Hi Marko, Sorry mate, I disagree. I think that Cisco named the LLQ feature to describe the addition of a priority queue to CBWFQ only. In other words, LLQ is the term used for a strict priority queue 'in conjunction with CBWFQ'. In all other cases where a strict priority queue is applied (e.g. strict priority queue with srr, the queue is still known as a priority queue, not llq). I'm happy to be corrected on this but I've not seen any other examples where the acronym llq is used to describe a strict priority queue that is not applied to a policy where the other queuing strategy is CBWFQ. For that reason I think that it is reasonable to associate the two queuing methods when talking about llq.
Having said that, I think this discussion is akin to discussing the difference between lava and magma. I do take your point about the differences in queue behaviours and even implementation but I think that there is a inference that CBWFQ is used whenever LLQ is described. Regards, Andres Villalva On Sat, Jun 25, 2011 at 7:10 AM, Di Bias, Steve <[email protected]>wrote: > Right, but you can certainly understand my argument, since most of the > books I've read tell me otherwise. I surely didn't just make it up. I do > agree that it makes it easier to understand (at least for me) by looking at > it that way, but I understand what you're saying as well. Thanks > > Thank you, > > Steve Di Bias > Network Engineer - Information Systems > Valley Health System - Las Vegas > Office - 702- 369-7594 > Cell - 702-241-1801 > [email protected] > > -----Original Message----- > From: Marko Milivojevic [mailto:[email protected]] > Sent: Friday, June 24, 2011 1:18 PM > To: Di Bias, Steve > Cc: David Swafford; [email protected] > Subject: Re: [OSL | CCIE_RS] LLQ - Is it class based or it's own? > > So, there you go - while it looks and feels like CBWFQ, it's actually > not. Now... should we call it an extension to CBWFQ? I think that's > possible, but personally, I disagree with it, as I think the > differences are significant. > > -- > Marko Milivojevic - CCIE #18427 > Senior Technical Instructor - IPexpert > > FREE CCIE training: http://bit.ly/vLecture > > Mailto: [email protected] > Telephone: +1.810.326.1444 > Web: http://www.ipexpert.com/ > > On Fri, Jun 24, 2011 at 16:16, Di Bias, Steve <[email protected]> > wrote: > > Thank you for the explanation, it makes sense. Looking at your config I > would assume that only 3 queues exist, 1 priority queue for class VOIP-2 and > VOIP-2 and 2 CBWFQ's > > > > > http://www.cisco.com/en/US/docs/ios/12_0t/12_0t7/feature/guide/pqcbwfq.html > > > > "The Low Latency Queueing feature provides strict priority queueing for > CBWFQ, reducing jitter in voice conversations. Configured by the priority > command, Low Latency Queueing enables use of a single, strict priority queue > within CBWFQ at the class level, allowing you to direct traffic belonging to > a class to the CBWFQ strict priority queue. To enqueue class traffic to the > strict priority queue, you configure the priority command for the class > after you specify the named class within a policy map. (Classes to which the > priority command is applied are considered priority classes.) Within a > policy map, you can give one or more classes priority status. When multiple > classes within a single policy map are configured as priority classes, all > traffic from these classes is enqueued to the same, single, strict priority > queue." > > > > Thank you, > > > > Steve Di Bias > > Network Engineer - Information Systems > > Valley Health System - Las Vegas > > Office - 702- 369-7594 > > Cell - 702-241-1801 > > [email protected] > > > > -----Original Message----- > > From: Marko Milivojevic [mailto:[email protected]] > > Sent: Friday, June 24, 2011 1:08 PM > > To: Di Bias, Steve > > Cc: David Swafford; [email protected] > > Subject: Re: [OSL | CCIE_RS] LLQ - Is it class based or it's own? > > > > I will go with yes, but not because authors did not understand the > > concepts, but because that's the