[nsp] multicast questions

[Spencer Garrett]

On Thu, 6 May 2004, Charles Sprickman wrote:

> Anyone?  It's not like I'm asking about ipv6... :)
> 
> On Mon, 3 May 2004, Charles Sprickman wrote:
> 
> > Hi,
> >
> > I've got a few questions about multicast, mostly Cisco, but there's some
> > other issues that perhaps some of you have dealt with.
> >
> > First issue, does anyone know if RBE (used for bridged DSL circuits coming
> > in on an ATM line) passes multicast?  Meaning, does it look like a LAN to
> > multiple hosts in the same subnet that are all bridged?  From what I can
> > see so far it seems not, but it would be very helpful if someone could
> > confirm that.

No.  RBE interfaces are *routed*, not bridged.  They just have an ethernet
encapsulation as though they were a 1-port bridge.  You can't put multiple
RBE interfaces in the same subnet.

> > The second issue is more generic, and I apologize for bringing this to
> > -nsp, but I have to imagine some of you have done this before.
> >
> > I need to make multicast "work" for a group of 10 DSL lines.  I thought
> > this would be simple; just bridge all of them using RBE and be done with
> > it.  The server is Window Media server on W2K Server.  It seems it will
> > not allow any multicast stations to be defined unless you enable the W2K
> > routing services and setup IGMP.  However, if you do this, the stream is
> > not available on the "local" all-hosts or all-routers IPs; it's off in
> > it's own little range.  So that complicates things.

You can use IRB (integrated routing and bridging), put all of the 
subinterfaces into the same bridge group, and then define a bvi interface 
with the subnet address that you want.  You might be able to use a single
multipoint interface if you enable the "broadcast" option on each pvc, but
this is something I haven't tried.

> > So now I'm at a loss.  The multicast support on DSL CPE routers seems a
> > bit dodgy, and for the most part completely undocumented by the vendor
> > (Netopia and Zyxel are the choices).  And since I don't know what RBE does
> > with multicast, I may need a router at all sites.  Argh.  Any pointers to
> > how to setup the Cisco that terminates all these connections to handle
> > this scenario?
> >
> > I've had little luck finding a good high-traffic multicast list,
> > especially one that will even touch a question that veers into the windows
> > world.
> >
> > Any help at all is appreciated, even a pointer to another good list.
> >
> > Thanks,
> >
> > Charles
> >
> > --
> > Charles Sprickman
> > spork at inch.com
> >
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> >
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