*4 is approximate. I would stick with the first. Access Rate (AR) = Bc + Be
Regards, Tyson Scott - CCIE #13513 R&S, Security, and SP Managing Partner / Sr. Instructor - IPexpert, Inc. Mailto: [email protected] Telephone: +1.810.326.1444, ext. 208 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 <http://www.ipexpert.com/> From: [email protected] [mailto:[email protected]] On Behalf Of Roy Shaver Sent: Monday, August 16, 2010 7:03 PM To: [email protected] Subject: [OSL | CCIE_RS] FR Traffic Shaping Clarification I understand Tc=Bc/CIR which makes perfect sense. I have found in my studies that confuse what Be should be. For example if I have a 64k CIR and am allowed to burst to 256k and you need to set the configuration such that Tc equals 200ms or 1/5Sec. And as I understand Bc + Be = Burst then the math should be as follows: Tc = Bc / CIR CIR = 64000 Tc = 200ms or 1/5 Bc = 64000/5 = 12800 So all straight forward so far... Now to figure Be. (Bc + Be) * 5 = 256000 (12800 + Be) * 5 = 256000 Some math I couldn't figure out how to write in the e-mail.... Be = 38400 Thus (12800 + 38400) * 5 = 256000 Now here is were the confusion sets in.... Some examples I have read and seen people are saying since 256k is 4 time 64k then multiply Bc times 4 and you have Be. But when I do that the math works out that you would be bursting to 320k not 256k. (12800 + 51200) * 5 = 320000 So the question is, Do you add Bc to Be to calculate the burst or do you do as some of the examples I have seen do and multiple it by whatever. I was sure I was doing it right until I saw some examples do it differently. Thanks, Roy S.
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