# EIGRP K Values Formula
**URL:** https://forum.networklessons.com/t/eigrp-k-values-formula/1117
**Category:** Lessons Discussion
**Created:** [December 27, 2016, 3:56pm UTC](https://forum.networklessons.com/t/eigrp-k-values-formula/1117 "2016-12-27T15:56:36Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@ReneMolenaar](https://forum.networklessons.com/u/ReneMolenaar)
#### Post date: [December 27, 2016, 3:56pm UTC](https://forum.networklessons.com/t/eigrp-k-values-formula/1117/1 "2016-12-27T15:56:36Z")
This topic is to discuss the following lesson:
> **[EIGRP K Values Formula](https://networklessons.com/eigrp/eigrp-k-values-formula)**
>
> This lesson explains how EIGRP uses its K values (bandwidth, load, reliability, delay and MTU) to select the best path.
---
### Author:  [@ReneMolenaar](https://forum.networklessons.com/u/ReneMolenaar)
#### Post date: [July 23, 2014, 4:19pm UTC](https://forum.networklessons.com/t/eigrp-k-values-formula/1117/2 "2014-07-23T16:19:33Z")
Hello Rene,
this was a really good post! One statement that I personally dont liked:
“ou don’t want your EIGRP routers calculating 24/7 and sending updates to each other just because the load or reliability of an interface has changed. We want routing protocols to be nice and quiet and only base their routing decisions on static values like bandwidth and delay.”
I think everyone would love to have a routing protocol that dynamically adapts to the network state but the processing overhead for the routers in your network would be a nightmare.
Thank you for this post.
Marek
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### Author:  [@system](https://forum.networklessons.com/u/system)
#### Post date: [September 4, 2014, 2:42pm UTC](https://forum.networklessons.com/t/eigrp-k-values-formula/1117/3 "2014-09-04T14:42:22Z")
Hi Rene,
AFAIK the formula when considered only BW and delay should be:
Metric= [(10^7/ Minimum BW) + (sum of delay/10)] \* 256
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### Author:  [@system](https://forum.networklessons.com/u/system)
#### Post date: [September 5, 2014, 8:24pm UTC](https://forum.networklessons.com/t/eigrp-k-values-formula/1117/4 "2014-09-05T20:24:10Z")
Hello Rene,
Excellent explanation on the metric values used by EIGRP to determine “best” path (route) to take when trying to reach another non-local network. I always was curious how 'best" path was determine by EIGRP when deciding which way to send the packet when multiple paths exists, excellent. Of course this has no real bearing on “stub” networks I take.
Thanks again for your concise explanations on Networking w/ Cisco
Darren
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### Author:  [@ReneMolenaar](https://forum.networklessons.com/u/ReneMolenaar)
#### Post date: [September 11, 2014, 10:32am UTC](https://forum.networklessons.com/t/eigrp-k-values-formula/1117/5 "2014-09-11T10:32:51Z")
Hi Darren,
You are welcome. If you want to take a closer look at this then I can recommend to boot up some routers and look at the EIGRP topology table. Spend some time looking at the successor and feasible successor routers and check why it installed certain things in the routing table.
Rene
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### Author:  [@system](https://forum.networklessons.com/u/system)
#### Post date: [September 30, 2014, 6:59pm UTC](https://forum.networklessons.com/t/eigrp-k-values-formula/1117/6 "2014-09-30T18:59:00Z")
sorry i figured it out, myself, smaller metric is better, its all for influencing, i understand that now, thanks
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### Author:  [@system](https://forum.networklessons.com/u/system)
#### Post date: [November 2, 2014, 3:53pm UTC](https://forum.networklessons.com/t/eigrp-k-values-formula/1117/7 "2014-11-02T15:53:12Z")
EIGRP Metric = 256\*[(K1 x BW) + ((K2 x BW)/(256-Load)) + (K3 x Delay) x ((K5/(Reliability + K4))]
Known as EIGRP “Distance” on the exam.
---
### Author:  [@hussien.samer](https://forum.networklessons.com/u/hussien.samer)
#### Post date: [September 18, 2015, 1:03pm UTC](https://forum.networklessons.com/t/eigrp-k-values-formula/1117/8 "2015-09-18T13:03:00Z")
Hi Rene,
What is the effect of MTU (K5) value to the total metrics ? I mean the metric will be better if the MTU value was high or vice versa ?
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### Author:  [@hussien.samer](https://forum.networklessons.com/u/hussien.samer)
#### Post date: [September 18, 2015, 10:48pm UTC](https://forum.networklessons.com/t/eigrp-k-values-formula/1117/9 "2015-09-18T22:48:52Z")
I notice that you said “the MTU is being exchanged between EIGRP neighbors but not used for the metric calculation” so what is the benefit from this exchanging since it is not used for metric calculation ?
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### Author:  [@hussien.samer](https://forum.networklessons.com/u/hussien.samer)
#### Post date: [September 19, 2015, 2:30pm UTC](https://forum.networklessons.com/t/eigrp-k-values-formula/1117/10 "2015-09-19T14:30:29Z")
Hi Rene,
I understood that if the delay was in ten of microsecond we only sum the delays of the links and if the delay was in microsecond we need to divide the sum on 10 and put the value to formula, and about BW I do not understand why we multiply by 10^7 when I read in Wiki I understand the we do that to make the formula weighted and make measuring units harmonized but I do not understand how ? I mean why 10^7 ? from where this number come ?