simplified way of looking at things. > > In the same fashion as we still call it CBWFQ when it's entirely > > removed from IOS and it does not exist anymore. > > > > LLQ is a strict priority queue and CBWFQ is not. They are different > > queues and in some cases even implemented by different hardware > > components (on platforms that support QoS in ASICS, priority queue is > > separate). However, they are configured in a similar fashion. Just as > > an illustration: > > > > policy-map TEST > > class VOIP-3 > > priority 128 > > class VOIP-2 > > priority 64 > > class A > > bandwidth 128 > > class B > > bandwidth 256 > > ! > > > > How many queues are there? > > > > -- > > Marko Milivojevic - CCIE #18427 > > Senior Technical Instructor - IPexpert > > > > FREE CCIE training: http://bit.ly/vLecture > > > > Mailto: [email protected] > > Telephone: +1.810.326.1444 > > Web: http://www.ipexpert.com/ > > > > On Fri, Jun 24, 2011 at 16:01, Di Bias, Steve <[email protected]> > wrote: > >> Interesting, because there's a lot of material that suggests what I just > said is correct. For example I have found the following excerpts from the > following books: > >> > >> 1) In the Cisco frame relay solutions guide (Cisco Press) Chapt 19 Page > 639 it says: > >> > >> How do LLQ and CBWFQ compare? > >> LLQ is an extended version of CBWFQ, whereby a strict priority queue is > supported for voice or other real-time delay-sensitive traffic > >> > >> Source: > >> > >> > http://books.google.com/books?id=GPuhnmjxLuQC&pg=PA518&lpg=PA518&dq=LLQ+is+an+extension+of+CBWFQ&source=bl&ots=diuxNV_nVi&sig=LkKTD2QVoFcVPqhf65dZVFzevrk&hl=en&ei=qOsETqDtGIn2tgPGm8XfDQ&sa=X&oi=book_result&ct=result&resnum=3&ved=0CCYQ6AEwAjgK#v=onepage&q=LLQ&f=false > >> > >> 2) In the (much older) CCNP BCRAN study guide (Cisco Press) it says: > >> > >> Low-Latency Queuing > >> > >> Low-Latency Queuing (LLQ) is really just an extension of CBWFQ. In fact, > the only real difference between the two is how the bandwidth is allocated > to the class maps in the policy map. > >> > >> Source: > >> > >> http://www.ciscopress.com/articles/article.asp?p=102233&seqNum=5 > >> > >> At Wikipedia (which I know isn't always correct) it says: > >> > >> Low Latency Queuing (LLQ) is a feature developed by Cisco to bring > strict priority queuing (PQ) to Class-Based Weighted Fair Queuing (CBWFQ). > LLQ allows delay-sensitive data (such as voice) to be given preferential > treatment over other traffic by letting the data to be dequeued and sent > first.[1] > >> > >> http://en.wikipedia.org/wiki/Low_Latency_Queuing > >> > >> In the Cisco Frame Relay solutions guide (Cisco Press) Chapt 18 page 383 > it says: > >> > >> With the emergence of voice traffic into data networks the need to > differentiate between the various classes of service has become greater. > PQ/CBWFQ, most commonly known as LLQ, is a new feature that provides a > strict PQ to the CBWFQ scheme. > >> > >> Are all of these books wrong? > >> > >> > >> > >> Thank you, > >> > >> Steve Di Bias > >> Network Engineer - Information Systems > >> Valley Health System - Las Vegas > >> Office - 702- 369-7594 > >> Cell - 702-241-1801 > >> [email protected] > >> > >> -----Original Message----- > >> From: Marko Milivojevic [mailto:[email protected]] > >> Sent: Friday, June 24, 2011 11:55 AM > >> To: Di Bias, Steve > >> Cc: David Swafford; [email protected] > >> Subject: Re: [OSL | CCIE_RS] LLQ - Is it class based or it's own? > >> > >> No, it has nothing to do with CBWFQ. > >> > >> I guess it's easy to grasp the idea of it if you look at it that way > though :-) > >> > >> -- > >> Marko Milivojevic - CCIE #18427 > >> Senior Technical Instructor - IPexpert > >> > >> FREE CCIE training: http://bit.ly/vLecture > >> > >> Mailto: [email protected] > >> Telephone: +1.810.326.1444 > >> Web: http://www.ipexpert.com/ > >> > >> On Fri, Jun 24, 2011 at 13:24, Di Bias, Steve <[email protected]> > wrote: > >>> Marko, isn't LLQ really just an extension of CBWFQ, called PQ/CBWFQ? I > understand it's