EIGRP Variance Command Example

Lessons Discussion
1

This topic is to discuss the following lesson:

2

Great work. Keep it up …!!!

3

thnks…very very good explanation

4

Ultimate …awesome explanation

Thank you so much for this great blog

5

Good Job…

6

very precise explanation.
Thanks rene!

7

thank Rene! finally understand this Cisco stuffs!

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

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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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

11

Hi SV,

It might be interesting to read up on CEF:

https://networklessons.com/switching/cef-cisco-express-forwarding/

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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12

Yes. Your are correct. Thanks Rene.

Regards,
SV

13

You are the best. Whao…

 

14

Good tutorial. Well explained

15

Thank you so much for this simple and clear explanations.

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 ???

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

1 Like
18

Thanks Rene !

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.

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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