Check out the following link for a free subnet mask and wildcard mask calculator from boson. I use it myself.
http://www.boson.com/promo/utilities.htm ""Brett spunt"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Great, detailed explanation ! > > Thanks! > > Brett Michael Spunt > Internetworking Engineer > CCNP,MCSE,CIPT,CCNA,MCP,CNA,A+ > 818 734-6880 ext.59 > [EMAIL PROTECTED] > > > > > > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of > Haakon Claassen (hclaasse) > Sent: Sunday, September 29, 2002 1:28 PM > To: [EMAIL PROTECTED] > Subject: RE: Filter odd routes via wildcard bits - How?? [7:54496] > > > Hi > > Just do the binary calculus > > 0.0.254.255 is 0000 0000. 0000 0000. 1111 1110 . 1111 1111 > > apply that to your prefix 172.168.1.0 > > > the first two bytes (172 and 168) will have to match > and the last bit of the 3rd byte needs to be 1 > > so that would be 172.168.1 .3 .5 .7 .8 > in the other case .0 .2 .4 .6 you have a 0 at that position > > > These maches the routes to be denied (the odd ones) > And the even gets permitted by the permit any > > > > In short > subnet masks need to be contiguous 1 ones followed by contiguous > zeros > wildcards don't 1010 0111 . 1111 0000 . 1110 0111 . 1010 1010 is a > valid wildcard ( 167.240.199.170) > > regs > > > > > Haakon Claassen > EMEA - IT Transport Services -WAN > > Cisco Systems > De Kleetlaan 6b - Pegasus Park > B-1831 Diegem (Belgium) > > > > -----Original Message----- > From: Cisco Nuts [mailto:[EMAIL PROTECTED]] > Sent: zondag 29 september 2002 20:59 > To: [EMAIL PROTECTED] > Subject: Filter odd routes via wildcard bits - How?? [7:54496] > > Hello, > > I am trying to understand how a wildcard mask of 0.0.254.255 filters odd > > routes so that only even routes get across the router. > > Ex. If you have routes for 172.168.1.0/24, 2.0/24, 3.0/24, 4.0/24, > 5.0/24, > 6.0/24 and you have an access-list of: > > #access-list 11 deny 172.168.1.0 0.0.254.255 > #access-list 11 permit any > > And a: > > #distribute-list 11 out > > This will allow only: 172.168.2.0/24, 4.0/24 and 6.0/24 routes out. > > Anyone can kindly explain the magic of this 0.0.254.255 wildcard? > > Thank you. > > Sincerely. > > > BTW: Anyone know the link on this on CCO? > > > > > > > > > _________________________________________________________________ > Send and receive Hotmail on your mobile device: http://mobile.msn.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=54506&t=54496 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
