Adam is right on -- congestion avoidance and queueing are two different things. You can configure your congestion avoidance (WRED) so that it takes into consideration the DSCP values when deciding what traffic to randomly drop first
On Tue, May 4, 2010 at 10:17 AM, Adam <[email protected]> wrote: > That's why you can use CB-WRED based on DSCP. Scheduling and congestion > avoidance are two separate things. > > On Tue, May 4, 2010 at 9:10 AM, Fabio Mendes <[email protected]> > wrote: >> >> I thought just like you: it is used only within classes. But I cannot >> grasp the whole thing at all. >> In order to avoid tail droping when a queue reachs a certain threshold - >> depending on the queue discipline - some packets are "ramdomly" discarded. >> If all the queues are avoiding tail droping, discarding some part of >> incoming traffic and those two packets arrived, which one would be more >> "likely" to be discarded ? AF marking plays no role in such a situtation ? >> >> Thank you for answering. >> >> On Tue, May 4, 2010 at 10:43 AM, Marko Milivojevic <[email protected]> >> wrote: >>> >>> It depends... :-) What scheduler are you talking about exactly? Drop >>> precedence is used to differentiate within the same class, not between >>> the classes. AF11 is in CS1 and AF23 is in CS2... It's similar to >>> scheduler chosing bananaes while being offered apples and oranges... >>> :-) >>> >>> -- >>> Marko Milivojevic - CCIE #18427 >>> Senior Technical Instructor - IPexpert >>> >>> YES! We include 400 hours of REAL rack >>> time with our Blended Learning Solution! >>> >>> Mailto: [email protected] >>> Telephone: +1.810.326.1444 >>> Fax: +1.810.454.0130 >>> Web: http://www.ipexpert.com/ >>> >>> On Tue, May 4, 2010 at 13:21, Fabio Mendes <[email protected]> >>> wrote: >>> > >>> > Suppose I have two packets: one marked as AF11 and another one marked >>> > as >>> > AF23. >>> > If the scheduler were to choose between one of them, which one would be >>> > ? >>> > >>> > Despite the fact that AF23 packet belongs to a queue that is suppose to >>> > get >>> > a better queueing treatment it has the higher probability to be >>> > discarded. >>> > In the other hand, AF11 packet belongs to a lower priority queue but it >>> > has >>> > the lowest discarding probabability. >>> > How does the scheduler decide which packet to send to the hardware >>> > queue ? >>> > >>> > >>> > Thanks ! >>> > -- >>> > >>> > _______________________________________________ >>> > For more information regarding industry leading CCIE Lab training, >>> > please >>> > visit www.ipexpert.com >>> > >>> > >> >> >> >> -- >> >> CCNA - Cisco Certified Network Associate >> CCNP - Cisco Certified Network Professional >> >> "A bird that you set free may be caught again, but a word that escapes >> your lips will not return." Jewish Proverb >> >> _______________________________________________ >> For more information regarding industry leading CCIE Lab training, please >> visit www.ipexpert.com >> > > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > > -- Regards, Joe Astorino - CCIE #24347 Sr. Technical Instructor - IPexpert Mailto: [email protected] Telephone: +1.810.326.1444 Live Assistance, Please visit: www.ipexpert.com/chat eFax: +1.810.454.0130 IPexpert is a premier provider of Self-Study Workbooks, Video on Demand, Audio Tools, Online Hardware Rental and Classroom Training for the Cisco CCIE (R&S, Voice, Security & Service Provider) certification(s) with training locations throughout the United States, Europe, South Asia and Australia. Be sure to visit our online communities at www.ipexpert.com/communities and our public website at www.ipexpert.com _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
