EIGRP variance configuration issue [SOLVED]

[blue phoenix]

Hi all,

I have been doing this in a Virtual lab environment.  As you can see below the FR router is just a frame relay switch and is not doing any routing....  I am trying to achieve unequal cost load-balancing by using the variance feature...

Here is the sh ip eigrp top of R2 if trying to reach loopback of R1
R2#sh ip eigrp top | s 111.111.4.0
P 111.111.4.0/24, 1 successors, FD is 196689920
via 10.23.0.3 (196689920/131153920), Ethernet0/2
via 10.12.0.1 (1735257878/163840), Serial1/2

As you can see the path of Serial1/2's RD is lower than FD of best path, hence it is shown in the topology table....

But in the RT it is showing only 1 path to the network 111.111.4.0
R2#sh ip route eigrp | b 111.
111.0.0.0/8 is variably subnetted, 12 subnets, 2 masks
D 111.111.4.0/24 [90/1536640] via 10.23.0.3, 00:10:39, Ethernet0/2
D 111.111.5.0/24 [90/1536640] via 10.23.0.3, 00:10:39, Ethernet0/2
D 111.111.6.0/24 [90/1536640] via 10.23.0.3, 00:10:39, Ethernet0/2
D 111.111.7.0/24 [90/1536640] via 10.23.0.3, 00:10:39, Ethernet0/2

From understanding the videos and docs, in order to calculate the variance number, you need to divide the FD of the worst path to the FD of the best path.
1735257878 / 196689920 = 8.82 or 9

I have tried variance 9 or 10 but I can't seem to put the serial interface in the RT.

Can anyone please help on what I am missing on the concept?

Cheers,

[blue phoenix]

NOTE to self...

Variance is configured on the router that wants to load-balance to the destination network.  Therefore the metric is changed locally on the router that sees the route.

[PaulP]

You are trying to loadbalance across 2 different link types, ethernet and serial. CEF is working against you on this. Kill CEF or tweak it. More below:

https://www.cisco.com/c/en/us/support/docs/ip/enhanced-interior-gateway-routing-protocol-eigrp/13677-19.html

You can also move the 111.111.x.x networks behind FR and R3 Router to achieve this.

Good luck,

Paul

[blue phoenix · Accepted solution]

My mistake is to configure variance on the Router that is advertising the
prefix or subnet. When I configured the variance on the router that sees
the advertised network everything worked like a charm.

[blue phoenix]

Hi,

CEF has nothing to do with the issue I encountered.  I just need to put the variance configuration on the router that is seeing the subnet and NOT on the router that is advertising that subnet.

Cheers,

[Predrag Jovic]

Somehow you have two different metrics:

R2#sh ip eigrp top | s 111.111.4.0

P 111.111.4.0/24, 1 successors, FD is 196689920
via 10.23.0.3 (196689920/131153920), Ethernet0/2

R2#sh ip route eigrp | b 111.
111.0.0.0/8 is variably subnetted, 12 subnets, 2 masks
D 111.111.4.0/24 [90/1536640] via 10.23.0.3, 00:10:39, Ethernet0/2

Those two should match.

If you calculate 1536640 * 10 = 15366400 and  it is still < 1735257878

[blue phoenix]

Hi,

Everything is working normally.  I just need to configure the variance on the router that sees the route and not on the router that advertises it.

Cheers,