RE: Block some IP address from other router

From: Scott Morris (swm@emanon.com)
Date: Wed Apr 26 2006 - 13:03:51 GMT-3


4 = 00000100
5 = 00000101
6 = 00000110
7 = 00000111
12 = 00001100
13 = 00001101
14 = 00001110
15 = 00001111
     ^^^^x^xx = Differences (^ = same, x = different)

A mask of 10 would match 4, 6, 12, 14 only.
Notice that the 1-bit position varies as well.

How about a mask of 0.0.11.0? That will give you 3 bits in the mask. 2^3 =
8 matches, and you have 8 networks listed!

HTH,

 
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE
#153, CISSP, et al.
CCSI/JNCI
IPExpert CCIE Program Manager
IPExpert Sr. Technical Instructor
smorris@ipexpert.com
http://www.ipexpert.com
 

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Albert Ip
Sent: Wednesday, April 26, 2006 5:44 AM
To: ccielab@groupstudy.com
Subject: Block some IP address from other router

Hi,

e.g.
R1 and R2 are running RIP, R2 is advistering the following RIP routes...
192.168.1.0/24 to 192.168.16.0/24

However, in R1 routing table, only see....
192.168.4.0
192.168.5.0
192.168.6.0
192.168.7.0
192.168.12.0
192.168.13.0
192.168.14.0
192.168.15.0

So, what is the access list? Like this..

conf t
access-list 1 permit 192.168.4.0 0.0.10.0 router rip ver 2 distribute-list
1 in f0/0

Pls advise~~~ Thanks!!

Albert

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_______________________________________
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