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Forum Replies

  1. system says:

    Awesome way of explaining!! Thanks..I never EVER Leave a comment anywhere,but could not help here :slight_smile:

  2. Hi @wisamani,

    If you don't supply a wildcard then EIGRP will assume you want the whole network to be advertised. Here's an example:

    Router(config)#router eigrp 1
    Router(config-router)#no auto-summary 

    This is what is stored in the running config:

    Router#show run | begin router eigrp
    router eigrp 1
     network falls under the class A range so that's what EIGRP adds to the running config. If you don't want this, you have to add a wildcard:

    Router(config)#router eigrp 1
    Router(config-router)#no network

    And you will get:

    Router#show run | begin router eigrp
    router eigrp 1

    Even without the wildcard, it would have worked but enabling EIGRP for all 1.x.x.x networks might not be what you want.

    I didn't have to do this for since that's a class C network. If I used a /25 - /30 subnet mask then I would have to add the correct subnet mask.

    Hope this helps!

  3. Hello Rene,

    Your site is great and easy to understand.

    In this topic i understand the part which you had mention if you don't specify the wild card which command is stated below :

    no auto- summary
    router eigrp 1 network  ****

    then in result, you’ll find “network” in your show run.

    However when i read about the topic on RIP - "How to configure RIP on cisco router"

    In the statement
    "You can see that R2 has learned about network /24 and /24. This is because R1 and R3 are advertising /24 and /24, not anymore. R1 and R3 also have learned about each other’s networks."

    I am abit confused because i realize there is no wildcard added for the network command.

    Is there a difference in concept for RIP and EIGRP regarding the network and wildcard command ?

    I mean in another word, no auto-summary for RIP, why i see there is no wildcard for and network ?

    Thank you


  4. Hello Qifeng

    In EIGRP, if you don't use the no auto-summary command, the router will assume a classful network address regardless of the wildcard mask you enter.

    Once you enter the no auto-summary command, EIGRP will begin sending the wildcard mask information as well.

    As for RIP, version 1 will send classful routing information. In order to send classless routing information, RIP must be configured to use Version 2 AND must include the no auto-summary command.

    Now the difference between EIGRP and RIP is that when you configure the network command for RIP, you don't input a wildcard mask. It won't let you. Take a look at this output:

    Router#configure terminal
    Enter configuration commands, one per line.  End with CNTL/Z.
    Router(config)#router rip
    Router(config-router)#version 2
    Router(config-router)#network ?

    The only option it gives you after the network address is <cr>.

    So in RIP, if you configure version 2 and no auto-summary, the router will use the subnet mask configured on the interface associated with the network. So for the example you used, if you have two interfaces with IP addresses and respectively and you configure those networks using RIP, it will use the subnet masks (/24) configured on the interfaces themselves.

    I hope this has been helpful!


  5. That's really helpful, thanks Laz!

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