From: Shine Joseph (shinepjoseph@iprimus.com.au)
Date: Sun Mar 30 2008 - 22:07:16 ART
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
_____
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,
>
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