Troubleshooting EIGRP Route Advertisement

This topic is to discuss the following lesson:

Hi Rene,

R2#
interface FastEthernet0/0
ip summary-address eigrp 12 172.16.0.0 255.255.0.0 5

 


What does the number 5 mean in the show information above ?

 

And what about leak-map ? when do we use it ?

 

R1(config-if)#ip summary-address ei 1 172.16.0.0 255.255.254.0 ?
leak-map Allow dynamic prefixes based on the leak-map
<cr>

thanks.

Hi Hussein,

The “5” here is the administrative distance of the summary.

The leak-map option can be used to “leak” certain prefixes from your example. You can use this to advertise a prefix that normally falls within the range of your summary.

For example, let’s say you want to advertise summary 172.16.0.0/16 but also one specifix prefix, 172.16.1.0/24. You can use the leak map to get 172.16.1.0/24 “out” of the summary so that it can be advertised.

Rene

Hi Renee,

I didn’t see a topic on this. But is there a way to perform preferred route selection based on a source prefix from the local router? For example lets say I have a router that has two equal cost paths to a network. Let’s say this router has three prefixes it is advertising too. Lets say that only for one prefix will choose one explicit path and the other two prefixes will still use equal load balancing. The config should be made on the local router advertising the prefixes. Can this be done with EIGRP?

Hi Mario,

Routers normally only care about the destination, that’s it.

If you want to make routing decisions based on the source then you can use policy based routing, take a look here:

How to configure policy based routing

Rene

I don’t think this statement is true or at least its not in the perspective i am thinking about it:

“Lesson learned: When you redistribute something into EIGRP you need to configure seed metrics.”

I injected a static route into EIGRP in production and it worked and I did not add any metrics at all.

I basically have talked about it before but I just added a route-map and used a match statement and it showed up in EIGRP on the other router and everything worked great. Before I tried it on production I built a GNS3 lab and tested it.

So am I not understanding correctly what that statemen5t means which is possible I am a bit crazy I am told.

Hello Brian

A clarification is needed here. Seed metrics are needed when redistributing routes from other routing protocols into EIGRP. The redistribution of static routes does not need any seed metrics. Similarly, when redistributing from one EIGRP process into another EIGRP process, metrics are not needed either.

I’ll ask @ReneMolenaar to clarify this in the lesson text.

I hope this has been helpful!

Laz

Thanks for clarifying I think that would be helpful as I ran into same issue with information on the internet its one of those things not clearly defined and made me very timid utilizing it in production. I never found anything anywhere saying seed metrics where not needed I got that from word of mouth from our architects and senior engineers who I had collaborated with before my change request.