Re: EIGRP K values

I still like the link that Piotr referenced, because it is how it actually
works, especially if K5 is manipulated. But i also agree that no one
manipulates the K values, especially K5. But the 12.4 link provides the
correct formula.

On Thu, Oct 7, 2010 at 6:52 AM, Carlos G Mendioroz <tron_at_huapi.ba.ar> wrote:

> Nobody pays attention to the formulas, statistically speaking :)
> Cisco has, for quite a long time, copy & pasted a phrase that said that
> EIGRP metric had MTU involved in the computation. Not so, although EIGRP
> does carry MTU as part of the path data, and it could have used it...
>
> Does anybody know of anyone using Ks for dynamic load balancing based on
> anything that is not the default ?
>
> -Carlos
>
> Tyson Scott @ 7/10/2010 10:42 -0300 dixit:
>
> This is the formula that is used by default since K1 and K3 are 1 by
>> default
>> and the rest are 0.
>> EIGRP Metric = 256*((10^7 / min. Bw) + Delay in micro sec/10)
>>
>> Take a look at the following blog articles if you want to know more.
>> http://blog.ipexpert.com/2010/03/03/eigrp-metric-k-values/
>> http://blog.ipexpert.com/2010/05/03/eigrp-unequal-cost-load-balancing/
>>
>> The first one is more relevant to this topic
>>
>> Regards,
>> Tyson Scott - CCIE #13513 R&S, Security, and SP
>> Managing Partner / Sr. Instructor - IPexpert, Inc.
>> Mailto: tscott_at_ipexpert.com
>>
>>
>> -----Original Message-----
>> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
>> Narbik Kocharians
>> Sent: Thursday, October 07, 2010 9:27 AM
>> To: Piotr Malarski
>> Cc: Cisco certification
>> Subject: Re: EIGRP K values
>>
>> Hahahaha
>>
>> Both links are from Cisco. Amazing, i did not pay attention to that.
>>
>> But Both formulas will result to the same composite metric unless the K5
>> value is manipulated. Now that i look at both of them a little more
>> carefully, i would go with your link. I think they have a typo in the link
>> that i provided.
>>
>> On Thu, Oct 7, 2010 at 6:12 AM, Piotr Malarski
>> <piotr.malarski.99_at_gmail.com>wrote:
>>
>> The formula from the link that you provided is not the same as the
>>> formula from the DOC CD available during lab.
>>>
>>> #1 : Formula from your link:
>>> metric = [K1 * bandwidth + (K2 * bandwidth) / (256 - load) + K3 *
>>> delay] * [K5 / (reliability + K4)]
>>>
>>> #2 : Formula from DOC CD, IOS 12.4 Configuration guide
>>> metric = 256*((K1*Bw) + (K2*Bw)/(256-Load) + (K3*Delay)*(K5/(Reliability
>>> +
>>> K4)))
>>>
>>> The differences are:
>>> a. Compare how K values are grouped with brackets in both formulas. If
>>> K5=1 then calculation is different in formula #1 and #2
>>> b. In #2 there is multiplication by 256, not in #1
>>>
>>> One of them (or both) must be wrong. Which one ?
>>>
>>> I am referring to this DOC CD article:
>>>
>>>
>>>
>> http://www.cisco.com/en/US/docs/ios/iproute_eigrp/configuration/guide/ire_cf
>> g_eigrp_ps6350_TSD_Products_Configuration_Guide_Chapter.html
>>
>>>
>>> On Thu, Oct 7, 2010 at 4:44 AM, Narbik Kocharians <narbikk_at_gmail.com>
>>> wrote:
>>>
