Is it generally necessary to add the keyword summary in eigrp stub?

[rookie R]

Hi all!

As far as I know, when you configurate the command, eigrp stub, it automatically add the keyword 'connect' and 'summary' at the end of the command:

When configuring the eigrp stub at work, is it generally necessary to add the summary keyword to advertise the summary routes to neighbors? 

Thanks so much!

[Torbjørn]

A stub router will only advertise routes that are allowed with the "eigrp stub" command. You can choose to only enter "eigrp stub connected" if you don't wish to advertise summary routes. If you wish to advertise summary routes you will either have to specify it, or just enter "eigrp stub" such that it will add it automatically.

[MHM Cisco World]

Yes it mandatory if you want summary to advertise to neighbor. 

MHM

[MHM Cisco World · Accepted solution]

you use 
eigrp stub <<- without any keywords 
and then do 
show run | s r e 
and it appear like 
eigrp stub connected summary <<- this is because by default the eigrp add two keyword if you not specify the prefix you want to allow,

what different between two keyword (also there are other keyword but let talk about it later)
LAB

you can do 
show ip eigrp topology to see which prefix is list as summary and which is list as connected 
then I use two different router each one have  it summary address and each one use different keyword 
R2 with keyword connect advertise only connected to R1
R3 with keyword summary advertise only summary to R1

[rookie R]

Thanks so much for all these details, I got how to use the eigrp stub command now.

My company doesn't use EIGRP on a large scale, so we don't need to use eigrp stub to reduce the eigrp routes, I know my next question is a little bit confusing and silly because how to configure the network depends on the actual conditions, would you please tell me, when configuring the network in actual work, is it common to add the summary keyword? Is advertising the summary EIGRP routes in the stub area in general conditions safe?

[Elliot Dierksen · Accepted solution]

Whether you use summaries depends on your network layout. If you had a large site with a bunch of networks and they were all 10.15.X.X, I would recommend using a summary. If the site only has a couple networks and they don't line up so they can be summarized, then you would advertise connected networks. Summaries are a very good thing to keep your routing table smaller when your IP network assignment is set up so they can be used.

[MHM Cisco World]

Sorry can you more elaborate 

But note You can use summary with and without stub.

MHM

[rookie R]

@Elliot Dierksen answered my question perfectly, Thanks for all the help you guys gave me.

[Gopinath_Pigili]

Hello rookie R,

When you give the "eigrp stub" command without any keyword...it will allow the router to advertise... both Connected networks and summary route.

If your requirement is that the router to send only summary route but not connected networks to the neighbor routers... then you can use eigrp stub summary command.

Best regards
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