RE: Prefix List Question

From: Scott Morris (smorris@ipexpert.com)
Date: Wed Sep 26 2007 - 20:51:56 ART


That would be any further subnet of 200.2.2.0/24, but let's try it a
different way. Say you wanted to have any RFC 1918 address, but ONLY if it
were /24 subnet mask.
 
ip prefix-list RFC1918 seq 10 permit 10.0.0.0/8 ge 24 le 24
ip prefix-list RFC1918 seq 10 permit 172.16.0.0/12 ge 24 le 24
ip prefix-list RFC1918 seq 10 permit 192.168.0.0/16 ge 24 le 24
 
Same logic. The route must fall within those network ranges. But the mask
must equal /24 (in order to be both less than and greater than at the same
time, we logically wind up with "equal")
 
HTH,
 
 
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE-M
#153, CISSP, et al.
CCSI/JNCI-M/JNCI-ER
VP - Technical Training - IPexpert, Inc.
IPexpert Sr. Technical Instructor
 
A Cisco Learning Partner - We Accept Learning Credits!
 
smorris@ipexpert.com
 
Telephone: +1.810.326.1444
Fax: +1.810.454.0130
http://www.ipexpert.com

  _____

From: groupstudy email [mailto:groupstudy@gmail.com]
Sent: Wednesday, September 26, 2007 4:46 PM
To: smorris@ipexpert.com
Cc: ccielab@groupstudy.com
Subject: Re: Prefix List Question

Scott,

It kind of helps. Thanks for that.

Perhaps a simpler example would drive the point home for me.

What about this:

ip prefix-list test seq 300 permit 200.2.2.0/24 <http://200.2.2.0/24> le 32

What would this include?

Thanks

On 9/26/07, Scott Morris <smorris@ipexpert.com> wrote:

It permits routes where the network portion is from 2.0.0.0 to 2.1.255.255
and the network mask is less than or equal to 32 bits (15-32)

There are two pieces to a prefix list. One says the "network/route" is
within a particular range. The second will give criteria about mask length.

HTH,

Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE-M
#153, CISSP, et al.
CCSI/JNCI-M/JNCI-ER
VP - Technical Training - IPexpert, Inc.
IPexpert Sr. Technical Instructor

A Cisco Learning Partner - We Accept Learning Credits!

smorris@ipexpert.com

Telephone: +1.810.326.1444
Fax: +1.810.454.0130
http://www.ipexpert.com

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
groupstudy email
Sent: Wednesday, September 26, 2007 2:56 PM
To: ccielab@groupstudy.com
Subject: Prefix List Question

Guys,

I have a quick question on prefix-lists. It is difficult to find good info
on this.

What exactly does this line do:

ip prefix-list test seq 300 permit 2.0.0.0/15 le 32

What ranges does it cover.

I'm really confused by this.

Thanks in advance.

S. Rick



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