According to the original post: "Perfect explanation . We want 192.1.1.1 192.1.3.1 192.1.5.1 192.1.7.1 192.1.9.1" So the fourth octet in each is a .1.... With a wildcard mask of .0 in that octet, it's telling the router that all bits in that octet must remain the same as when they started. If we were matching routes, I'd assume it would be a .0 in the starting position, but that's not what the original question was. So keep all bits/octets in your focus when looking at problems like this!
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE-M #153, JNCIS-ER, 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! [EMAIL PROTECTED] Telephone: +1.810.326.1444 Fax: +1.810.454.0130 http://www.ipexpert.com _____ From: GAURAV MADAN [mailto:[EMAIL PROTECTED] Sent: Saturday, January 26, 2008 2:19 PM To: [EMAIL PROTECTED] Cc: Ralph Olsen; [email protected] Subject: Re: [OSL | CCIE_RS] Wildcard Q But in last octet we always want value of 1 .. isnt it ? so i guess it would not be wrong to write 192.1.1.1 .. do correct me if i miss something .. 192.1.1.1 0.0.14.0 will include 192.1.1.1 , 192.1.3.1 , 192.1.5.1 , 192.1.7.1 , 192.1.9.1 Gaurav Madan. On 1/27/08, Scott Morris <[EMAIL PROTECTED]> wrote: Because 192.1.1.0 <http://192.1.1.0/> would set your initial starting bits. Once you put your "starting point" in place and then apply a mask (which tells you which bits can change and which ones cannot) then the results you get will be different! HTH, Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE-M #153, JNCIS-ER, 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! [EMAIL PROTECTED] Telephone: +1.810.326.1444 Fax: +1.810.454.0130 http://www.ipexpert.com <http://www.ipexpert.com/> _____ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of GAURAV MADAN Sent: Saturday, January 26, 2008 12:39 PM To: Ralph Olsen Cc: [email protected] Subject: Re: [OSL | CCIE_RS] Wildcard Q Hi Perfect explanation . We want 192.1.1.1 <http://192.1.1.1/> 192.1.3.1 <http://192.1.3.1/> 192.1.5.1 <http://192.1.5.1/> 192.1.7.1 <http://192.1.7.1/> 192.1.9.1 <http://192.1.9.1/> This will make 192.1.1.1 <http://192.1.1.1/> 0.0.14.0 <http://0.0.14.0/> . Which is why we write access-list 1 permit 192.1.1.1 <http://192.1.1.1/> 0.0.14.0 <http://0.0.14.0/> Can any one comment on why they have written 192.1.1.0 <http://192.1.1.0/> 0.0.14.0 <http://0.0.14.0/> instead of 192.1.1.1 <http://192.1.1.1/> 0.0.14.0 <http://0.0.14.0/> Gaurav Madan. On 1/26/08, Ralph Olsen <[EMAIL PROTECTED]> wrote: Hi Khalid, You don't care about the 1st, 2nd and 4th octet, because that will be 0 as it doesn't change. You will have the 3rd octet being 1 3 5 7 9 If you write that in binary you will get 1 00000001 3 00000011 5 00000101 7 00000111 9 00001001 So in the wildcard mask we know that a fixed bit will be marked as a 0 and a wildcard bit will be marked as a 1. 1 00000001 3 00000011 5 00000101 7 00000111 9 00001001 00001110 <-- Bit 5,6,7 (from left to right) is wildcard bits. And converting 00001110 to decimal will give you 14. The wildcard mask being 0.0.14.0 <http://0.0.14.0/> . Hint: Use Windows notepad and calculator and write all IP address' in binary. That will give you a better visual overview. /Ralph Olsen > Hi all, > > we have 2 routers R1.......> R2 and R1 has 10 Lo interfaces: > Lo1: 192.1.1.1/24 <http://192.1.1.1/24> > Lo2: 192.1.2.1/24 <http://192.1.2.1/24> > Lo3L 192.1.3.1/24 <http://192.1.3.1/24> upto 192.1.10.1/24 > <http://192.1.10.1/24> > > we need to configure R2 to ONLY receive the odd addresses from R1 > > the answer was: > > R2: > access-list 1 permit 192.1.1.0 <http://192.1.1.0/> <http://192.1.1.0 <http://192.1.1.0/> > 0.0.14.0 <http://0.0.14.0/> > <http://0.0.14.0 <http://0.0.14.0/> > > router rip > distance 255 150.50.17.1 <http://150.50.17.1/> <http://150.50.17.1 <http://150.50.17.1/> > 255.255.255.255 <http://255.255.255.255/> > <http://255.255.255.255 <http://255.255.255.255/> > 1 > Note: 150.50.17.1 <http://150.50.17.1/> <http://150.50.17.1 <http://150.50.17.1/> > is R1 > this Q is from the workbook. Can you give me a full explanation > about 0.0.14.0 <http://0.0.14.0/> <http://0.0.14.0 <http://0.0.14.0/> > > > thnx
