# Help with EIGRP and variance

Apr 26th, 2009

All,

I have set up a lab in gns3 with eigrp to test the variance command. I have the following routes on one router:

<b>D 100.100.100.0 [90/435200] via 10.0.0.2, 00:01:24, Ethernet0/2

[90/435200] via 50.50.50.2, 00:01:24, Ethernet0/1</b>

My topology table shows three entries:

<b>P 100.100.100.0/24, 2 successors, FD is 435200

via 50.50.50.2 (435200/409600), Ethernet0/1

via 10.0.0.2 (435200/409600), Ethernet0/2

via 10.25.25.2 (45893376/153856), Ethernet0/0</b>

With a variance of 3 (3*153856=461568), I should see the third entry via e0/0 in my routing table, correct? Am I miscalculating, or will only two routes at a time only show up in the routing table?

Thanks,

John

John,

via 10.25.25.2 (45893376/153856), Ethernet0/0. Well,153856-RD < 435200-FD. But 45893376 divided by 435200. The result is 105.45. What about the following commands.

!

router eigrp XXX

variance 106

!

HTH,

Toshi

John:

Good morning.

You are making a mistake with the calculation.

Its not 3 x 152,856...

It should be 3 x 435,200...which is about 1,300,000

Your total metric cost for the 3rd route is 45,893,376...

That is more than 100 times the cost of the primary routes (successors).

You have to compare the overall metrics, not just the FD of one candidate route to the FD of the successor...

HTH

Victor

Overall Rating: 5 (2 ratings)

## Replies

lamav Sun, 04/26/2009 - 06:40

John:

Good morning.

You are making a mistake with the calculation.

Its not 3 x 152,856...

It should be 3 x 435,200...which is about 1,300,000

Your total metric cost for the 3rd route is 45,893,376...

That is more than 100 times the cost of the primary routes (successors).

You have to compare the overall metrics, not just the FD of one candidate route to the FD of the successor...

HTH

Victor

thotsaphon Sun, 04/26/2009 - 06:40

John,

via 10.25.25.2 (45893376/153856), Ethernet0/0. Well,153856-RD < 435200-FD. But 45893376 divided by 435200. The result is 105.45. What about the following commands.

!

router eigrp XXX

variance 106

!

HTH,

Toshi

thotsaphon Sun, 04/26/2009 - 06:45

Hi Victor,

How are you going? Seems we did at the same time. Let's start with math calculation for today. (grin)

Toshi