EIGRP Maximum Path and Variance

How can we implement the failover from S0/0 and s0/1 to s0/2? Anybody familiar with the commands?

Read up on maximum-paths and variance.

@ Deep: first you configure variance to increase the FD,
next you cut down the max no of routes allowed by limiting with max-path option.

Wow rene, i thought I'd covered these two topics pretty well for my exam, considering the no of experiments I'd done.
but it never struck me to test both these features at the same time.
thanx!

Glad you liked it, it's fun to mix a few things together

Easy peasy lemon-squeezy. Check show ip eigrp 123 topology all-links to estimate variance required x7 as largest cost is 21154560 and current FD is 3142400. and change maximum-paths to 3 also.

Hi Rene,

In goals you have mentioned that if s0/0 or s0/1 got fails s0/2 needs to takeover.But in video solution you have failed both.

I tried to implement this but facing peculiar problem :
If S0/0 got fails S0/2 will occupy it's position but if S0/1 fails it is not coming up. Do you have any idea bout this ??

Hi Sudheer,

You are right, this is a little confusing. I just changed the goal to "When S0/0 and S0/1 both fail make sure that S0/2 takes over"

S0/0 = successor route
S0/1 = feasible successor route
S0/2 = never shows up in routing table.

When S0/0 and S0/1 both fail there will be a new calculation and S0/2 will be installed as a successor route.

When either S0/0 or S0/1 are down S0/2 can become a feasible successor, it will never be the successor since it has the worst metric of all three interfaces.

It's still possible to configure your routers that S0/2 will take over when either S0/0 or S0/1 fail but it's not an EIGRP solution. You can play around with the "backup interface" command for that.

Does this make sense? If now let me know

Rene

this lab is cool. thanks Rene.

Regards/Asif

Thanks Asif!

Hi Rene,I achieved the goal by playing with metrics so that only S0/0 & S0/1 shown up in routing table and when both S0/0 & S0/1 fails S0/2 takes over.But the problem is when S0/0 & S0/1 comes up ( by giving no shut command) int S0/2 is still shown in routing table.how could this be possible??

FAISAL

Hi Faisal,

Sorry for not responding earlier, I've been very busy migrating the website. To answer your question I would like to see 3 things:

- The output of the routing table.
- The output of the EIGRP topology table.
- Your EIGRP configuration from the running-config.

By default this is how EIGRP behaves:

- First it will choose a successor route and it will look for feasible successors.
- The successors and feasible successors will show up in the EIGRP topology table.
- Only the successor table shows up in the routing table.
- In case you have two equal paths you will see both entries in the routing table.
- Once the successor fails EIGRP will copy/paste the best feasible successor from the EIGRP topology table into the routing table.

EIGRP can also load-balance over feasible successors, in this case both the successor AND the feasible successor will show up in the routing table. You can use the "variance" command to achieve this.

In your case you should check your EIGRP topology table and look which route is the "successor" and which one(s) are feasible successors.

This was an excellent lab. Thanks Rene.

Thank you Rak!

Cool stuff man. Tnx a mil for all these labs

You are welcome, thanks for your message!

Another great lab