied on a port also !.
Just to make sure I understand.... If the rate is that of the line rate when using a policer, then if we used "mls qos srr-queue input bandwidth 70 30" (For example)...would the line rate be that of the queue in which the traffic would fall into? For example, if we have a 1Gbps link with a 256K + 8000 Byte policer....if the traffic would fall into queue one, would the line rate actually be ~700Mbps? Just trying to figure out how they all interact. Furthermore...does the bandwidth global command ...come before the buffer global command? I'd THINK that the buffer would only come into play if the traffic for the particular queue exceeds the allocated bandwidth?
Kevin, I the configs you use srr cos commands. In our data center and remote sites we use wrr cos commands. Is there a time when you should perfer weighted round robin over the shaped round robin command? awesome video Thanks B
You favor your dad! Thanks to your dad for passing the torch. You have helped me in understanding this field and I'm sure, thousands of others. Thanks so much!
1:41:25 Does it mean that only COS 4 frames will enter into that queue or it will allow all traffic and when it sees congestion start discarding COS 4 frames at threshold 1 ?
Thanks Kevin, that was an excellent video... Do you know what the new CCIE R&S v5 setup will be? Aren't those switches based on 3560X architectures I believe?? Is there much of a difference... On another note, I will come back and have a look what videos you have, but do you have anything good on Route Redistribution and Mutual Redistribution for R&S Labs? Thanks again, keep up the great work....
Hi Kevin, Great video! Has been very useful! I got a question about input queue: Cisco documentaton talks about "mls qos srr-queue input bandwidth weight1 weight2" where "The ratio of the weights is the ratio of the frequency in which the SRR scheduler sends packets from each queue." I'm struggling to understand its meaning. It is a kind of policer for not starving the other queue? (i.e. if I have 10 Megabits in Q2 with a ratio of 45 % - weight 4 4 - the SRR will serve 4.5 Megabits of those 10 and it will serve Q1 for its 45% and then it will come back to serve again Q2 for its 45%) ThankYou
Thanks Kevin, this is the best description I've found of the port queueing operation.A couple of questions:1. @~1:20:00 mapping QoS to Output Q. Assuming no other marked traffic (DSCP) am I correct in thinking that the example given would result in the queues never getting fully utilized (because no traffic will ever hit the any of the Qs 3rd thresholds)?2. If a packet is marked with CoS and DSCP which takes precedence when choosing which Q to go in?Finally do you have any real world examples - e.g. when might we use vlan classification rather than port classification etc.thanks again.
Hi Kevin Thanks for the video. Thumbs up to you. Question: At 1.15.39 timestamp, isn't buffer and maximum allocation is the same in terminology. Also, why we need to configure buffer and bandwidth together. Doesn't these values need to be the same correlate to function properly? Thanks.
Hi Kevin, One questions regarding the command exceed-action policed-dscp-transmit . What happens to the packets, which do not have any DSCP value stated in "map policed-dsp". Are they gonna be dropped? Keep going with producing such great training material! thanks.
Very nice video! Thanks :) One question though: why is it that, as stated in Policing an SVI (Policing Example 4), you need the nested policy-maps? I don't get it. Why can't the interface matching in the PORTS class-map just be moved to the RTP class-map?
Kevin, this is really knowledgeable but might need to go through couple of times to fully understand these complex concept, also would you mind to make a same kind of QoS on Routers as well.
Hi Kevin, Thanks for this great video. I have a question on policing command .In most of the example on cisco doc , I see "burst size" is always used as 8000 ( and that is min you can keep). For example police 24000 8000 conform-action transmit. But If its allowing 8000 bytes which is 64000 bits its already exceeding my policed rate which is 24K.
Hi Kevin, at approx 42 minutes in the video you discussed policing. police 256000 8000 exceed-action drop. you mentioned there will be 8000 byte burst and over a period of time we would have sent 256 kbps. my question is what is the definition of time. is it a second or it varies on some factor technological factors.
This is awesome video!! I love it. I have seen many videos which you show that. I have learned many knowledgy even thought i dont unterstand every single your words because Im a korean, but i still watch your video. Thank you for update new videos i learn and help me to get closer a step toward my dream job. Im gonna wait your next one!
Maybe this link will help - it does seem that the trust marking determines what branch of decision logic and eventually map the packet/frame will have applied to it. Google "Catalyst 3560 Switch Software Configuration Guide, Release 12.2(55)SE", search for "Figure 34-3"
21:40 "If the frame has a CoS value, keep it." After enabling QoS, won't all the interfaces become untrusted by default and change the CoS value to 0? Only the trust CoS would allow the frame to keep its CoS value.
Wow been looking around for an article or a video explaining QOS in simple way.. This really helps a lot I watched it multiple times. More of this please. Thank you sir! much appreciated
Hi Sir, this video is just awesome. The content is so clear and you present it in a clear and educational fashion. I've also read some of your books (CCNP track). I'm glad such quality person helped me (virtualy/remotely) learn great things. Thank you.
What more you can say about this wonderful gentleman. He is a star with immense capability to explain very hard topics in relatively simple topics. Simple but practical approach. Very nice. Thank you Kevin. Keep up your good work. We would like to see more of QOS on catalyst 3850 and what the difference between routers and switches when it comes to QOS.
Kevin - My Dad (now passed) was an old Telephony guy so I too have this voice stuff in my blood! I have read and listened to you over a couple of years now and I so appreciate you sharing your knowledge. And it’s really cool to know some of your background. GOD bless your family and you!!! Keep up the wonderful work.
WOW.. first glimmer of light in 2020 still relevant for us still running older kit in the network! Kevin just explained the dark arts of QoS in an hour and a half, something which years of frustrated reading has never helped with.. Gobsmacked you have made it and explained it so simply and efficiently.. Highly, Recommend viewing to anyone wanting to learn MLS QoS... Kevin I doff my cap from the good old UK sir!
