But still if you keep max-reserve to 75%, under your classes you can't configure more than 75% of total bandwidth. The command will throw an error of not enough bandwidth if u try to do so. So if all classes are congusted (including default class), u won't get more that 75% on non-default classes. To be to do so you have to raise the max-reserved to 100%.
What you see is caused by min-max approach used by CBWFQ. This means when congestion is happening the minimum garunteed bandwidth for each class will be assigned based on classes configuration. Now if one class (for example the default class) isn't utilizing the mini garunteed bandwidth fully, the extra amount will be distributed among the other classes ; who are demanding more bandwidth, based on weights. I am not saying that Cisco doc is wrong :) ... But saying that the setting isn't effective means that I should be able to configure more bandwidth even if that 75% is there. But in case of congestion in all classes including the default one, you won't get more than 75% on all classes. Regards, Mohammed Al Baqari Sent from my iPhone On Dec 8, 2011, at 12:39 PM, datucha123 datucha123 <datucha...@gmail.com> wrote: > Yes, I have tested it on T - 12.4(22)T version. > > I have made the following tests: > > When configuring the CBWFQ Classes, the sum of bandwidth percent commands > must not exceed 75%. But on my IOS version I could get it to 99% (1% is > reserved for class default), so the document is true for my IOS. > > On Thu, Dec 8, 2011 at 9:08 AM, Mohammed Al Baqari <baqari.voic...@gmail.com> > wrote: > Thanks for sharing the document. As per the document “The resulting common > behavior has been applied to Releases 12.0(26)S and later, future > > 12.2(Rls7)S and T train releases”. > > > > However till 12.4(24)T, I haven’t noticed any changes and the tests I did are > impacted by 75% or 100%. > > > > This doc is dated on 2008, probably they didn’t change after that on T train. > This might be applied to 15.x which I didn’t test yet. > > > > Have you tested this on T train and noticed any difference ? > > > > Regards, > > Mohammed Al Baqari > > > > > > From: ccie_voice-boun...@onlinestudylist.com > [mailto:ccie_voice-boun...@onlinestudylist.com] On Behalf Of datucha123 > datucha123 > Sent: Wednesday, December 07, 2011 3:59 PM > To: ccie_voice@onlinestudylist.com > Subject: [OSL | CCIE_Voice] New Rules for QoS > > > > Hello, > > As we know, there is 75% rule for CBWFQ, so that 25% of the interface > bandwith us used by the Class default, and the remaining 75% can be used for > manully defined classes, so that the sum of BW-s allocated for manually > defined classes must not exceed 75%. > But I have found the following document, which states: > > > New Behavior > > The max-reserved-bandwidth command no longer affects the amount of bandwidth > available to a > > service-policy. 1% must be reserved for the class-default with the rest being > available to the users classes. > > > > http://www.cisco.com/en/US/technologies/tk543/tk545/technologies_white_paper0900aecd8012032d.pdf > >
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