EIGRP Variance Command Example

(Rene Molenaar) #1

This topic is to discuss the following lesson:

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(system) #2

Great work. Keep it up …!!!

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(system) #3

thnks…very very good explanation

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(system) #4

Ultimate …awesome explanation

Thank you so much for this great blog

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(system) #5

Good Job…

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(Frades) #6

very precise explanation.
Thanks rene!

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(Raymond C) #7

thank Rene! finally understand this Cisco stuffs!

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(Srinivasan C) #8

Hi Rene,
What is the default behavior of load balancing ? per packet towards destination?
Please explain if there is any command to configure the load balancing method .

Thanks and Regards,
SV

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(Rene Molenaar) #9

Hi SV,

The default of CEF is “per destination” load balancing. You can see it with the show ip cef command. It can be changed on the interface level:

R1(config)#interface FastEthernet 0/0
R1(config-if)#ip load-sharing ?
  per-destination  Deterministic distribution
  per-packet       Random distribution

Rene

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(Srinivasan C) #10

Hi Rene,
Why it is under interface mode ?
What if some interface having default sharing mode and some other having per-packet toward destination?
what is the behavior ? Sorry for getting into the deep. Please point me if you have some links explains more about these load sharing.

Thanks,
SV

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(Rene Molenaar) #11

Hi SV,

It might be interesting to read up on CEF:

Since it’s on the interface, you have the flexibility to change the load balancing per interface…not globally. You can use different load balancing for each interface.

Rene

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(Srinivasan C) #12

Yes. Your are correct. Thanks Rene.

Regards,
SV

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(Navin L) #13

You are the best. Whao…

 

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(Hermann A) #14

Good tutorial. Well explained

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(Idowu A) #15

Thank you so much for this simple and clear explanations.

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(Nikhil M) #16

Do we need to apply the “traffic-share balanced” command if we expect smart load balancing or it is configured as such by default ???

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(Rene Molenaar) #17

Hi Nikhil,

traffic-share balanced is enabled by default for EIGRP so it doesn’t show up in the running-config normally. Take a look below:

Router#show run | begin router eigrp
router eigrp 1
 network 192.168.1.0
Router#show run all | begin router eigrp           
router eigrp 1
 timers active-time 3
 timers graceful-restart purge-time 240
 metric maximum-hops 100
 metric weights 0 1 0 1 0 0
 traffic-share balanced
 variance 1
 network 192.168.1.0
 distance eigrp 90 170
 no auto-summary
 no passive-interface default
 eigrp log-neighbor-changes
 eigrp log-neighbor-warnings 10
 eigrp event-log-size 500
 no shutdown

You can see it in the output of “show run all”.

Rene

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(Nikhil M) #18

Thanks Rene !

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(Farooq A) #19

Hi Rene
Thank you so much for this great blog
I have a one question pls. variance command is used twice on R1 as 3 and 15. Can you please explain how it detect to use which for which route.

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(Andrew P) #20

Farooq,
The variance setting affects the entire EIGRP routing process. It can’t be set on a per-route basis. In the Lesson, Rene changes it from 3 to 15 to show you an example of what happens when the variance increases. It is not meant to be a concurrent configuration. When the second command is issued to change the variance to 15, it is replacing the previous value of 3.

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