From: Ed Tan (tytanx@gmail.com)
Date: Fri Sep 02 2005 - 17:21:45 GMT-3
Thank you Simon and Thomwin for your explanation. I think I had a typo on my
last 2 prefix-list attempt, it should be 24 instead of 14. It works now!
On 9/2/05, simon hart <simon@harttel.com> wrote:
>
> Ed,
>
> The prefix lists you have created are incorrect.
>
> Firstly when creating a prefix list and using the ge and le statements the
> following rules apply
>
> ge must be greater than length value. The length value is the value at the
> end of the prefix i.e. 198.198.0.0/16 <http://198.198.0.0/16>. Therefore
> ge must be a value larger
> than 16
>
> le must be greater or equal than the ge value. Therefore if you have a
> value of 17 for ge, then the value for le must be 17 or greater (up to
> 32).
>
> With that said, it maybe wise to understand what each means. When using ge
> and/or le at the end of the prefix list, then the syntax of the prefix
> list
> changes (from behaviour with no ge or le statements).
>
> Using the following statement as an example
>
> 198.198.0.0/16 <http://198.198.0.0/16> ge 17 le 24
>
> The first part states that the first 16 bits of the prefix must match,
> that
> is 198.198. the last 16 bits can be anything.
>
> The ge 17 means that the subnet mask for the prefix must be at least 17
> bits
> or 255.255.128.0 <http://255.255.128.0>
>
> The le 24 means that the subnet mask for the prefix must be at most 24
> bits
> or 255.255.255.0 <http://255.255.255.0>
>
> Therefore the above statement allows a prefixes that begin with 198.198and
> that have a subnet mask of between 17 and 24 bits.
>
> In order to meet your requirements you are wanting a prefix that starts
> with
> 198.198.x.0 that has only a 24 bit mask. This would be achieved with the
> following
>
> ip prefix-list fil-eigrp permit 198.198.0.0/16 <http://198.198.0.0/16> ge
> 24 le 24
>
> HTH
>
> Simon
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> Ed Tan
> Sent: 02 September 2005 19:58
> To: ccielab@groupstudy.com
> Subject: Ip prefix-list question
>
>
> Hi group,
>
> The question require us "to ignore all routes except 198.198.z.0/24",
> so I try to configure a prefix-list and apply to the distribute-list
>
> router(config)#ip prefix-list filter-eigrp permit
198.198.0.0/16<http://198.198.0.0/16>ge 16 le 24
> % Invalid prefix range for 198.198.0.0/16 <http://198.198.0.0/16>, make
> sure: len < ge-value <=
> le-value
>
> Why I receive this error message? and I also try below which I got the
> same error message?
> router(config)#ip prefix-list fil-eigrp permit
198.198.0.0/16<http://198.198.0.0/16>ge 17 le 14
> router(config)#ip prefix-list fil-eigrp permit
198.198.0.0/16<http://198.198.0.0/16>ge 24 le 14
>
> I hope anyone can provide a solution for the above requirement.
>
> Thanks,
> Ed
>
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