optional; however they are still tied at the hip, no? > >>> > >>> > >>> Thank you, > >>> > >>> Steve Di Bias > >>> Network Engineer - Information Systems > >>> Valley Health System - Las Vegas > >>> Office - 702- 369-7594 > >>> Cell - 702-241-1801 > >>> [email protected] > >>> > >>> -----Original Message----- > >>> From: [email protected] [mailto: > [email protected]] On Behalf Of Marko Milivojevic > >>> Sent: Friday, June 24, 2011 8:26 AM > >>> To: David Swafford > >>> Cc: [email protected] > >>> Subject: Re: [OSL | CCIE_RS] LLQ - Is it class based or it's own? > >>> > >>> They are different. CBWFQ (starting 12.4(20)T - HQF) and LLQ are > >>> different queueing methods that can co-exist. They are both configured > >>> using MQC and that gives the impression that they are somehow the same > >>> or related, but in reality, they are not. > >>> > >>> LLQ queue is processed first and when that processing is done, other > >>> classes are processed according to their requirements and the queueing > >>> scheduler for CBWFQ/HQF. > >>> > >>> -- > >>> Marko Milivojevic - CCIE #18427 > >>> Senior Technical Instructor - IPexpert > >>> > >>> FREE CCIE training: http://bit.ly/vLecture > >>> > >>> Mailto: [email protected] > >>> Telephone: +1.810.326.1444 > >>> Web: http://www.ipexpert.com/ > >>> > >>> On Thu, Jun 23, 2011 at 13:06, David Swafford <[email protected]> > wrote: > >>>> Hi, > >>>> > >>>> I keep running into this question in my mind.... given a QoS > >>>> configuration w/ a single LLQ and several CBWFQs, would the overal > >>>> policy be consider class-based or LLQ based? > >>>> > >>>> Thanks, > >>>> David. > >>>> _______________________________________________ > >>>> For more information regarding industry leading CCIE Lab training, > please visit www.ipexpert.com > >>>> > >>>> Are you a CCNP or CCIE and looking for a job? Check out > www.PlatinumPlacement.com > >>>> > >>> _______________________________________________ > >>> For more information regarding industry leading CCIE Lab training, > please visit www.ipexpert.com > >>> > >>> Are you a CCNP or CCIE and looking for a job? Check out > www.PlatinumPlacement.com > >>> > >>> > >>> UHS Confidentiality Notice: This e-mail message, including any > attachments, is for the sole use of the intended recipient (s) and may > contain confidential and privileged information. Any unauthorized review, > use, disclosure or distribution of this information is prohibited. If this > was sent to you in error, please notify the sender by reply e-mail and > destroy all copies of the original message. > >> > >> > >> UHS Confidentiality Notice: This e-mail message, including any > attachments, is for the sole use of the intended recipient (s) and may > contain confidential and privileged information. Any unauthorized review, > use, disclosure or distribution of this information is prohibited. If this > was sent to you in error, please notify the sender by reply e-mail and > destroy all copies of the original message. > > > > > > UHS Confidentiality Notice: This e-mail message, including any > attachments, is for the sole use of the intended recipient (s) and may > contain confidential and privileged information. Any unauthorized review, > use, disclosure or distribution of this information is prohibited. If this > was sent to you in error, please notify the sender by reply e-mail and > destroy all copies of the original message. > > > UHS Confidentiality Notice: This e-mail message, including any > attachments, is for the sole use of the intended recipient (s) and may > contain confidential and privileged information. Any unauthorized review, > use, disclosure or distribution of this information is prohibited. If this > was sent to you in error, please notify the sender by reply e-mail and > destroy all copies of the original message. > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > > Are you a CCNP or CCIE and looking for a job? Check out > www.PlatinumPlacement.com > _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com
