A tiny bit of help needed with IP Prefix list

MrXpertMrXpert Member Posts: 586 ■■■□□□□□□□
in CCNP
how do you prevent all /24 subnets in a prefix list?
i tried 0.0.0.0/24 thinking that may work but it didn't.

I also want to know how to prevent all subnets with a /24 to /28 inclusive
I tried seq 5 deny 0.0.0.0/24 le 28 and then a seq 10 permit 0.0.0.0/0 le 32 on the last line. It didn't work.


Please help.
I'm an Xpert at nothing apart from remembering useless information that nobody else cares about.
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Comments

  • Nate--IRL--Nate--IRL-- Member Posts: 103 ■■□□□□□□□□
    Maybe something like?

    ip prefix-list PRFX deny 10.0.0.0/8 ge 24 le 24

    Now that you ask I'm not sure - I'll have to check.

    Nate
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  • nomanenomane Member Posts: 15 ■□□□□□□□□□
    Have you tried [FONT=Verdana, Helvetica, sans-serif]0.0.0.0/0 ge 24 le 24?[/FONT]
    CCDA ( ) - Dec 2012
    CCDP ( ) - 2013
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  • networker050184networker050184 Mod Posts: 11,962 Mod
    ^ That was going to be my suggestion.
    An expert is a man who has made all the mistakes which can be made.
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  • wavewave Member Posts: 342
    How are you applying the prefix-list? Are you using a distribute-list? Route-map?

    If you're using a route-map remember that it's the permit and deny statements in the route-map not the prefix-list that control permit/deny.

    If you're using a distribute-list, what you had should work. I just tested this:

    ip prefix-list TESTER seq 5 deny 0.0.0.0/24 le 28

    router eigrp 1
    distribute-list prefix TESTER in
    ROUTE Passed 1 May 2012
    SWITCH Passed 25 September 2012
    TSHOOT Passed 23 October 2012
    Taking CCNA Security in April 2013 then studying for the CISSP
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  • networker050184networker050184 Mod Posts: 11,962 Mod
    Are you sure that is working as planned? What you are saying is match anything with the first 24 bits all zeros. If all you have configured is what you have listed it will block all routes.
    An expert is a man who has made all the mistakes which can be made.
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  • wavewave Member Posts: 342
    Yes you're right, it was blocking all routes.
    ROUTE Passed 1 May 2012
    SWITCH Passed 25 September 2012
    TSHOOT Passed 23 October 2012
    Taking CCNA Security in April 2013 then studying for the CISSP
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  • wavewave Member Posts: 342
    ip prefix-list TESTER seq 5 deny 0.0.0.0/0 ge 24 le 24
    ip prefix-list TESTER seq 10 permit 0.0.0.0/0 le 32
    ROUTE Passed 1 May 2012
    SWITCH Passed 25 September 2012
    TSHOOT Passed 23 October 2012
    Taking CCNA Security in April 2013 then studying for the CISSP
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  • MrXpertMrXpert Member Posts: 586 ■■■□□□□□□□
    nomane wrote: »
    Have you tried 0.0.0.0/0 ge 24 le 24?

    cool! thanks that sorted it!icon_cheers.gif
    I'm an Xpert at nothing apart from remembering useless information that nobody else cares about.
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