Re: Block some IP address from other router

From: Bob Sinclair (bobsinclair@frontiernet.net)
Date: Wed Apr 26 2006 - 09:01:42 GMT-3


Albert,

About this:

access-list 1 permit 192.168.4.0 0.0.3.0
access-list 1 permit 102.168.12.0 0.0.3.0

Here are the bit patterns:

4 0100
5 0101
6 0110
7 0111

12 1100
13 1101
14 1110
15 1111

Laid out as above it can be seen that we need to provide bases of 4 and 12 and
let the last two bits vary.

If mask length is specified:

ip prefix-list 1 permit 192.168.4.0/22 ge 24 le24
ip prefix-list 1 permit 192.168.12.0/22 ge 24 le 34

HTH,

Bob Sinclair
CCIE #10427, CCSI 30427
www.netmasterclass.net

  ----- Original Message -----
  From: Albert Ip
  To: ccielab@groupstudy.com
  Sent: Wednesday, April 26, 2006 5:44 AM
  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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