Tyson, thank you for the clarification it makes perfect sense now. I will check
out your blog posting.
Steve
________________________________
From: Tyson Scott [mailto:[email protected]]
Sent: Tuesday, December 07, 2010 10:56 AM
To: 'amit chopra'
Cc: Di Bias, Steve; [email protected];
[email protected]; 'Marko Milivojevic'
Subject: RE: [OSL | CCIE_RS] EIGRP unequal cost load
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]<mailto:[email protected]>
Telephone: +1.810.326.1444, ext. 208
Live Assistance, Please visit:
www.ipexpert.com/chat<http://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<http://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]<mailto:[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]<mailto:[email protected]>
Telephone: +1.810.326.1444, ext. 208
Live Assistance, Please visit:
www.ipexpert.com/chat<http://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<http://www.ipexpert.com/communities> and our
public website at www.ipexpert.com<http://www.ipexpert.com/>
From: Di Bias, Steve
[mailto:[email protected]<mailto:[email protected]>]
Sent: Tuesday, December 07, 2010 1:20 PM
To: amit chopra
Cc: Tyson Scott;
[email protected]<mailto:[email protected]>;
[email protected]<mailto:[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]<mailto:[email protected]>]
Sent: Tuesday, December 07, 2010 10:10 AM
To: Di Bias, Steve
Cc: Tyson Scott;
[email protected]<mailto:[email protected]>;
[email protected]<mailto:[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]<mailto:[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]>
[mailto:[email protected]<mailto:[email protected]>]
On Behalf Of Tyson Scott
Sent: Tuesday, December 07, 2010 9:48 AM
To: 'amit chopra';
[email protected]<mailto:[email protected]>;
[email protected]<mailto:[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]<mailto:[email protected]>
Telephone: +1.810.326.1444, ext. 208
Live Assistance, Please visit:
www.ipexpert.com/chat<http://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<http://www.ipexpert.com/communities> and our
public website at www.ipexpert.com<http://www.ipexpert.com/>
From: amit chopra
[mailto:[email protected]<mailto:[email protected]>]
Sent: Tuesday, December 07, 2010 12:22 PM
To: [email protected]<mailto:[email protected]>;
[email protected]<mailto:[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<http://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<http://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
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