Go CCIE Go!! - A Cisco Certified Internetwork Expert

Mike,

No. you can ahave any value from 0 to 255 for the wild cards. I will give you a couple of examples.

The wild card 12 is valid, but would match only the 3rd and 4th bits from LSB - from right most.
That is, when you write them in binary, it becomes
0000 0000 - 0
0000 0100 - 4
0000 1000 - 8
0000 1100 - 12

So when you use this wild card in an access-list it matches only these 4 addresses.

A wild card of 44 means either 0 or 1 on the bit positions 3, 5, 6 or in binary

0000 0000 - 0
0000 0100 - 4
0000 1000 - 8
0000 1100 - 12
0010 0000 - 32
0010 0100 - 36
0010 1000 - 40
0010 1100 - 44

Thus, the wild card of 44 matches the above 8 addresses.

HTH,
Shine

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From: Mike Haddad [mailto:mike.haddad@hotmail.com] Sent: Monday, 31 March 2008 11:51 AM To: Shine Joseph; ccielab@groupstudy.com Subject: RE: Multicast Grouping

Hello Shine, You’re right and as long as I understand the valid wildcards are : 1 3 7 15 31 63 127 and 255. So using a wild card of 12 is considered invalid? Thanks,
> From: shinepjoseph@iprimus.com.au > To: mike.haddad@hotmail.com; ccielab@groupstudy.com > Subject: RE: Multicast Grouping > Date: Sun, 30 Mar 2008 22:09:38 +1100 > > Mike, > > Write them in binary. > 226 - 1110 0010 > 12 - 0000 1100 > > The possible combinations would be: > 1110 0010 - 226 > 1110 0110 - 230 > 1110 1010 - 234 > 1110 1110 - 238 > > So by having a mask of 12 you are are matching only above 4 addresses. > > HTH, > Shine > > > —–Original Message—– > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Mike > Haddad > Sent: Sunday, 30 March 2008 5:55 PM > To: ccielab@groupstudy.com > Subject: Multicast Grouping > > Hello, > > I still don’t understand why the below ACL can’t be grouped: > interface Loopback0 > ip pim sparse-dense-mode > ! > ip pim send-rp-announce Loopback0 scope 16 group-list 50 > ! > access-list 50 permit 226.0.0.0 1.255.255.255 > access-list 50 permit 228.0.0.0 3.255.255.255 > access-list 50 permit 232.0.0.0 3.255.255.255 > access-list 50 permit 236.0.0.0 1.255.255.255 > access-list 50 permit 238.0.0.0 0.255.255.255 > > > Why can’t we group them as: > access-list 50 permit 226.0.0.0 12.255.255.255 > > Thanks for the clarification, > > _________________________________________________________________ > Enter the Hunt & you could win a 2008 Eclipse Spyder! Click here to enter! > http://g.msn.ca/ca55/213 > > _______________________________________________________________________ > Subscription information may be found at: > http://www.groupstudy.com/list/CCIELab.html > >

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