>>>> If K5 is set to it's default value (Which is zero), the last portion of
>>>>
>>> the
>>> > formula (K5/K4+rel) will not come into play:
>>>
>>>>
>>>>
>> http://www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a0080094c
>> b7.shtml
>>
>>>
>>>>
>>>> On Thu, Oct 7, 2010 at 1:09 AM, Elias Chari <elias.chari_at_gmail.com>
>>>>
>>> wrote:
>>>
>>>> Yes, the maths do not work out when you look at it that way. May be
>>>>> another
>>>>> way to represent the formula, which may make it easier to interpret
>>>>>
>>>> would
>>>
>>>> be:
>>>>>
>>>>> (a) For K5>0, the formula applied by the router is:
>>>>>
>>>>> EIGRP Metric = 256*((K1*Bw) + (K2*Bw)/(256-Load) +
>>>>> (K3*Delay)*(K5/(Reliability + K4)))
>>>>>
>>>>> (b) For K5=0, the formula applied by the router is:
>>>>>
>>>>> EIGRP Metric = 256*((K1*Bw) + (K2*Bw)/(256-Load) + (K3*Delay))
>>>>>
>>>>>
>>>>> On 7 October 2010 07:53, Narbik Kocharians <narbikk_at_gmail.com> wrote:
>>>>>
>>>>> If K5 is set to zero (Which is the default), then, the last section
>>>>>>
>>>>> of
>>
>>> the
>>>>>
>>>>>> formula (K5/(Reliability + K4) will not come into play.
>>>>>>
>>>>>> On Wed, Oct 6, 2010 at 9:18 PM, Piotr Malarski
>>>>>> <piotr.malarski.99_at_gmail.com>wrote:
>>>>>>
>>>>>> Hello,
>>>>>>>
>>>>>>> What should be K values so only delay is used to calculate the
>>>>>>>
>>>>>> metric ?
>>>
>>>> OK, I know that the answer is 0 0 1 0 0 (K1,K2,K3,K4,K5) but this
>>>>>>>
>>>>>> does
>>>
>>>> not fit the Doc CD formula:
>>>>>>>
>>>>>>> EIGRP Metric = 256*((K1*Bw) + (K2*Bw)/(256-Load) +
>>>>>>> (K3*Delay)*(K5/(Reliability + K4)))
>>>>>>>
>>>>>>> If K3=1 and K4=K5=0 then the last section of the above formula
>>>>>>>
>>>>>> equals
>>>
>>>> 0 and Delay will not be considered at all:
>>>>>>>
>>>>>>> (1*Delay)*(0/(Reliability + 0)) = (1*Delay)*0 = 0
>>>>>>>
>>>>>>> Actually, if K values are 00100 then the whole metric equals zero.
>>>>>>>
>>>>>> I
>>
>>> thinks that my math is correct. Can someone please clarify ?
>>>>>>>
>>>>>>>
>>>>>>> Blogs and organic groups at http://www.ccie.net
>>>>>>>
>>>>>>>
>>>>>>>
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>>>>>>>
>>>>>>>
>>>>>>>
>>>>>> --
>>>>>> Narbik Kocharians
>>>>>> CCSI#30832, CCIE# 12410 (R&S, SP, Security)
>>>>>> www.MicronicsTraining.com <http://www.micronicstraining.com/> <
>>>>>> http://www.micronicstraining.com/> <
>>>>>>
>>>>> http://www.micronicstraining.com/> <
>>>
>>>> http://www.micronicstraining.com/>
>>>>>
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>>>> --
>>>> Narbik Kocharians
>>>> CCSI#30832, CCIE# 12410 (R&S, SP, Security)
>>>> www.MicronicsTraining.com <http://www.micronicstraining.com/> <
>>>> http://www.micronicstraining.com/>
>>>> Sr. Technical Instructor
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>>
>>
> --
> Carlos G Mendioroz <tron_at_huapi.ba.ar> LW7 EQI Argentina
>

-- 
Narbik Kocharians
CCSI#30832, CCIE# 12410 (R&S, SP, Security)
www.MicronicsTraining.com
Sr. Technical Instructor
YES! We take Cisco Learning Credits!
Training And Remote Racks available
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