---
### Author:  [@hussien.samer](https://forum.networklessons.com/u/hussien.samer)
#### Post date: [September 20, 2015, 8:18pm UTC](https://forum.networklessons.com/t/eigrp-k-values-formula/1117/11 "2015-09-20T20:18:20Z")
Hi Rene,
Is there a formula to calculate the the AD ( Advertised Distance ) ?
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### Author:  [@hussien.samer](https://forum.networklessons.com/u/hussien.samer)
#### Post date: [September 22, 2015, 1:03am UTC](https://forum.networklessons.com/t/eigrp-k-values-formula/1117/12 "2015-09-22T01:03:48Z")
Hi Rene,
What is the threshold value of FD ( the metric value ) that indicates to infinity ?
thanks.
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### Author:  [@ReneMolenaar](https://forum.networklessons.com/u/ReneMolenaar)
#### Post date: [September 24, 2015, 2:22pm UTC](https://forum.networklessons.com/t/eigrp-k-values-formula/1117/13 "2015-09-24T14:22:06Z")
EIGRP uses a 32 bit metric so the value used for infinity is 4294967295, the highest value you can create.
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### Author:  [@ReneMolenaar](https://forum.networklessons.com/u/ReneMolenaar)
#### Post date: [September 24, 2015, 4:23pm UTC](https://forum.networklessons.com/t/eigrp-k-values-formula/1117/14 "2015-09-24T16:23:08Z")
Hi Hussein,
The MTU doesn’t influence the metric, it’s not used in the metric calculation.
Rene
---
### Author:  [@ReneMolenaar](https://forum.networklessons.com/u/ReneMolenaar)
#### Post date: [September 24, 2015, 4:26pm UTC](https://forum.networklessons.com/t/eigrp-k-values-formula/1117/15 "2015-09-24T16:26:58Z")
Apparently when you have two equal cost paths and EIGRP has to select one of them, it will use the path with the highest MTU. The low MTU path will not be used.
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### Author:  [@ReneMolenaar](https://forum.networklessons.com/u/ReneMolenaar)
#### Post date: [September 24, 2015, 5:40pm UTC](https://forum.networklessons.com/t/eigrp-k-values-formula/1117/16 "2015-09-24T17:40:36Z")
Hi Hussein,
Good question, I tried to look it up but I couldn’t find anything why they picked 10^7…can’t find any explanation.
Rene
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### Author:  [@ReneMolenaar](https://forum.networklessons.com/u/ReneMolenaar)
#### Post date: [September 24, 2015, 7:14pm UTC](https://forum.networklessons.com/t/eigrp-k-values-formula/1117/17 "2015-09-24T19:14:22Z")
Hi Hussein,
The advertised distance that a router advertises to a neighbor is the feasible distance that it has stored for a route, it’s the same calculation.
Rene
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### Author:  [@dmsanch1](https://forum.networklessons.com/u/dmsanch1)
#### Post date: [November 23, 2015, 9:35pm UTC](https://forum.networklessons.com/t/eigrp-k-values-formula/1117/18 "2015-11-23T21:35:23Z")
Hi Rene,
> Here you see the result of changing the bandwidth on the interface. Something to remember is that **EIGRP will use the highest bandwidth in the path from A to B (since this is the bottleneck).**
Is this right?. A think that EIGRP use the **lowest** bandwitch.
Thanks you
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### Author:  [@ReneMolenaar](https://forum.networklessons.com/u/ReneMolenaar)
#### Post date: [November 24, 2015, 1:31pm UTC](https://forum.networklessons.com/t/eigrp-k-values-formula/1117/19 "2015-11-24T13:31:26Z")
Hi Diego,
That is correct, I just fixed it. Thanks for reporting!
Rene
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### Author:  [@villegas\_702](https://forum.networklessons.com/u/villegas_702)
#### Post date: [May 6, 2017, 2:03am UTC](https://forum.networklessons.com/t/eigrp-k-values-formula/1117/20 "2017-05-06T02:03:53Z")
> [@hussien.samer](#):
>
> Hi Rene,
>
> I understood that if the delay was in ten of microsecond we only sum the delays of the links and if the delay was in microsecond we need to divide the sum on 10 and put the value to formula, and about BW I do not understand why we multiply by 10^7 when I read in Wiki I understand the we do that to make the formula weighted and make measuring units harmonized but I do not understand how ? I mean why 10^7 ? from where this number come ?
I’m about 2 years too late but I’d like to take a crack at this for future reference. The reason 10^7 is used is because 10^7=10,000,000 kbps which is the same things as 10Gbps. When this formula was developed into what it is today, 10gbps was insanely, insanely fast and was decided to be used as the number utilized to calculate the weight of the minimum bandwidth number in the EIGRP formula.
The reason that we are adding weight to each number in EIGRP is easy to understand. EIGRP is a complex formula with different sets of numbers that have _varying_ levels of relevance. We decide how much weight, or relevance, the minimum bandwidth has by taking 10^7 (dividend) and dividing it by the minimum bandwidth (divisor), the resulting number (quotient) multiplied by 256 [Read: 2^8 ‘binary octet max value’] is your _weighted_ bandwidth.
“The multiplication of 256 is done so EIGRP is compatible with IGRP (the predecessor of EIGRP).”
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