Hey Ed and group!

Remember, the prefix-list is a strange cookie -- Depending on the
syntax / parameters the meaning changes completely!

For example:

This will match the exact prefix 100.100.100.0 with a /24 mask
ip prefix-list pants permit 100.100.100.0/24

This will match anything where the first 3 octets are 100 and ANY
subnet mask...i.e 100.100.100.0/x where x is ANYTHING. It is now much
broader and the / piece of the syntax has changed completely...we are
now talking about the network portion of the prefix and not the subnet
mask

ip prefix-list pants permit 100.100.100.0/24 le 32





On Sun, May 2, 2010 at 6:01 PM, Bodnar, Edward <[email protected]> wrote:
> I agree not sure why someone would do that but Believe it or not it helped
> to clarify for me.
>
>
>
> From: Adam [mailto:[email protected]]
> Sent: Sunday, May 02, 2010 5:59 PM
> To: Bodnar, Edward
> Cc: [email protected]
> Subject: Re: [OSL | CCIE_RS] Vol 3 Lab 1 Task 3.3
>
>
>
> Needless to say that does not look good :) If I recall correctly, IOS won't
> accept such entry in prefix-list, "le y" should not be lower than value
> specified with "/x".
>
> On Sun, May 2, 2010 at 11:43 PM, Adam <[email protected]> wrote:
>
> That means "I want to match networks with 201.2 in the first two octets, but
> subnet mask should be 255.0.0.0 or less".
>
>
>
> On Sun, May 2, 2010 at 11:26 PM, Bodnar, Edward <[email protected]>
> wrote:
>
> So is this valid?
>
> Ip prefix-list EIGRP permit 201.2.0.0/16 le 8
>
>
>
> From: Adam [mailto:[email protected]]
> Sent: Sunday, May 02, 2010 5:21 PM
> To: Bodnar, Edward
> Cc: [email protected]
> Subject: Re: [OSL | CCIE_RS] Vol 3 Lab 1 Task 3.3
>
>
>
> 201.2.0.0/16 means 201.2/16 subnet only, exactly this prefix, first 16 bits
> have to be 201.2 and subnet mask must be set to 255.255.0.0  (in JunOS
> route-lists there is an "exact" word for that). Exactly what you have
> specified and nothing else.
> 201.2.0.0/16 le 32 means that the first two octets still have to be 201.2,
> but subnet masks can vary from /16 up to /32, which means that it covers
> also subnets falling into 201.2/16 range. Match 201.2/16, don't care about
> last two octets, but subnet mask must fall into <255.255.0.0;
> 255.255.255.255> range.
>
> On Sun, May 2, 2010 at 11:06 PM, Bodnar, Edward <[email protected]>
> wrote:
>
> Prefix lists are still getting me.
>
>
>
> In this task I did not use the le 32 and the end of my entries.   Not sure I
> understand why I would need that
>
>
>
> Example
>
>
>
> Ip prefix-list Ed permit 201.2.0.0/16  ß what I used
>
> Ip prefix-list EIGRP permit 201.2.0.0/16 le 32  ß answer key used
>
>
>
>
>
> Ed,
>
>
>
>
>
> _______________________________________________
> For more information regarding industry leading CCIE Lab training, please
> visit www.ipexpert.com
>
> _______________________________________________
> For more information regarding industry leading CCIE Lab training, please
> visit www.ipexpert.com
>
>



-- 
Regards,



Joe Astorino - CCIE #24347
Sr. Technical Instructor - IPexpert
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