RE: Multicast Grouping

From: Mike Haddad (mike.haddad@hotmail.com)
Date: Tue Apr 01 2008 - 00:01:59 ART


Hello Joseph,

   Thanks a lot for the examples. I appreciate taking the time for that.
However, for the 44 example you meant 3,4, and 6 right?
Regards,

From: shinepjoseph@iprimus.com.auTo: mike.haddad@hotmail.com;
ccielab@groupstudy.comSubject: RE: Multicast GroupingDate: Mon, 31 Mar 2008
12:07:16 +1100

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 AMTo: Shine Joseph; ccielab@groupstudy.comSubject: 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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