I hope it helps. Before having doing that blog it often was an area of confusion for myself as well. The numbers never made sense to me.
Regards, Tyson Scott - CCIE #13513 R&S, Security, and SP Managing Partner / Sr. Instructor - IPexpert, Inc. Mailto: <mailto:[email protected]> [email protected] Telephone: +1.810.326.1444, ext. 208 Live Assistance, Please visit: <http://www.ipexpert.com/chat> 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 <http://www.ipexpert.com/communities> www.ipexpert.com/communities and our public website at <http://www.ipexpert.com/> www.ipexpert.com From: amit chopra [mailto:[email protected]] Sent: Tuesday, December 07, 2010 2:00 PM To: Tyson Scott Cc: Di Bias, Steve; [email protected]; [email protected]; Marko Milivojevic Subject: Re: [OSL | CCIE_RS] EIGRP unequal cost load Yes I have readed your blog now and save into my OneNote document. Thanks Tyson On Wed, Dec 8, 2010 at 12:25 AM, Tyson Scott <[email protected]> wrote: If you use the formula's shown on the blog I gave the link below for you shouldn't have any problems. These are exact and never cause me problems. 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: amit chopra [mailto:[email protected]] Sent: Tuesday, December 07, 2010 1:49 PM To: Tyson Scott Cc: Di Bias, Steve; [email protected]; [email protected]; Marko Milivojevic Subject: Re: [OSL | CCIE_RS] EIGRP unequal cost load Thanks Tyson , The forumla which I mentioned is show by other vendor VOD (INE) and rest you know..... On Wed, Dec 8, 2010 at 12:05 AM, Tyson Scott <[email protected]> wrote: IOS rounded the numbers 10^7 / 1544 = 6476.6839.... 25000/10 = 2500 remove the decimal values and you get 6476 & 2500 (6476 + 2500)*256 = 2297856. There is no problem with the formula. IOS simply didn't take it out to the full number. You guys just need to think thru what is happening. 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: Di Bias, Steve [mailto:[email protected]] Sent: Tuesday, December 07, 2010 1:20 PM To: amit chopra Cc: Tyson Scott; [email protected]; [email protected]; Marko Milivojevic Subject: RE: [OSL | CCIE_RS] EIGRP unequal cost load I agree that this is odd, hoping someone can shed some light, how can these formulas lie? Delay = sum of all delays in the path in 10's of microseconds (multiplied) by 256 Bandwidth = [10 o the 7th power / (least bandwidth in kilobits per sec)] * 256 Metric = (bandwidth + delay) _____ From: amit chopra [mailto:[email protected]] Sent: Tuesday, December 07, 2010 10:10 AM To: Di Bias, Steve Cc: Tyson Scott; [email protected]; [email protected]; Marko Milivojevic Subject: Re: [OSL | CCIE_RS] EIGRP unequal cost load Yes Steve , you are right , the result is same. it is alwyas werid becuase most of COD/VOD/Book give this formula and claim it will match but every now then when ever I study this topic I got a differnce in calculation. Look like we may miss something when we calculate metic with given formula. On Tue, Dec 7, 2010 at 11:31 PM, Di Bias, Steve <[email protected]> wrote: Tyson, I used this formula and came up with the same results Delay = sum of all delays in the path in 10's of microseconds (multiplied) by 256 Bandwidth = [10 o the 7th power / (least bandwidth in kilobits per sec)] * 256 Metric = [k1 * bandwidth + (k2 * bandwidth)/(256 - load) + k3 * delay] Or in the case of only K1 and K3 Metric = (slowest link bandwidth) + (sum of all delays) 10000000 / 1544 = 6476.6839378238341968911917098446 x 256 = 1658031 2500 x 256 = 640000 1658031 + 640000 = 2298031 Steve _____ From: [email protected] [mailto:[email protected]] On Behalf Of Tyson Scott Sent: Tuesday, December 07, 2010 9:48 AM To: 'amit chopra'; [email protected]; [email protected]; 'Marko Milivojevic' Subject: Re: [OSL | CCIE_RS] EIGRP unequal cost load Did you go thru this blog. http://blog.ipexpert.com/2010/05/03/eigrp-unequal-cost-load-balancing/ Your numbers are a little off It should be 256 & 10^10 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: amit chopra [mailto:[email protected]] Sent: Tuesday, December 07, 2010 12:22 PM To: [email protected]; [email protected]; Marko Milivojevic; Tyson Scott Subject: EIGRP unequal cost load Always an issue when it is come to calculation :) I watched VOD for EIGRP unequal cost load balacing and try to calculate FD by following formula Rack1R5#show ip eigrp topology 4.0.0.0 IP-EIGRP (AS 100): Topology entry for 4.0.0.0/8 State is Passive, Query origin flag is 1, 2 Successor(s), FD is 2297856 Routing Descriptor Blocks: 155.1.0.4 (Serial1/0.1), from 155.1.0.4, Send flag is 0x0 Composite metric is (2297856/128256), Route is Internal Vector metric: Minimum bandwidth is 1544 Kbit Total delay is 25000 microseconds Reliability is 255/255 Load is 1/255 Minimum MTU is 1500 Hop count is 1 To know how metric calculated on above output , I used following formula: a) 2.56 x 10^12 / BW (in bps) = 2.56 x 1000000000000 / 1544000 = 1658031.0880829015544041450777202 = 1658031 b) Delay : 2500 x 256 = 640000 Metric = a + b = 1658031 + 640000 = 2298031 Now as per output , The metric for 4.0.0.0 is 2297856 and if I subtract both metric it will come up 175 , not sure why it is not match exactly. The 4.0.0.0 prefix is advertise by router 4 : Rack1R4# sh ip eigrp topology 4.0.0.0 IP-EIGRP (AS 100): Topology entry for 4.0.0.0/8 State is Passive, Query origin flag is 1, 1 Successor(s), FD is 128256 Routing Descriptor Blocks: 0.0.0.0 (Loopback4), from Connected, Send flag is 0x0 Composite metric is (128256/0), Route is Internal Vector metric: Minimum bandwidth is 10000000 Kbit Total delay is 5000 microseconds Reliability is 255/255 Load is 1/255 Minimum MTU is 1514 Hop count is 0 Rack1R4# Please guys help 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, and may be punishable by law. If this was sent to you in error, please notify the sender by reply e-mail and destroy all copies of the original message. 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