From: Ben (bmunyao@gmail.com)
Date: Fri Jun 29 2007 - 11:06:06 ART
Naresh,
Mcast forwarding is determined by the existing PIM tree at each router. This
tree is determined by the PIM mode in use, i.e. Spare/dense mode, pruned
branches ......
I don't think there is an equivalent of ARP for multicast, since each source
router/host can work out the corresponding L2 multicast address for an IP
group address without refering to a neighbor. This is what i think, but
perhaps someone else cares to comment.
Ben
On 6/29/07, Naresh Myaka <want2bccie@gmail.com> wrote:
>
> Hi Douglas,
>
> Thanks for the reply,
>
> What u said is perfect, that router will follow basic unicasting for
> 1.1.1.1.
> What if the incoming packet is mutlicast packet.
> Will it still does the L2 lookup before L3 lookup and if it does then when
> it finds Multicast MAC address in incoming packet's as destionation MAC
> addres.
>
> Regards,
> Naresh Myaka
>
>
> On 6/28/07, Douglas M Todd, Jr <dtodd@partners.org> wrote:
> >
> > Hi:
> >
> > R2 needs to do a lookup to know which interface to place the packet on.
> > Thus the lookup happens before the rewrite on the L2 header (mac address
> > as well as L2 technology). At this point it can then RW the L2 header to
> > the correct framing for the interface.
> >
> > 1.1.1.1 is not a multicast address so it will just be unicast and follow
> > the basics for unicast.
> >
> >
> >
> > Naresh Myaka wrote:
> > > Hi GS,
> > >
> > > R1|F0/0------F0/1|R2|F0/0-----F0/0|R3|F0/1|1.1.1.1
> > >
> > > When R1 sends a unicast packets with destination address 1.1.1.1, and
> > when
> > > packet arrives on R2
> > > before doing IP lookup does it checks for destionaton MAC address from
> > > incoming packet.
> > >
> > > If it checks for the dest. MAC add. should it needs to match with MAC
> of
> > > R2's incoming interface address.
> > >
> > > What if it is not match with incoming interface? as in multicast the
> > Dest.
> > > MAC address in incoming packet is Multicast
> > > MAC address.
> > >
> > > Regards,
> > > Naresh Myaka
> > >
> > >
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