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. _______________________________________________ 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
