From: ccie2be (ccie2be@nyc.rr.com)
Date: Thu Aug 12 2004 - 18:53:55 GMT-3
Andy,
Thanks for your reply. I appreciate it.
So, just to be 100% clear, you're saying that if sparse mode is being used,
I can have a mcast source behind one f/r spoke router and a mcast receiver
behind a different spoke and the hub will forward mcast traffic out the same
physical interface but with a different dlci from which the mcast came in as
long as ip pim nbma mode is configured on the hub?
But, you're also saying that this same method won't work if dense mode is
being used, right?
Why is that?
And, what about if sparse-dense mode is used?
Thanks, tim
----- Original Message -----
From: "Andy Canizares" <ccie@jzr.com>
To: "'ccie2be'" <ccie2be@nyc.rr.com>; "'Group Study'"
<ccielab@groupstudy.com>
Sent: Thursday, August 12, 2004 5:12 PM
Subject: RE: Multicast split horizon
> For Spare-mode, check out the "ip pim nbma-mode" command. It will listen
to
> the multicast "per pvc" instead of per interface and allow multicast to be
> forwarded between spokes.
>
> -Andy
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> ccie2be
> Sent: Wednesday, August 11, 2004 7:01 PM
> To: Group Study
> Subject: Multicast split horizon
>
>
> Hi guys,
>
> I know that in some scenarios multicast traffic can't be sent out the same
> physical interface from which it came in.
>
> For example, when running sparse mode over a partial mesh f/r network when
> the hub isn't configured with ip pim nbma mode. (See IE lab 4.)
>
>
> hub
> spoke1 --- s 0/0 --- spoke2
>
> If spoke2 is a member of a mcast group and spoke 1 pings that mcast group,
> the ping will fail because of this.
>
> One way around this problem is to create a tunnel from spoke 1 to spoke 2.
>
> Question1: Is this the only way to overcome this multicast split horizon
> problem?
>
> Q2: Is this SPLIT HORIZON PROBLEM ALWAYS present regardless of mode
(dense
> vs
> sparse) and regardless of if hub interface has ip pim nbma mode
configured?
>
> Thanks, Tim
>
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