From: ccie2be (ccie2be@nyc.rr.com)
Date: Mon Nov 08 2004 - 00:47:57 GMT-3
Are you sure there is a command, ip multicast access-group. I looked for it
but came up empty, however, there is a command, ip igmp access-group which
is used to prevent joins.
Now, this might be obvious to lots of people, but I didn't notice this until
it was explicitly pointed out to me, I think by Scott Morris.
When the ip multicast boundary # command is used, it's referencing an acl
just like the command, ip access-group #, so I wondered why was the ip
multcast boundary command needed. Isn't the ip access-group sufficient to
do the job?
The answer, of course, is it isn't. This is because when the ip
access-group # command is used, it interprets the ip addresses in the acl as
source ip addresses. With the command, ip multicast boundary #, the ip
addresses referenced by the acl are interpreted as destination addresses.
A minor point, no doubt, but it highlights how important it is to pay
attention to details.
HTH, Tim
----- Original Message -----
From: "Hai Minh" <minh@ipmac.com.vn>
To: <ccielab@groupstudy.com>
Sent: Saturday, November 06, 2004 11:35 PM
Subject: Multicast question
> Hi group,
>
> I have this configuration. What is the different between the command "ip
> multicast boundary" and "ip multicast access-group" in this case ? I think
> both of them are used to block the hosts to join to the multicast group
> 226.26.26.26.
>
> Could someone please explain to me ?
>
> Thanks in advance
>
> ================
> R1
> interface E0/0
> ip multicast boundary 1
>
> interface E0/1
> ip multicast access-group 1
>
> access-list 1 deny 226.26.26.26
> access-list 1 permit any
> =======================
>
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