Great Video Kevin. Where I work, we don't use QOS on any of our switches for VOIP traffic - even though it is supported. I only recently picked this up after learning about it in my CVOICE studies. I told my manager about my vision of crystal clear VOIP across our multisite international environment and have been given the all clear to 'own' the project. Nothing like a bit of self development to earn additional recognition, self safisfaction and the goal of a pay rise ;)
OMG this is simplified ver.? lol. Excellent job Kevin, really, it´s a huge topic and it´s really hard to explain well, concise and practical and you did. Thank you so much...oh God need to relax my mind, lol.
so how does all this gets combined? ... I mean, cool, understood the theory and commands and all....Great Vid, but how does all fit together. Can u do a 3 Min Vid to show all these commands at a lab env? :) Any Good books that ties all these together?
Around 36m, you discuss policing. And in the example you discuss dropping VoIP traffic over a certain bandwidth. This seems to be a very strange use case. Wouldn't you generally want to prioritize 'realtime' media traffic and only drop bulk traffic?
It's the 2nd time I watch this video from the beginning to the end...i wish there was a backgound presentaion avaliable as well so I don't have to rewind but still thank you for doing this video, you are able to explain things pretty good. Gota check your books :)
So im a college student, the last week we did some really basic theory quality of service class, and they told us: "Choose a cisco router , say why you choose it, and implement qos" After hitting my head against a wall for a week in gns3. I found this video. But as i said before my knowledge of qos is null. I find this really interesting but i lack a start point. Any advice, any specific video i could watch. Would be really appreciated. Thx, and ill watch this video when im at the lvl of it :)
Also I noticed that you didn't apply vlan-based QoS while doing the mutations, although they use some kinds of classification, would you please clarify this confusion..
Hi Kevin, that cleared up a lot of questions for me too. Thanks a lot. One quick question, in your policing sample configuration, police 256000 8000 exceed-action drop, which yields Tc=250ms! However, Tc should not be larger than 125ms, am I correct?
Kevin, your video is awesome and I come back to it over and over. Please, please clarify something for me. One vendor I am using states that the SRR bandwidth limit command does not have any effect on SRR bandwidth shape command -- shape still uses interface speed. Your video states to the contrary and indeed I can't find Cisco documentation to support the vendor's claims but I can't understand why they would go out of their way to make the point, in multiple resources. Comments? Thanks Derek
Great video! But one question remains in regards to buffers. How many bytes can a buffer hold . The best reference I could find was in a white paper that state 2M
Thanks for your quick reply. One more question, there're cos-map and dscp-map for both input and output queues to map marked frame/packets to correct queue. Since both maps are configured separately and can be mapped differently, in what condition will the switch refer to cos-map to map frame/packets? likewise, in what condition will the switch refer to dscp-map? thanks a lot!
Such a great video! Very clear, concise yet still comprehensive and excellent pace. I'll have to watch the video again to make sure this wasn't already mentioned and I missed it, but I think there was also a caveat with priority queues, in that when a queue is made a priority queue, that Queue's configured weight no longer counts towards the "total" that is used to calculate the percentage of weight for the other Queues. Keep up the good work!
Kevin, I am a CCNP and CCNP-Voice working for a Gold Partner. Your video has helped me overcome the last hurdle before complete understanding. Class maps, Policy Maps, Service Policies, Access lists vs Trust, all of these concepts are easy, but interface queues and global cos and dscp value mapping have always tripped me up. Thank you for taking the time to put this together. Much appreciated sir.
Thanks Kevin for sharing your knowledge again. Another fantastic breakdown of a technology that can get very confusing. This really helped me review a subject I haven't used for many years.
So, i've been using QoS a little bit lately at work; and this video seriously cleared up so much to me. I now understand what i'm really doing. This video could not have been any more clear.
***** Thank you! I have one quick question if you don't mind; its in regards to remarking exceeded traffic with a different DSCP marking. In the video I believe the example was remarking "46" traffic to a DSCP of "8". Why would we want to set EF traffic to a lower DSCP if it was originally 46. Given that a link is saturated; wouldn't you want to keep the traffic marked as 46 to make sure it gets out as soon as possible?
Kevin, you just covered a would be 20 hour qos session in one video, and very easy to understand, super great job. You should be one of the instructor for one of the ccie online schools like ine, ipexpert etc
Hi Kevin I really enjoyed your video on RU-vid It helped me understand better process how QoS is builded up. During that video I was making the notes and I got confused with SSR In the video 59:44 - you said that “...in the INPUT queue it has to be SHARED SSR...” and 1:01:02 - that in the OUTBOUND direction SSR could be SHAPED or SHARED RR 1:21:03 - we have that SHAPED SSR can only be on OUTBOUND and SHARED SSR can be on INBOUND and OUTBOUND
Awesome, nowadays I am involving to reach my CCNP Switch, and Ericsson Cert as well, your information is so helpful for me, I share the same passion for networks much appreciated
this is so good! i am so grateful that you share your knowledge on what seems to be such an indepth and overwhelming task but you make it easy to understand and break it down into a structured approach. I was really struggling without this video and dont think I would have understood qos otherwise.
Hi Kevin, I learnt a lot from this video. I hope you will come up with a complete video series on QoS for the CCIE candidates. Once again thank you for preparing this video.
Hi Kevin, Thanks for this video, it helps a lot to understand the QoS. I was wondering if there is a pdf file available from this presentation ? Thanks again!
***** I really loved the videos from KnowledgeNet. I was amazed how you made teaching something so complicated fun because I was actually learning because you explained things very clearly and I can see you still do. This is the best QOS explanation I've ever seen. Thanks so much for sharing your knowledge.
